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I

74-19,887
VAIL, Harry David, III, 1943SPIDERS ASSOCIATED WITH DWELLINGS IN MICHIGAN
WTIH SPECIAL BflHASIS ON THE PREDATORY
BEHAVIOR OF CHIRICANIHIUM INCLUSUM HENTZ
CARANEAE:CLUBIUNU3AKJ.----------Michigan State University, Ph.D., 1974
Zoology

University Microfilms, A XEROXCom pany, A nn Arbor, Michigan

SPIDERS ASSOCIATED WITH DWELLINGS IN MICHIGAN
WITH SPECIAL EMPHASIS ON THE PREDATORY
BEHAVIOR OF CHIRICANTHIUM INCLUSUM
HENTZ

(ARANEAE:CLUBIONIDAE)
By

Harry David Vail III

A DISSERTATION
Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of
DOCTOR OF PHILOSOPHY
Department of Zoology
1974

ABSTRACT
SPIDERS ASSOCIATED WITH DWELLINGS IN MICHIGAN
WITH SPECIAL EMPHASIS ON THE PREDATORY
BEHAVIOR OF CHIRICANTHIUM INCLUSUM
HENTZ (ARANEAE:C L U B I ONIDAE)
By
Harry David Vail III

Of the more than 371 species of spiders reported
from M i c h i g a n , 106

<28.5%) were captured from dwellings.

Twelve species were found to represent 51.5% of the 1147
specimens captured.

These species were from six families,

three w e b spinners and three non-web spinners.

Analysis

indicated that the spider numbers fluctuated during a cal­
endar year to produce two distinct peaks.

One peak was

generally larger and termed the major peak, with the smaller
peak termed the minor peak.
The two peaks were observed during the spring and
fall with a period of decreasing numbers of animals d u r ­
ing the summer and winter.

The majority of the 12 spe­

cies exhibited spring major peaks and fall minor peaks
with reduced numbers during the summer months.

Examina­

tion of the individual species indicated that the mature
females and immature forms were dominant during the major­
ity of the year.

Mature males were in low numbers during

Harry David Vail III
the spring and summer and disappeared completely during
the fall, winter and early spring months.
Spider bites confirmed during the study occurred
during those periods when both the spiders and humans were
about in greatest numbers.

Though considered as serious

by the individual, the bites were diagnosed as not seri­
ous by medical doctors, producing slight local swelling
and an itching sensation which persisted for only a few
days.
The survey of buildings at the local level revealed
that the most common species were the same as those found
during the state wide survey.

Seven species accounted

for more than 60% of the 3346 specimens captured.

These

seven species were from four families representing two w e b
*• *■

spinners and two non-web s p i n n e r s .

The same peak phenomena

were observed in all three building types and the same re­
lationships between males,

females and immatures.

There appeared to be no affect exerted by the build­
ing type on the species composition, but an effect was
noticed on the relative densities of the individual species.
The three weather parameters measured indicated that
the outside temperature exerted a force on the spiders
causing an increase in numbers found indoors.

The inside

temperature and the relative humidity allowed the animals
to survive once the move was made.

Harry David Vail III
The predation studies on Chiricanthium inclusum
Hentz indicated that short contact distances coupled with
random search patterns necessitated traveling in excess
of one half mile by mature male specimens.

Mature females

and immature forms traveled proportionally less.

These

nocturnal animals were found to use and re-use resting
cells depending on the prey density and the distances
traveled from the previously constructed cell when the
light levels suppassed 10 to 12 foot candles.

The prey

preferred by these animals were soft bodied with a high
moisture content and low mobility.
Prey sizes selected by the animals could be altered
by the hunger state of the animals and the sizes of the
prospective prey.
flexible.

The numbers of prey eaten was not as

When the animals were satiated, the number of

prey present had no effect on the number killed.

Animals

that were hunger stressed would eat until apparently
satiated and then would not attack and kill further.

In­

creases in prey densities served to reduce the time to
initial capture as did the increase in the numbers of
predators.

These spiders did not exhibit cannabalism

in the test chambers or in the rearing chambers as long
as the food levels were maintained at levels above starvai

tion.

There was a distinct avoidance reaction by the

animals towards one another even when the densities were
quite high.

ACKNOWLEDGMENTS

My thanks go to Dr. T. Wayne Porter, who, while
serving as my major professor, helped instill in me his
interest in Invertebrate Zoology, and to Dr. J. Alan
Holman for the financial support provided while working
as a research assistant under his direction at the Michi­
gan State University Museum.
My deep appreciation goes to Dr. Richard J. Sauer
for his time and efforts expended in my behalf.

His un­

selfish expenditure of both scientific resources and
moral support helped make this project enjoyable and re­
warding.

Our discussions, both scientific and non-

scientific', were of great value during my time spent as
a student of "spiders."
Especial thanks go to Dr. Dean L. Haynes.

His in­

sight into biological problems and his philosophy regard­
ing scientific excellence will always be remembered.

His

sharing of both valuable time and resources helped make
this study complete.
Finally,

I w o u l d like to thank m y wife Dana.

With

out her patience and understanding during this period,
the thesis project and educational background needed for
professional excellence would not have been reached.

ii

TABLE OF CONTENTS
Page
LIST OF

T A B L E S .....................................

V

LIST OF

F I G U R E S .....................................

vi

LIST OF

P L A T E S ........................................ viii

INTRODUCTION .........................................

1

MATERIALS AND METHODS

...............................

4

State-wide Study
...........................
Local Quantitative Study .....................
Predatory Behavior of Chiricanthium
inclusum Hentz
...........................
Predator
..................................
Rearing ......................................
P r e y .........................................
Rearing the P r e y ...........................
A p p a r a t u s ..................................
Experimental Design
........................

4
6
7
7
8
10
13
14
17

R E S U L T S .............................................

25

State-wide Survey
...........................
25
Local Quantitative Study .....................
43
Wooden Building ...............................
55
Brick B u i l d i n g s ...............................
66
Predatory Behavior ...........................
77
Prey Contact Distance
.....................
77
Effects of Light on Hunting Behavior
.
.
77
.....................
81
Prey Moisture Content
Search Patterns
...........................
85
Resting Cell S t u d y ........................
89
Effects of Prey Size
. . . . . . . .
97
Distances Traveled Study .....................
101
Prey Density S t u d y ............................... 105
D I S C U S S I O N ............................................. Ill

Page
A P P E N D I C E S ............................................. 129
LIST OP R E F E R E N C E S .......................................138

iv

LIST OF TABLES
Table
1.
2.
3.

Page
Taxonomic Listing of Spiders Received from
the State-wide Survey ........................

26

Twelve Most Frequently Received Species
from State-wide Survey
.....................

36

Number of Individuals Per Sex in the Top
Twelve Species
...............................

40

4.

Taxonomic Listing Local Spider Survey

5.

Sex Breakdown for Five Species Most Fre­
quently Captured in Metal Buildings
. . .

52

Numbers of Spiders per 100 Square Feet in
Two Metal B u i l d i n g s ........................

56

Sex Breakdown for Seven Species Most Fre­
quently Captured in Wooden Building
. . .

63

Numbers of Spiders per 100 Square Feet in
Wooden Building ...............................

65

Sex Breakdown for Five Most Frequently C a p ­
tured Species in Brick Buildings
. . . .

74

Numbers of Spiders per 100 Square Feet in
10 Brick B u i l d i n g s ............................

75

6.
7.
8.
9.
10.
11.

.

.

45

Time to Initial Capture for Predators in
Different Densities and Prey in Different
D e n s i t i e s .......................................... 107

v

LIST OF FIGURES
Figure
1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

Page
Map of Michigan showing counties in which
agents participated in state-wide survey
and number of specimens received from
each c o u n t y ...................................

30

Mean monthly temperatures compared with
percentages of spiders sent in by county
a g e n t s ......................................

32

Numbers of spiders broken down by sex and
maturity level by the month for state­
wide s u r v e y ...................................

37

Temperatures both inside and outside metal
buildings with relative humidity inside
buildings compared with monthly changes in
spider numbers captures .....................

47

Proportional breakdown by sex and maturity
level of most frequently each of the top
twelve species................................

50

Temperatures both inside and outside wooden
building and relative humidity inside
building compared with monthly changes in
spider numbers captures .....................

58

Proportional breakdown by sex and maturity
level of seven most frequently captured
species in wooden building .................

60

Temperatures inside and outside brick
buildings and relative humidity inside
buildings compared with monthly changes
in spider numbers captured .................

67

Percentages of total numbers of spiders
collected from five most numerous species
from brick b u i l d i n g s ........................

70

Numbers of spiders remaining active before
and after starvation observed at different
foot candle l e v e l s ........................

79

vi

Figure
11.

12.

13.

14.

15.
16.
17.

Page
Three graphs showing numbers of individual
dying for each of three hunger stress
p e r i o d s ......................................

82

Graph showing deviation from mean value of
20 turns during random search pattern in­
vestigation ...................................

87

Part 1 : Original number of resting cells
found with increase over two week period
Part 2: Changes in resting cell occupancy
and new cell construction rate
. . . .

90

Three graphs showing number of spiders
returning to resting cells in different
sized search areas
. . . . . . . .

93

Percent attack rates for three classes of
spiders under three hunger stress regimes

.

98

Distances traveled by three classes of
spiders under six hunger stree regimes

.

102

.

The three predator densities over avail­
able searching area at different prey
d e n s i t i e s ...................................... 108

vii

LIST OF PLATES
Page

Plate
1 . Circular track used to determine distances
traveled by experimental spiders
. . . .

viii

15

INTRODUCTION

Spiders, since time immemorial, have held a spe­
cial place in man's mind as an animal to be feared and/or
destroyed.

Evidence for these beliefs are legend.

For

example, a Mediterranean dance called the Tarantela was
thought to offset the effects of the bite of an aggressive
lycosid spider native to the region, but for which the
tarantula has been named and blamed.

Another example is

the small black spider the Indians of California called
"The one with long black fingers that causes sickness,"
more commonly known as the Black Widow.
childrens nursery rhyme,

Or perhaps the

"Little Miss Muffet," which can

be traced to a 19th century incident recorded by an English
physician and father regarding an incident involving his
daughter.
Most of the existing information about the occurance of spiders within dwellings is generally found scat­
tered in the locality portions of species descriptions.
Bits of such information can be found in Kaston

(1948),

Levi

(1955,1957,1959,1962,1963,1966,1968,1972), Chamber-

lain

(1933), Dondale

others.

(1961), Gertsch

(1949) and countless

There has been little or no work done to ascribe

1

2
particular species of spiders to particular types of dwe l ­
lings at particular times of the year.

Spiders discovered

within structures are generally destroyed and/or removed
with little regard to the place they hold in the ecologi­
cal community.
Predatory behavior,

as described by Hoiling

(1959),

has been applied to a variety of invertebrate predators,
including spiders in particular, by Turnbull
Haynes

(1966), Loughton, Derry and W e s t

ska-Prot

(1966,1968,1970).

(1960,1964),

(1963)

and Dabrow-

Studies involving spider p r e d a ­

tion as a portion of a larger study were conducted by
Eberhard

(1967), Gardner

(1965), Levi

(1968), Lovell

Moulder et a l . (1970) and Peck and Whitcomb

(1970).

(1915),
The

majority of these studies w e r e observations of spiders
that constructed a capture w e b and w a i t e d for prey to
come to them or spiders that are visually stimulated and
hunt with both eyesight and agility.
The aspect of foraging that considered either
traveling of the spider or moving of the w e b has been in ­
vestigated in the Lycosidae by Turnbull
lander

(1967).

Turnbull

(1966)

and H o l ­

(1964) described the movements

of the web location of Achaeranea tepidariorum

(Koch)

in

response to varying prey densities.
A project was proposed to assess associations of
spider within human dwellings, w i t h the aim of developing

3
an understanding of the niches spiders have in the animal
world as part of the biological community and as sources
of biological control of insect pests of man.
The study was divided in three main parts:
to determine, on a state-wide level,

first,

the species of spiders

that are found within dwellings during the year?

second,

to determine on a local level the quantitative aspects of
both resident and migratory spider populations through
the year as related to building type and season of the
year; and third, to characterize the predatory behavior
of one particular species

(Chiricanthium inclusum Hentz)

and determine its effects on the resident prey population.

MATERIALS AND METHODS
State-wide Study
The extensive portion of the study was to sample
Michigan as efficiently as possible without expending unnecessary time and effort traveling.

A method of collect­

ing was proposed in which the County Extension Agents
throughout the state were asked to participate.

In Febru­

ary, 1972, a letter outlining the proposed project was
drafted and sent to the 83 County Agents.

Included in the

letter was a sample of the data sheet to be completed for
each specimen collected and a two dram, neoprene stoppered
glass vial which contained 70% ethyl alcohol and a number
to designate the county and the s p e c i m e n .

Return of an

enclosed addressed card with the introductory letter ack­
nowledged willingness of the agent to participate.
83 county agents contacted,
53 sent in specimens.

Of the

67 agreed to participate and

Immediately upon receipt of the

card, a set of 12 vials and data sheets,

correspondingly

numbered,

were forwarded to the agent.

As each set of

vials was

returned,

set of 12

ascending numbers and data sheets.

another was forwarded with the next

Data requested included date of collection, type
and location of the dwelling from which the spider was

5
taken/ actual location within the dwelling, if the spider
was found in or near a web and if a bite could be associa­
ted with the specimen.

A sample of the letter and the

data sheet is provided in Appendix A.
As soon as spiders began arriving,

they were iden­

tified to species and data were assembled on the numbers
and species of spiders collected from each county.

Then

a phylogenetic listing was made with numbers of individuals
in each species and sex, including the number of immatures.
The data was divided into monthly totals to determine the
effects of seasonal changes on the populations present as
well as the influence of the building type on the species
collected.
At the completion of the sampling period, the data
for the 12 species received most often were analyzed for
the months in which they were collected, sex ratios pres­
ent and building types in which they were most frequently
found.

The results of this listing will be provided for

the County Agents in the form of an Extension Bulletin
that will be useful in determining the spider fauna in
dwellings.
One of the objectives of the study was to monitor
the incidence of spider bites that could be traced defin­
itely to a given species.

The procedure was for the indi­

vidual to submit the spider to a Michigan State University

6
Extension office and have a medical doctor examine the
bite.

The doctor would provide a written description of

the symptoms,

reactions and prescribed treatments admin­

istered to the patient.

Of the vast potential for arthropod

bites throughout the summer months, very few were actually
attributed to spiders.
Local Quantitative Study
During January,

1972, several attempts were made

to contact both city and county agencies in order to estab­
lish a regular sampling program in buildings owned and
managed by them.

When this failed, the housing authority

for the University was contacted and permission obtained
to use buildings owned by the University, provided collect­
ing activities did not interfere with their operation.
Thirteen buildings were selected from around the campus
for a one year study.
Beginning in February,

1972, a sampling project

was initiated to determine what effects collecting and re­
moval of spiders on a bi-weekly basis would have on the
resident populations for a period of one month.

Three

samples were taken during the month long period and the
results were examined using a Chi-Square test.

The test

showed that sampling with removal did not significantly
alter the resident populations when done at intervals of
two weeks or longer.

Thus a regular biweekly sampling pro­

gram was started in March,

1972, and ended in March,

1973.

7
The data sheets used were modified from the origi­
nal, with the following additional data being recorded:
temperatures inside and outside the buildings and rela­
tive humidity inside, all taken with an Atkins Thermistor
Psychrometer, Model 3Z02B.

Specimens were collected,

num­

bered in accordance with data s h e e t s , then brought to the
laboratory for identification.

The specimens of C. inclusum

collected were kept alive in rearing vials
Rearing Section)

(See Predator

for future experimentation.

specimens were killed,

The other

placed in numbered vials and stored

for identification at a future date.
From the data collected, monthly changes in spider
populations were noted as well as changes in the measured
weather parameters,

in an attempt to relate weather changes

with noticeable changes in the spider p o p u l a t i o n s .

Through­

out the study, particular attention was placed on C.
i nclusum.
Predatory Behavior of Chiricanthium
inclusum Hentz
Predator
Chiricanthium inclusum was first described by
Hentz in 1875.
and Whitcomb

The general biology was discussed by Peck

(1970).

Included in their study were d e s ­

criptions of the life cycle, mating behavior, mean stadium
for each instar, general food preferences and the effects

8
of several environmental parameters on development and gen­
eral biology.
Rearing
Beginning in the fall of 1971,

specimens of C.

inclusum were collected from buildings on campus and re­
turned alive to the laboratory.

Each animal was placed

in a 20 dram shell vial stoppered with non-absorbent cotton.
Various types of food were offered and after several fa­
miliarization periods by the spiders, one was selected,
based on acceptance by the spiders and the ease in which
the prey could be maintained in the laboratory.

Since

the spiders were collected in buildings having relatively
stable temperatures,

they were maintained in the labora­

tory at room temperature during the winter and spring.
As the outdoor temperature increased during the spring
and summer, accompanied with a marked rise in the relative
humidity,

the animals were moved to a controlled tempera­

ture room where the temperature was maintained within a
range of 70-75 degrees F.

Additional specimens were col­

lected and kept both as experimental animals and as sources
of egg supply to raise future experimental animals.
Initially,

several methods were tried to keep the

moisture levels sufficient to maintain the animals.
Though

Peck

and Whitcomb

(1970)

stated that the normal

ranges of relative humidity have no effect on the animals'

9
health, observations tended to indicate that the animals
began to lose their ability as hunters when the tempera­
ture and relative humidity increased more than 20 units
above that to w h i c h they were accustomed.

In a pilot study

to determine the amount of humidity change needed to alter
the hunting behavior of the spider, it was noted that w h e n
the humidity was raised over 20 percent above that to
which the animals were accustomed, the distances traveled
decreased by as much as 20 percent and the number of prey
animals eaten decreased by up to 33 percent.
M o ist pieces of paper were placed in the rearing
vials, but they dried out rapidly and needed continuous
attention.

Absorbent cotton was tried, but the residues

from the spider meals as well as the fecal materials re­
mained m o i st in the small chambers and resulted in mold
and contamination.

A method reported by Peck

(1970) was

tried using a tube with both ends removed and stoppered
with cotton for easier cleaning.

These tubes were stored

in a horizontal manner and required a considerable amount
of laboratory space.

This method was rejected owing to

the lack of storage space.
burrow

between

and escape.

Also, C. inclusum was able to

the cotton and the glass container side

Therefore, only one open end was considered

an advantage in reducing the numbers of spiders escaping.
Feeding regimens for maintaining the animals were
established at three to five m e d i u m sized Tribolium confusum

10
larvae per day.

This number was determined by feeding the

adult spiders an arbitrary amount, waiting for 24 hours,
counting the number of uneaten larvae, halving this number
and subtracting it from the original number and giving
this amount to the spiders the next meal.

When the spiders

ate those placed in the chambers without leaving one or
two animals uneaten or unattacked,
as the daily ration.

this number was given

The tendency of C. inclusum was not

to attack every prey animal placed in the container,

and

therefore several might be found in the bottom of the con­
tainer depending on the hunger levels of the particular
spider.
Prey
Several types of prey organisms were tried as a
source of food and, after some experimentation,
was determined as the best one to be used.
Peck and Whitcomb

T. confusurn

According to

(1970), the more varied the diet, the

better the animals grew and matured.

According to their

results, a wide variety of animals were introduced to the
spiders and after 24 hours the results of their eating or
rejecting the prey was compared with the acceptance of
Drosophila melanogaster as a test food.
dale

(personel communication)

According to Don-

spiders need a period of

several days to become accustomed to a newly introduced
prey species.

Therefore,

the testing of prey species was

11
conducted for two weeks in order that one be chosen that
was easy to rear in the laboratory, was preferred by the
spiders and was of such a form that similar types could
be expected to be found within dwellings.
The types of prey tested were adult fruit flies,
D. m e l a n o g a s t e r y Ants, F o r m i c i d a e ; Milkweed bugs, Oncopeltus
fasciatus; Cockroaches, Blatta sp. and Periplaneta sp.;
the yellow mealworm,
flour beetle,

Tenebrio m o l i t o r ; and the confused

Tribolium c o n f u s u m .

The fruit fly varieties tried were both winged and
wingless.

Their mobility did not permit the spiders to

capture them and so as a potential experimental prey were
rejected.
Ants were noticed in all the buildings investigated
as well as the Natural Science Building.

When the ants

were placed in a rearing chamber as food for C. i n c l u s u m ,
the spider became very agitated, and if the number of ants
exceeded three or four, they often killed the spider.

There

was never a time when the spiders were observed eating ants.
Several times during the rearing of egg m a s s e s , the ants
got into the rearing chambers and carried off eggs or young
s p iderlings.
Milkweed bugs were tried because of their ease in
rearing, but the spiders would not eat either the adults
or the smaller nymphs.

The rejection of Milkweed bugs

12
could be based on several factors:

a hard exoskeleton,

a possible taste or odor objection,

or perhaps the size

of the more mature specimens.
One of the few animals observed in the dark were
cockroaches.

Several species,

including the adults and

nymphs were tried with the same results as with the M i l k ­
weed bugs.

The hard carapace and the speed and agility

seemed to deter the spiders in their attack.
Mealworms, ranging in size from five to twenty
millimeters, were used with varying degrees of success.
The adult male spiders were able to kill and eat most of
the medium and all of the smaller specimens, but the
thick integument and active thrashing of the prey would
often deter even the most persistent spider.

Smaller

adults and immature spiders often were dislodged and w o u l d
give up the attack.
Flour beetles were tried with the highest degree
of success.

The adult beetles were not readily accepted

due to the hard carapace.

The preferred forms were the

larvae which were attacked and eaten by all sexes and
stages of spiders.

Because of the soft bodies of the

larvae, there were few parts left when the spider had
finished eating.
weight.

The larvae averaged 63-75% moisture by

When these animals were the only food sources,

they were divided into three size classes by inspection:

13
small, less than four mm.; medium,
large, greater than eight mm.

four to eight mm.;

The soft bodies,

apparent

high moisture content and lack of mobility proved them
to be good food sources.
Rearing the Prey
Several one quart jars filled with enriched white
flour were inoculated with 25-30 adult beetles and left
to reproduce at room temperature.

As one culture was

maturing, another was begun with adults from the previous
culture.

To obtain food for the spiders,

a portion of

the flour was poured onto a wire screen of 60 meshes per
inch and the flour sifted.

The larvae were sorted, the

appropriate size removed for food and the rest returned
to the stock culture.
effects of crowding,

When the cultures began to indicate
cannabalism, reduced number of larvae,

and many beetles along the side of the jar, the culture
was discarded and another begun.
Peck and Whitcomb

(1970)

in their experiments with

food preferences, gave the spiders a wide variety of prey
organisms from several Phyla and Classes of animals.

The

preferred organisms were the soft bodied forms, particu­
larly larval forms.
of this study.

Their data agrees with the results

14
Apparatus
Rearing Chambers.--The rearing chambers were 20
dram glass shell vials, stoppered with non-absorbent
cotton and stored vertically in racks.
Experimental Chamb e r s .— Two types of experimental
chambers were used, one for measuring foraging, distances
traveled and the other for observing hunting behavior.

cage °^~
Glass

A.

The chamber used to measure foraging distances
was a clear plexiglass circular track 48 in­
ches in diameter (Plate 1).

B.

The chambers for observing hunting behavior
were three glass aquaria aind a screened cage.

Length
8.5 in.

Width
5.5 in.

Glass

14

in.

Glass

20

in. 10.0 in

Screen
cage

6.6 ft.

8.0 in.

6.6 ft.

Height
6.5 in.
10.0 in.
12.0 in.
6.0 ft.

Surface area

Ratio

292 square in.
2.02 square ft.

1

664 square in.
4.61 square ft.

2

1120 square in.
7.8 square f t .

4

31,104 square in.
216 square ft.

32

15

Plate 1.— Circular track used to determine distances
traveled by experimental spiders.

16

17
L i g h t i n g .— The rearing chambers were placed in a
constant temperature room at 70-74 degrees F and maintained
on a 14:10 light cycle
dark)

(14 hours of light and 10 hours of

to approximate the normal daylight cycle occuring

during the spring,

summer and early fall of the year.

fore any experiments were begun,

Be­

all newly captured ani­

mals were placed in the light room for a minimum of 72
hours to acclimate them to the experimental light cycle.
Experimental Design
The predatory behavior of C. inclusum Hentz ex­
hibited several basic behavioral attributes which will be
examined before the actual predator-prey activities are
evaluated.
Peck and Whitcomb

(1970)

stated that C. inclusum

Hentz is a nocturnal predator that does not see well dur­
ing its normal hunting period.
servations,

On the basis of their o b ­

C. inclusum Hentz located its prey by touching

it with the extended front legs while moving in a forward
direction.

To determine what the critical distance is b e ­

tween the predator and prey before the attack,

five males,

five females and five medium sized immatures were selected
and placed one at a time in the five gallon tanks.

Small

larval forms of T. molitor were placed in the tank at var i ­
ous distances from the rearing chambers containing the spi­
ders.

The test was repeated twice for each specimen and

i

18
the results compared for the significant distances needed
to detect prey.

Prey detection, or the detection of any

object in the path of the spider, was considered as an act­
ion not related to searching;

i.e., pausing with the front

legs extended,

tapping the encountered object, an avoid­

ance reaction,

or a direct attack.

To determine the necessary level of light to in­
itiate hunting response,

five individuals of each sex and

five m e d i u m sized immatures, with two replications each,
were placed in a two gallon tank and measurements made of
the available light by use of a Wilson Illumination meter
model 756 with a quartz filter.
their hunting activities,
in foot candles.

When the animals began

the light intensity was recorded

To determine the effects of hunger,

the

same experiment was run again following 72 hours of star­
vation .
Following the results of Peck and Whitcomb
regarding relative humidity,

(1970)

an evaluation of the moisture

content of their food was made to determine if prey m o i s ­
ture content affected the spiders well being.

Fifteen

spiders of each sex and 15 medium sized immatures were
placed in the constant temperature room at approximately
72 degrees F.

The purpose of the test was to determine

the moisture requirements necessary to maintain healthy
spiders in an environment approximating that found in

19
buildings.

Having determined the approximate moisture con­

tent of the prey, a feeding regimen was established so
that five of each type of animal were fed what had been
determined

(See Predator Rearing Section)

every three,

seven and 10 days.

as a normal meal

During that time, no

water was provided to the spiders.

The relative humidity

was maintained at approximately 45% with the test being
run for six weeks.

The numbers of animals dying were an­

alyzed by sex, maturity,

and feeding regimens.

A study was conducted to determine if the search
patterns of the spider were random.

Three spiders of each

sex and three medium sized immatures were placed in the
six by six foot screen cage one at a time and left to
acclimate for 24 hours.

When the individual spiders

emerged after dark to begin their search activities, a
25 watt red light was used to observe and tabulate their
movements.
The spiders were allowed to wander at will and
whenever they turned one way or the other from the direc­
tion they were going, a "1" was tabulated for a left turn
and a ”2" was tabulated for a right turn.

The spiders

were permitted to make 40 turns for each run.
cations were made for each animal.

Three repli­

In order to determine

the effects of locating prey on the search pattern, prey
were positioned in such a manner that the spider came upon

20
the prey in as natural a manner as possible.

After allow­

ing the spider to feed, the experiment was repeated for
40 more turns, with three replications.

The effects of

starvation on the search patterns were determined by starv­
ing the spiders for 48 hours and repeating the above ex­
periments .
The results were tested using the Wald-Walfowitz
Runs Test, outlined in Conover

(1971) and Bradley

The observations consisted of two types,
"a" and "b."
random,
and

The assumptions are

(1968) .

"1" and "2" or

(1) the samples are

(2) they are mutually independent of each other,

(3) they are

continuous.

The null hypothesis pre­

dicts that the process that generates the sequence is ran­
dom.

The alternative hypothesis is that the variables in

the sequence are dependent on other random variables, or
they are distributed differently from each other.

The

test statistic equals the number of runs of like elements,
called "T."

The

"T" value is compared with values in a

table prepared by Swed and Eisenhart

(1943).

For values

of ”a" or "b" greater than 20, the formula is
y 2ab + 1 + x
/2ab(2ab-a-b)
a " a+b
a yj (a+b) ^ (a+b-1)

where x = the quantile values in a standard normal random
variable.

"TH greater than W signifies acceptance of the

null hypothesis.

21
At the outset of the study, an attempt was made
to census the C. inclusum population within a building by
tabulating the number of resting cells found.

This proved

unreliable because the spiders may use the same resting
cell more than once, or may build two in one 2 4 hour pe­
riod.

Therefore, an experiment was devised to test if

spiders returned to one cell or, if not, what caused the
abandoment of the old cell.

Beginning in February,

1972,

the resting cells in the basement and first floor of the
Natural Science Building were tabulated, the spiders col­
lected and the resting cells removed.

The spiders that

were used in the test were either adults or penultimate
instar animals.

They were marked with watercolor paint

and released in the same areas in which they were collected.
After 24 hours, a new census was made of the marked spi­
ders, and the location of the resting cells recorded.

For

the next two weeks, a daily count was made of the marked
spiders and the location of the resting cells.
At the same time as the above experiment was in
progress a series of tests were run in the laboratory to
determine what effect hunting area size had on the return
to the established resting cells.

Five spiders of each

sex and five medium sized immatures were placed individu­
ally in two gallon chambers and observed for five days
under established feeding regimes.

The number that

22
returned to the original cells and those that did not we r e
recorded.

The same procedure was repeated in five gallon

and 10 gallon chambers and the 6' x 6* x 6' screened cages.
A series of similar experiments were conducted on two lev­
els of predator starvation levels,

48 and 72 hours without

food.
Prey size and its effects on hunting success whe n
associated with predator hunger levels was investigated.
Three size classes, designated small, m e d i u m and large,
were selected from the prey animals.

The small and me d i u m

size classes were selected from T. confusum stocks and
the large size class was selected from T. molitor stocks.
The results of this study were analyzed from three aspects:
sex of the spider, hunger levels of the spiders,

and prey

size, using a two way analysis of variance at three hunger
levels as outlined in Sokal and Rohlf

(1969).

Throughout the study the degree of cannabalism in
this species of spider was noted.

Whenever spiders were

mentioned in the literature, a section was always allowed
to cover aspects of one spider feeding on the same or d i f ­
ferent species.

Peck and Whit c o m b

(1970)

stated that the

incidence of cannabalism among C. inclusum was the highest
among the early instars and decreased markedly in the
adult stages.

Their experiments were conducted in small

glass rearing chambers which affected the normal activities

23
of the spiders.

Even the notorious Black Widow is not as

cannabalistic if she is offered a choice of food

(Gertsch

1949).
The next two portions of the study have to do with
the effectiveness of the predator at various prey densities
and the distances traveled under various hunger regimes.
The hunger regimes were satiated, one, two, three,
and five days without food.

four

The individual spiders were

placed in the circular test chamber and observed under the
red 25 watt light for a full hunting period of 10 hours.
The number of complete circuits around the track were tabu­
lated for each animal and the distances calculated.

To

be sure that the wandering was not a desire to escape,
food was introduced at various times on several sample
tests.
The final portion of the study considered the dens­
ity of prey in relation to the success of the spider in
locating food.

This was accomplished by increasing hunt­

ing area size and varying prey densities to approach the
potential prey densities in the natural environment as op­
posed to the laboratory situation.

The prey densities

varied from a high of one prey per 14.6 square inches to
a low of one prey per 180 square feet.

Within each of the

experimental chambers, prey were placed in a random manner
at densities of one, two,

four, eight and 20 animals per

24
search area.

The random placement of prey was determined

by m a rking off the surface area of the chamber into one
inch s q u a r e s , numbering them in a consecutive manner and
locating the squares to hold prey by drawing random num­
bers from a random numbers table.

The animals were

fastened to the side of the chambers with small pieces of
masking tape.
At the same time that the prey density portion of
the study was being conducted, the effects of intraspecific
non-prey organisms on hunting success was determined by
increasing the number of the number of predators from one
to two and then to four within the same area.
of experiments was run for males.
of three replications each.

Each set

There were five sets

The results were analyzed

using a three by three factorial design in examining the
effects of search area size, prey density, predator density
and the inherent interactions.

RESULTS
State-wide Survey
The 114 7 spider specimens taken from inside buldings
throughout the state represent 16 families,
196 species

(Table 1).

65 genera and

Appendix B contains the numerical

code developed for the spiders collected during this study.
Figure 1 illustrates the 53 counties in which the county
agents participated.

The numbers in each county indicate

the total number of specimens collected in that particular
county.

Appendix B lists the specimens received from each

county in alphabetical order with the county code as used
by the Michigan State Extension Service.
Of the 16 families,

nine were web spinners and

seven were non-web spinners.

Web spinning families were

represented by the Theridiidae,

Pholcidae, Araneidae,

Linyphiidae, Scytodidae, Age l e n i d a e , T e t r a g n a t h i d a e ,
Dictynidae and the A m a u r o b i i d a e .

The non-web spinning

families were represented by the Erigonidae,
Gnaphosidae,
Lycosidae.

Pisauridae, Clubionidae,
Drew and Sauer

Salticidae,

Thomisidae and the

(unpublished data) credit M i c h i ­

gan with 23 families of spiders which contain 153 genera
and 371 species.

The state-wide survey represnted 69.5%

of the potential families,

42.4% of the potential genera

25

TABLE 1.— Taxonomic Listing of Spiders Received from the
State-wide S u r v e y .
Theridiidae

Steatoda
n---II
IV

Theridion
Crustulian
Unknown
Achaeranea
Latrodectus
If

Erigonidae

Hypselistes
Erigone
Unknown

Dictynidae
Salticidae

Phidippus
II
Salticus
Sitticus
fl
fl

Pholcidae
Gnaphosidae

Eris
Metaphidippus
Maevia
Habrocestum
Metacyrba
Icius
Unknown
Pholcus
Spermophora
Zelotes
II
Herpyllus
Gnaphosa
fl

Pisauridae

Drassylus
II
Geodrasus
Drassodes
Dolomedes

II

Pisaurina
IV

borealis
triangulosa
altera
grosa
sp.
murarium
stricta
sp.
tepidariorum
mactans
variolus
florens
sp.
sp.
sublata
sp.
audax
regius
scenicus
palustris
floridanus
pubescens
marginatus
sp.
inclemens
pulex
undata
sp.
sp.
phalangoides
meridionalis
subterraneus
hentzi
ecclesiasticus
muscorum
sp.
nigar
depresus
sp.
sp.
tenebrosus
sexpunctatus
mira
sp.

27
TABLE 1.— (continued).
Araneidae

Araneus
II
VI
II

II
It
II
II
II

Argiope

Clubionidae

Neoacona
Coneipeira
Aramella
Gea
Chiricanthium
Castaneira
Clubiona

71------

Trachelas
n------

Thomisidae

Acfroeca
Misumena
Philodromis
n-------II
II
II
II
II
Xysticus
It
It

Coriarachne
Misumenops

cornutus
sericatus
diadematus
marmoreus
cavatica
undata
dlademia
dumetorum

P.
e.
gnxa
sp.
argentata
aurantia
minima
juniperi
displicata
heptagon
inclusum
mildei
sp.
descripta
tnlineata

abbottr
obesa
sp.
ruber
tranquillas
sp.
ornata
yatia
sp.
pernix
rufus
placidus
vulgaris
w ashita
aureolus
praelustris
sp.
elegans
ferox
funestus
lucosta
acquiescens
sp.
sp.
oblongus
speratus
sp.

28
TABLE 1

(continued).

Linyphiidae

Scytodidae
Agelenidae

Tibellus
n---Thanatus
Unknown
Pityohyphantes
n
Lepthy lphan te s
Linyphia
II
Bathyphantes
Drapetisca
Unknown
Scytodes
Tegenana
Agelenopsis
Coras
Circurina
It

Lycosidae

Cybaeus
Wadotes
Lycosa
II
II
II
II
II
II
It

Pardosa
II
II

Trochosa

Tetragnathidae
Amaurobiidae

Pirata
II
Geolycosa
Tetragnatha
Amaurobius
Callioplus

oblongus
maritimus
formicinus
sp.
phrygianus
costatus
nebulosus
marginata
sp.
pallida
sp.
sp.
thoracica
domestica
pennsylvanica
potteri
sp.
medicinalis
juvenalis
sp.
pallida
sp.
sp.
calcaratus
aspersa
av.ida
praetensis
helluo
punctulata
gulosa
carolinensis
frondicola
moesta
sp.
milvina
moesta
distincta
modica
sp.
terricola
sp.
insularis
sp.
missouriensis
laboriosa
bennetti
tibialis
sp.

29
TABLE 1.— (continued).
Non-spiders

Opiliones
Chelodnethida

Phalangiidae

and 28.5% of the potential species recorded in the State
of Michigan.
Many of the parameters outlined in the materials
and methods section regarding habitat type and house type
were very difficult to quantify in this portion of the
study.

Over 94% of the animals returned were from wooden,

single family dwellings located in a suburban or rural
setting.

Thus the other catagories were very poorly rep­

resented and could not be analyzed as effectively.
The weather parameter available for all the coun­
ties with a degree of reliability was temperature.

Figure

2 presents the variation in air temperature during the
study period, with the numbers of specimens received as
a percentage of the total for the state.

For a period of

four months, May through August,

spider numbers were in­

versely related to temperature.

For the remaining eight

months, both curves approximate each other closely.
ing this period as the temperature increased,
numbers of spiders received,
creased,

Dur­

so did the

and as the temperature d e ­

so did the spider numbers.

30

Figure 1

M a p of Michigan showing counties in which agents
participated in state-wide survey and numbers of
specimens received from each county.

32

Figure 2.— Mean monthly temperatures compared with percent­
ages of spiders sent in by county agents.
-------

Air temperature

------

Animals as a percentage of total number

(N).

33

70

60
hie
50

10 e

30

Months

34
The months in which spider numbers were directly
related.to temperature were also the months in which the
most specimens were received.

In May,

175 specimens or

15.25% of the total were collected and in September,
specimens or 18.6% of the total were collected.

212

When the

mean temperature for the state was at a high of 6 8 degrees
F., the number of spiders was at a low value
of the total)

(75 or 6.4%

for this four month period.

In order that the large numbers of spiders col­
lected could be analyzed in a meaningful manner,

the spe­

cies representing more than 50% of the total were analyzed
in detail.

This decision was made on the basis that many

county agents did not collect sufficient numbers of animals
to make a valid analysis either by county total or by
species in each county.
The 12 species selected on the basis of numbers
can be found on Table 2.

Included are the totals for each

species as well as the percentage of the total numbers and
the percentage of the total for the 12 species.

The 12

species listed represent 591 specimens and 51.5% of the
total for this portion of the study.
When the 12 species are considered on an individual
basis,

two main patterns appear.

Figure 3 displays the

species through the sampling period as actual numbers of
specimens received and the makeup by sex and maturity level.

35
The two patterns are the peaks which appear in both AprilMay and September-October.
larger than the other,

There is generally one peak

labeled the major peak.

The second

pattern is that the major peak may occur either during the
spring or during the fall.
On the basis of the above observed patterns, the
12 species were separated into spring major and fall major
species.

The spring major peak species are Tegenaria domes-

tica, Steatoda bore a l i s , Chiricanthium inclusum, Phidippus
a u d a x , and Salticus scenicus.

Thus species having fall

major peaks are Achaeranea tepidariorum, Aranea sericatus ,
Agelenopsis potteri^Trachelas tranquillas, Herpyllus acclesiasticus and Agelenopsis pennsylvanica.
Of the spring major peak species, there was only
one true web spinner, Steatoda b o r e a l i s .
major peak species were examined,

When the fall

there were two, Achaeranea

tepidariorum and Aranea sericatus.
When the percentages of males to females were ex­
amined, there were more females than males and immatures
combined.

The ratios for the individual species

(Table 3)

ranged from a low of 12 males to 10 females for S. scenicus
to a high of two males to 73 females in A. sericatus.
When the sex ratios are compared with the major
peak data, there is no significant differences between sex
ratios from spring peak through fall peak.

Any peak can

36
TABLE 2.— Twelve Most Frequently Received Species From
State-Wide Survey
Species

No.

Tegenaria domestica

108

9.5

18.2

Achaeranea tepidariorum

90

7.9

15.2

Aranea sericatus

73

6.4

12.3

Agelenopsis potteri

53

4.6

8.9

Steatoda borealis

47

4.1

7.9

Chiricanthium inclusum

47

4.1

7.9

Phidippus audax

43

3.7

7.3

Steatoda triangulosa

38

3.5

6.8

Salticus scenicus

29

2.5

4.9

Trachelas tranquillas

25

2.2

4.2

Herpyllus ecclesiasticus

24

2.0

4.0

Agelenopsis pennsylvanica

22

1.9

3.7

TOTAL

591

% of Total

51.5%

% of Top 12

100.0

The number of specimens reported for each of the 12
most numerous species

37

Figure 3.— Numbers of spiders broken down by sex and
maturity level by the month for state-wide
survey.
;Vf = Female
= Male
= Immatures

38
20
Tegenaria domestica
M
N - 108

15
10

If

5

1 »•v«.
«,

&

0

02

Cfi

TT

15

Achaeranea tepidariorum
N-90

10

5

J=L

*eTi

£u

Number of Animals (N)

0

15
Aranea aericatus

10

Nm77

n

5
0

ni in

m

151
Agelenopsis potter i

10

N «5 3

5
0

H

JE B a

n J

a

1

15
10

H

5

Steatoda borealis
N » 47

M

QQ

0 ____ - s i . n .

15
10

5
0

Chiricanthium inclusum
N-47

I

a

J F
1973

(5$
•
I•t
;•
••
••
a.

M A M

J

JZ L JZ L
J A S
1972

O

N

D

39

15

PhIdlppus oudox

10

N * 43

5

JagL

O

15
Steatoda borea11s

10

N ■ 3«

5

Hn f l n

O

Number of Animals

(N)

10

Saltlcus scontens

5

N = 29

0

15

Trachelas tranqutI las

10

N » 25

5
S3

a

l&S

10

n JZL

Herpy11 us occleslasttcus

5

N = 24

O

aun

it

Agelenopsis ponnsyIvan lea
s

r~i
J bbL

J
F
1973

A

mM nJ
1972

r

N=
J

22

A

S

nn
O

N

D

40

TABLE 3.— Number of Individuals Per Sex in the Top Twelve
Species •
Species

Cf

Tegenaria domestica

46
42.5

42
38.9

17
18.9

Imm.

Total

20

18.5

108
18.3%

69
76.5

4
4.5

90
15.2%

2
2.6

74
96.0

1

1.4

77
13.0%

9
17.0

40
75.5

4
7.5

53
8.9%

6

17.0

33
70.0

13.0

47
7.9%

Chiricanthium inclusum

15
32.0

18
38.3

14
29.7

47
7.9%

Phidippus audax

17
39.5

26
60.5

Steatoda triangulosa

7
18.4

22

12

10

41.5

34.5

Achaeranca tepidariorum
Aranea sericatus
Agelenopsis potteri
Steatoda borealis

8

Salticus scenicus
Trachelas tranguillas

6

24.0
Herpyllus ecclesiasticus
Agelenopsis pennsylvanica

Totals %

9

58.0

0
0

43
7.3%

9
23.6

38
6.4%

7
24.0

29
4.9%

19
76.0

0
0

25
4.2%

10

12

2

41.7

50.0

8.3

24
4.1%

7
31.8

7
31.8

8

22

36.4

372
156
62.9
26.4

3.7%

75
12.1

591

The b o t t o m row of figures associated w i t h each spe­
cies represents percentages of males, females and immatures
of each species total.

41
be examined and the major peak, whether spring or fall,
will consist primarily of females.

Only S. triangulosa

and A. pennsylvanica are represented by having immatures
as the dominant group.
In examining the most frequently occurring species
the top nine are found within dwellings through more than
10 months of the year.

These species over winter either

as penultimate instars or as mature females.
Spider bite data was collected in conjunction with
the State-wide study and produced a total of 18 suspected
bites.

The frequency of bites was plotted over the year

long survey and the bites occurred at two peak periods dur­
ing the year.

The first peak occurred during May which is

the month when the spider population is the highest,
accounted for eight bites.

and

August, the second peak of the

year for the spider populations, was also the second peak
in number of six bites reported.
These two periods coincide with several factors im­
portant to man.

First,

spiders are at their peak densities

during these two months and secondly, people are out and
active during these months, placing themselves in close
contact with potential pests.
Of the 18 suspected bites, only four were confirmed
by capturing the animals during the biting and having a m e d i ­
cal doctor confirm the bite and describe the symptoms and

42
treatments.

Of the four, two were C. inclusum, another was

a pisaurid and the third was an unknown species not collected
or seen by me but which accounted for possible complications
leading to the death of a senior citizen.
Of the two C. inclusum bites, one was on the naval
of a woman and caused an itching sensation and a small red
weal which persisted for several days.

The treatment pre­

scribed was penicillin and a bee sting antivenom.

The sec­

ond bite was on the finger of a woman sleeping in bed, who
awoke following a sharp stinging sensation.

The same sym-

toms were reported and similar treatment prescribed.

The

symptoms described for bites coincide with the data reported
by Furnam and Reeves

(1957) .

Their data comes from one sus­

pected bite reported in the California Medical Journal from
a study done on spider bite venom.
The third confirmed bite was made by a mature female
Dolomedes tenebrosus, of the family Pisauridae.

The bite

was on the buttock of a woman and caused a red weal and
severe itching which persisted for several days.
treatment with penicillin,

Following

the itching and the weal sub-

suded, with no side effects.
The final confirmed bite was reported by a young­
ster who saw the spider bite his grandfather.

The spider

bit the man while he was working on a woodpile near a
stream.

The spider was killed and the man taken to a local

43
hospital.

The man had a history of heart trouble and was

in his mid-seventies, so the death cannot be attributed
directly to the spider bite, but the v e n o m may have caused
complications.

From the description given by the grandson

and the nearness to water, there is reason to suspect that
the spider was a member of the family Pisauridae,

though

it could have been from the family Lycosidae as both families
contain large dark spider species.
Local Quantitative Study
The sampling at the local level produced 3346 spider
specimens representing 12 Families,

32 Genera and 57 Species.

Appendix B provides the numerical code used for both the
state-wide and local studies.

Each building type will be

presented separately with the appropriate weather parameters.
Table 4 contains the species found in the local sur­
vey, representing 625 specimens from 12 families,

32 genera

and 56 species or 18% of the total for the study.

The ani­

mals were taken from two metal quanset-hut structures con­
taining 1950 square feet of surface area each or 3900 square
feet total.

This gives 0.127 animals per square foot per

year or 0.0635 animals per square foot per year per building.
There were six web spinning families and six non-web spin­
ning families.

The web spinning families were the Theridii-

dae, Pholcidae, Araneidae, Dictynidae, Linyphiidae and
Agelenidae.

Non-web spinning families were represented by

44
the Erigonidae, Salticidae, Gnaphosidae,

Thomosidae, Clubi-

onidae and the Lycosidae.
Weather parameters, Figure 4, are shown with the
percentage of spiders collected each month.

The outside

temperature does not follow the inside temperature closely,
but there are similar trends observable between the two.
The outside temperatures ranged from a low of 26 degrees
F in December to a high of 82 degrees F in August, while
the temperature inside the building ranged from a low of
67 degrees F in March to a high of 80 degrees F in August.
Relative humidity ranged from a low of 46% in February to
a high of 85% in August.
The total spider population varied with two peaks,
similar to those observed in the state-wide survey.

The

spring major peak occurred in April and the minor peak
occurred in August.

The major peak accounted for approxi­

mately 19% of the total and the minor peak accounted for
11 %.
To facilitate the handling of the data,

the same

method used in the state-wide survey was used h e r e .

The

five species representing the most frequently encountered
animals were Steatoda triangulosa, Achaeranea tepidarioru m ,
Chiricanthium inclu s u m , Steatoda borealis and Tegenaria
domestica, representing 450 specimens or 72.0% of the 625
total.

These five species represent four web spinners and

one non-web spinner, Chiricanthium inclusum.

45
TABLE 4.— Taxonomic Listing Local Spider Survey.
Family

Genus

Species

Theridiidae

Steatoda
n----

borealis
triangulosa
grossa

Crustulina

stricta

Achaeranea

tepidariorum

Unknown

sp.

Dictynidae

Dictyna

sublata
sp.

Salticidae

Phidippus
Sitticus
II
II
Salticus
Metaphidippus
Maevia
Metacyrba

audax
palustris
floridanus
pubescens
scenicus
sp.
inclemens
undata

Pholcidae

Pholcus
Spermophora

phalangeides
meridionalis

Gnaphosidae

Herpyllus
Zelotes
Gnaphesa

ecclesiasticus
subterraneus
muscorum
sp.
mger
depressus
sp.
cornutus
sericatus
diadematus
cavatica
undata
diadema
dumetorum
sp.

Araneidae

Drassylus
II
Drassodes
Aranea
II
II
11

II
II
II
II
Argiope

argentata

46
TABLE 4.— Continued.
Family

Genus

Species

Clubionidae

Chiricanthium

inclusum
mildei
sp.
descripta
trilineata
abbotti
obesa
sp.
ruber
tranquillas
sp.

fl
fl

Castaneira
ii

Clubiona
If
VI

Trachelas
IV

Thomisidae

Misumena
Philodromis
IV
VI
II

Xysticus
•V
II

Misumenops
Unknown
Linyphiidae

Linyphia

vatia
pernix
rufus
placidus
vulgaris
sp.
elegans
ferox
funestus
oblongus
sp.
sp.

Unknown

marginata
sp.
sp.

Scytodidae

Scytodes

thoracica

Agelenidae

Tegenaria
Agelenopsis
•1

domestica
pennsylvanica
potteri
sp.
medicinalis
j uvinalis
calcaratus

If

Coras
Wadotes
Lycosidae

Lycosa

avida
helluo
punctulata
moesta
sp.

47

Figure 4.— Temperatures both inside and outside metal build­
ings with relative humidity inside buildings com­
pared with monthly changes in spider numbers
captured.
.......
—
- —
--------------

inside temperature
Outside temperature
Relative humidity
Percent of spiders occurring each month

Degrees F, Percent Relative Humidity
Ul

1972
•b.
00

|
1973

Tl

Percent of Total

49
Figure 5 represents the monthly breakdown for each
species by number of animals and sex proportions.

The two

peak phenomenon was again present but not to the extent as
found in the state-wide survey.

The most numerous species,

Achaeranea t e p i d a r i o r u m , had one major peak in May and then
gradually decreased in frequency from a high of 1 2 speci­
mens to a low of zero in December.

Females again proved

to be the most numerous, with immatures a very close second
(Table 5).
Steatoda t r i a n q u l o s a , a tangled web spinner, of which
133 specimens were captured during the survey, displayed a
spring peak composed mainly of females.
and June,

During April, May

females and immature forms were captured but no

mature males were captured.

The preponderance of speci­

mens captured during the early spring were mature females,
tapering off in numbers through the fall.
of the summer through late summer,

F r o m the middle

the numbers of immature

specimens increased as the numbers of mature specimens d e ­
creased.
Chiricanthium i n c l u s u m , a- wandering or vagabond
spider, was captured throughout the year, with the majority
of the specimens being females.

Immature forms were cap­

tured throughout the year, with a peak coming in spring and
decreasing through the early summer.
both male and female,

The mature specimens,

followed the same general pattern but

50

Figure 5.— Proportional breakdown by sex and maturity level
of most frequently each of the top twelve species.

|i * i | = Females

□

= Males
= Immatures

Nunbor o f A n l w l s (N)

o

.

8

8

E

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8

8
r

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-mm*&wam////

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w,i?A>As&mmm m//

wKg£8i8$i&

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V/
wisssB!
<0
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52

TABLE 5.— Sex Breakdown for Five Species Most Frequently
Captured in Metal Buildings
Species

Females

Males

Immatures

55
35%

33
21%

33
44%

157
34.9%

S. triangulosa

63
47%

37
28%

34
25%

133
29.6%

C. inclusum

39
42%

16
17%

37
41%

92
20.4%

T. domestica

13
35%

6

18
49%

37

16%

9
30%

5
17%

16
53%

30
6.7%

180
40%

21%

A. tepidariorum

S. borealis

97

179
39%

Sum

8

450

Totals and percentages for the top five species
captured in the two metal buildings.

.2 %

53
with many fewer specimens.

The males were captured in much

lower numbers than either the females or the immatures.
Steatoda b o r e a l i s , another tangled web spinner, was
taken only during seven months of the year.

The majority

of the specimens were immatures, with mature males taken
only during April, July and August in low numbers.

The

same pattern of numerical increase and decrease was noticed
though in a smaller scale regarding males,
matures.

females and im­

The immatures were the first captured in the

early spring,

followed by a few matures then and an increase

in the numbers of immatures through the fall.
Tegenaria domestica, a funnel web spinner, was col­
lected during all but three months of the year.

The major

peak occurred during April and May, with the minor peak oc­
curring during August.

Females were dominant in numbers

through the study, with the immature forms captured less
frequently and the males captured in the lowest numbers.
When the local study was analyzed from the viewpoint
of animals per square foot

{Table 6 ) several factors became

apparent regarding the effects of building type on resident
spider populations.
type.

The results are presented by building

In each of the appropriate sections, evaluations were

made of the similarities and differences between buildings
regarding the numbers of animals per 1 0 0 square feet both
by building type and species of spider.

To facilitate the

54
evaluation,

three periods were selected during the study for

detailed analysis.
major peak,

The three periods were the months of the

the minor peak and the month during the summer

when the spider densities were lowest.
The major peak came during April,

accounting for 114

specimens from the five most numerous species collected.
The densities ranged from a high of 0.46 animals per 100
square feet for Achaeranea tepidariorum to a low of 0.04
animals per 100 square feet for both Steatoda borealis and
Tegenaria d o m e s t i c a .

Chiricanthium i n c l u s u m , the third

most frequently encountered species,
of 0 . 2 2 animals per 1 0 0

occurred in densities

square feet.

August was the minor peak month with a total of 53
specimens ranging in densities from a high of 0.41 for
Achaeranea tepidariorum to a low of 0.0 3 animals per 100
square feet for Tegenaria d o m e s t i c a .

Chiricanthium inclusum

had a density of 0.09 per 100 square feet.
The month of the summer high temperature was July
when the temperature reached 81 degrees F. and during which
57 specimens were captured.

Achaeranea t e p i d a r i o r u m , again

was the most dense with 0.36 animals per 100 square feet.
Tegenaria domestica was low with a value of 0.0005 animals
per 100 square feet.

Chiricanthium inclusum had a density

of 0.08 animals per 1 0 0

square feet.

55
The values of the majority of the species changed
as expected from one sample period to another.

As the tem­

perature changed, so did the animal densities.

The two spe­

cies, Steatoda borealis and Tegenaria domestica did not
alter their densities in moving from the spring major peak
to the summer low density, but did change when moving to the
fall minor peak.
When the weather parameters are considered with the
spider populations found within the metal buildings, several
points became clear.

First,

the temperature inside the

buildings seemed to have little effect on either causing
invasion by spiders or maintaining the populations once in­
side.

The main effect of the inside temperature was that

of allowing the spiders to survive once they made the move
in.

The spider population follows the changes in outside

temperature and percent relative humidity.
Wooden Building
There were 462 specimens taken representing 12 fam­
ilies, 32 genera and 56 species, or 13.8% of the total study.
The building sampled was a single story office building
located on the Michigan State University campus, containing
1125 square feet.

This represented 0.4 09 animals per square

foot per year.
Figure 6 displays the weather parameters plotted
against the monthly spider catch.

TABLE 6 .— Numbers of Spiders per 100 Square Feet in Two Metal Buildings.
Metal Buildings 1950 Sq. ft. each, 3800 Sq. ft. total.

Species

Major Peak April
1
2
#/Mo.
#/100 sq. ft.

Minor Peak August
1
2
#/Mo.
#/100 sq. ft.

Summer Low Peak
1
2
#/Mo.
#/100 sq. ft.

A. tepidariorum

35

0.44

17.85

0.23

17

0 .22

S. triangulosa

36

0.46

24

0.31

28

0.36

C. inclusum

17

0.22

7.0

0.09

6.0

0.08

S. borealis

3

0.04

3.0

0.04

0.3

0.004

T. domestica

3

0.04

2.0

0.03

0.4

0.0005

1-The total number of animals taken per month.
2-The number of individuals per 100 square feet of available surface search area during
the sample period.

57
The same families were captured in the wooden build­
ing as those found in the metal ones.

Therefore the ratio

of w e b spinners to non-web spinners was the same, 6 web
spinning families to 6 non-web spinners.
The inside temperature,

ranged from a high of 73

to a low of 6 8 , and did not seem to have any correlation
with the numbers of spiders captured.

The two parameters

which seemed to follow the spider number changes were the
relative humidity and the outside temperature.

The relative

humidity values moved in opposite directions from March to
September,

then began to move in a similar direction, rang­

ing from a high of 79% to a low of 45%.
peratures moved in the same manner.

The outside tem­

The time that the spider

numbers and the outside temperatures came into close associa­
tion was during the fall of the year.
The spiders captured showed two definite peaks in
frequency, one during April with 15.5% of the total and
another lesser fall peak in September, with 10% of the total.
When the most frequently captured species were e x ­
amined on an individual basis
came evident.

(Figure 7),

several facts b e ­

There were seven species making up 282

specimens or 61% of the total.

The species found most fre­

quently in the wooden buildings were the same as in the
metal buildings with the addition of Agelenopsis potteri
and Phidippus a u d a x .

The ratio of web spinning species to

58

Figure 6 — Temperatures both inside and outside wooden
building and relative humidity inside bu i l d ­
ing compared with monthly changes in spider
numbers captured.

Inside temperature
Outside temperature
Relative humidity
Percent of spiders occurring each month

35
Percent of Totol

Degrees

F, Percent

Relotive

Humidity

59

85

75
•e

65
\

55

45

25

1972

M o n th s

1973

60

Figure 7.— Proportional breakdown by sex and maturity level
of most frequently captured species in wooden
building.
= Female
= Male
= Immatures

Number of Animals (N)

o

vi

o

vi

fea

VI

5

tn

o

vi

tn

\\m
m / / m

7??TT
sa&iL

a t *
7
m

\
i

m w m

5
s
i

o\
H

62
non-web spinning species is five web spinners to two non­
web spinners, a higher percentage than found in the metal
buildings.
The three most frequently encountered species of
the above seven were collected throughout the year with the
exception of December.

Chiricanthium inclusum, had a major

peak in late September-early October and a series of lesser
spring peaks in January, April and June.

Steatoda triangul-

ulosa had a major peak in April and Tegenaria domestica
peaked in May.

The minor peaks were in September for

Steatoda triangulosa and October for Tegenaria d o m e stica.
The next three most frequently captured species,
Phidippus audax, Achaeranea tepidariorum and Steatoda
borealis occurred for six to seven months of the year.

P.

audax and A. tepidariorum occurred most frequently during
April, May and June, while S. borealis was found mainly
during May.
Agelenopsis p o t t e r i , while occurring only during
three months of the year, produced

two definite peaks, one

in April and one in September.
As with the previous spider populations from
buildings,

the most numerous stage

by mature females

(Table 7).

metal

was the immature, followed

Mature males, though few in

number, appeared in both spring and fall peaks.

TABLE 7.— Sex Breakdown for Seven Species Most Frequently
Captured in Wooden Building.
Species
C. inclusum
S. triangulosa

Females

Males

Immatures

23
27%

15
17%

49
56%

87
36.8%

7

45
67%

67
23. 8 %
59
20.9%

15

Sum

22%

11%

13

13

22%

22%

33
56%

8

42%

2
11%

9
47%

19
6.7%

A. tepidariorum

7
37%

3
16%

9
47%

19
6.7%

S. borealis

5
33%

1

7%

9
60%

15
5.3%

5
39%

5
39%

3
22%

13
4.6%

76
27%

45
16%

159
56%

T. domestica
P . audax

A. potteri
TOTAL

282

Totals for each species and maturity level for the
top seven species.

64
Spiders present in the wooden building had distinct
differences in both order and frequencies of species when
compared with the populations found in the metal buildings.
Steatoda triangulaosa became the most frequently encountered
species with a density of 0.40 animals per 100 square feet,
as opposed to 0.44 animals per 100 square feet in the metal
buildings, where it was the second most dense species.
Chiricanthium inclusum became the second most frequently
encountered species with a density of 0.31 animals per 100
square feet, as opposed to 0 . 2 2 in the metal buildings.
The lowest density was exhibited by Agelenopsis potteri at
0.01 animals per 100 square feet, as opposed to 0.04 animals
for Tegenaria domestica

(Table 8 ).

The minor peak, which occurred in September, proved
Chiricanthium inclusum to be the most dense with 0.4 7 ani­
mals per 100 square feet, with S. triangulosa second with
0.13 animals per 100 square feet.

Steatoda b o r e a l i s , though

found throughout the rest of the year, was not captured dur­
ing this sample period.
When the densities were considered at both the major
and the minor peak periods,

the densities of all species

considered decreased except C. inclusum which advanced to
a high of 0.47 animals per 100 square feet.

The same pat­

terns were seen when the densities during the summer low
density period was considered.

All species decreased in

densities except T. d o m e s t i c a , which increased by 0.03 ani­
mals per 1 0 0 square feet.

TABLE 8.— Numbers of Spiders per 100 Square Feet in Wooden Building.
Wooden Building 1125 Square Feet.

Species

Major Peak April
1
2
#/Mo.
#/100 sq. ft.

1
#/Mo.

Minor Peak
2
#/100 sq. ft.

1
#/Mo.

Summer Low
2
#/100 sq. ft.

C. inclusum

7.0

0.31

10.6

0.47

4.4

0.19

S. triangulosa

9.0

0.40

3.0

0.13

2.7

0.12

T. domestica

5.0

0.22

1.2

0.05

1.8

0.08

P. audax

0.95

0.04

0.2

0.01

0.2

0.01

A. tepidariorum

0.20

0.01

0.6

0.03

0.2

0.01

S. borealis

0.60

0.03

0.0

0.0

0.3

0.013

A. potteri

0.20

0.01

0.6

0.03

0.7

0.31

1-The total number of animals taken per month
2-The number of individuals per 100 square feet of available surface search area.

66
Brick Buildings
There were 10 brick buildings, with 10,200 square
feet of surface area on two floors plus a partial basement
in each in which 2154 specimens were collected.

This total

gave 0 . 0 2 1 1 animals per 1 0 0 square feet of surface area per
building per year.

The total number of animals produced an

average number of 215 per building for the twelve month
sampling period.
found on Table 4.

The species list for the buildings can be
The ratio of web spinning families to

non-web spinning families was 6 :6 , the same as for the metal
and wooden buildings.
Weather data, Figure 8 , displayed a pattern seen in
the two previous building types.

The spider numbers were

at their peak in the spring, decreased to a summer low and
then had a small fall peak,
into the winter.

followed by a steady decrease

All three peaks occurred during the same

months in all three building types.

The outside tempera­

tures remained the same from one building type to another,
while the inside temperature and relative humidity changed
in a similar manner to that of the previous building types.
The temperature inside varied from a low of 6 8 degrees F
during May and October and attained a high of 75 degrees
F during July and August.

The relative humidity ranged

from a low of 46 percent in February to a high of 82 per­
cent in August.

The trend observed in the two previous

67

Figure 8 .— Temperatures inside and outside brick buildings
and relative humidity inside buildings compared
with monthly changes in spider numbers captured.
-------- Inside Temperature
-------

Outside Temperature

_ __ Relative Humidity
”
Percentages of Spiders Captured

T b to w u r e h i D e s e s

N

$

«

Fna t a r a r
ifl

H um idity

®

^

®

cr>
oo

CO

V

■n

°

w

e

&

P&cent of Towi

69
building -types regarding the changes in the population as
effected by changes in the weather parameters was again o b ­
served h e r e .
From April until the end of September the weather
parameters and the spider populations moved in opposite d i ­
rections.
decreased.

As the temperature increased, the spider densities
In October,

the outside temperature began to d e ­

crease as did the number of spiders captured.
ber on through the spring, generally April,

From Septem­

the spider

populations responded directly to changes in the outside
temperatures and relative humidities.

The temperatures in­

side the buildings, though not directly affecting the immi­
gration rate,

seemed to allow the animals to survive once

the move inside had been made.
The five most frequently captured species produced
a total of 1657 specimens or 76.9 percent of the total taken
from the brick buildings.
C. inclusum

The most numerous species was

(Figure 9) with 572 specimens or 26.8% of the

total collected or 34.6% of the five most numerous species.
A major peak was observed during April followed by a minor
peak during October.
year,

Throughout the major portion of the

immatures were the dominant group collected, with the

majority of these being collected during February and the
months of April through August.

Females were dominant dur­

ing March and October indicating that there may be more
than one generation per year.

70

Figure 9

•Percentages of total numbers of spiders collected
from five most numerous species from brick b u i l d ­
ings .
«•»
I
■ • • #
ilil = Female
= Male
= Immatures

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9-92

72
{3. t r i a n g u l o s a , of which 507 specimens were cap­
tured, was a species that appeared in all of the previous
buildings.

The 507 animals represent 2 3.6% of the total

for the study and 30.6% of the top five species.

Through­

out the study this species had the immatures stages as the
most numerous of all,
males

(Table 9).

peak in September.

followed by the famales and then the

The major peak was in March with a minor
The spring peak was primarily females,

followed by immatures and then males,
for the entire study.

the trend observed

The fall minor peak was evenly d i ­

vided between females and immatures, w i t h 205 of the total
being males.

From April through the fall, the majority of

the animals captured were immatures, making up as much as
62% of the monthly total.

This number decreased steadily

until September when the immatures and females were evenly
divided.

This even relationship can be attributed to the

mortality 'amongst the immature forms.
S. b o r e a l i s , another tangled web spinner, occurred
in lower numbers but was found within dwellings throughout
the year as opposed to the other two more numerous species.
Major peaks occurred during two months, March with 40 speci
mens and May with 44 specimens.

The minor peak occurred

during October with 2 3 specimens.
The two major peaks were not similar in their sex
ratios.

The first peak occurred during March and consisted

of all three stages, evenly distributed.

The second peak

which occurred during May was 6 8 % immatures, 20% females
and 12% males.

The fall minor peak occurred during Septem­

ber and consisted of 77% immatures,
males.

20% females and 3%

Figure 9 gives the proportions for this portion

of the study.

Even during the middle of the winter,

from

November through February there were large numbers of im­
matures and females captured.

There were only eleven

mature males captured during this period,

including Novem­

ber during which there were none collected.
A. t e p i d a r i o r u m , a web spinning member of the family
Theridiidae, was captured during 10 months of the year, e x ­
cluding December and January, during which no specimens
were captured.
October,

The major peak occurred during the month of

accounting for 33 of the 188 specimens captured

for the species.
were females,

Fifty-four percent of the October total

14 percent males and 32 percent immatures.

The minor peak occurred during May and June, accounting for
48 of the 188 total specimens.

Immatures here accounted

for 1 2 percent of the total, or 2 0 animals.
5**

d o m e s t i c a , a funnel web spinner belonging to the

family Agelenidae, was only captured during eight months
of the year, with 97 animals captured.

The major peak o c ­

curred in April when 25 specimens were captured, where 44
percent were immatures,
cent males.

28 percent were females and 28 per

The minor peak occurred in October when only

74
TABLE 9.— Sex Breakdown for Five Most Frequently Captured
Species in Brick Buildings.
Species

Females

Males

Immatures

Slims

C. inclusum

159
29%

75
14%

338
57%

572
35%

S. triangulosa

173
34%

71
14%

263
52%

507
31%

S. borealis

81
28%

48
16%

163
56%

293
18%

A. tepidariorum

77
41%

23

88

12%

47%

11%

32
33%

21
22%

44
45%

97
5%

522
32%

238
14%

876
54%

T. domestica
TOTALS

188

1657

The totals and breakdowns by sex and maturity levels
as percentages of the total for the species.
Also the per­
centage of the total for the brick buildings.

five specimens were captured#

two females and three immatures.

The sex ratios for the brick buildings#

Table 9, indicate

that immature forms account for almost half of the speci­
mens captured#
22

45 percent immatures,

33 percent females and

percent males.
Brick buildings were the most numerous structures

sampled but consistently had the lowest numbers of animals
(Table 10).

The differences in densities of animals often

differed by a factor of 1 0 to 1 0 0 times lower than densities
of the same species in the other two building types.
the major peak, C. inclusum was the most frequently

During

TABLE 10.— Numbers of Spiders per 100 Square Feet in 10 Brick Buildings.
Brick Buildings 10,200 square feet each, 102,000 square feet total.
Major Peak
Species

C. inclusum

1

2

Minor Peak
1

#/Mo.

#/100 ft.

#/Mo.

102.96

0.05

63

2
#/100

Summer Low
1

ft.

2

#/Mo.

#/100 ft.

0.03

51.48

0.025

S. triangulosa

70.98

0.036

41

0.02

45.63

0.22

S. borealis

32.23

0.015

23

0 .01

14.65

0.007

A. tepidariorum

15.04

0.007

28

0.01

13.85

0.007

T. domestica

24.25

0.012

5

4.85

0.003

0 .002

1-The total number of animals taken per month.
2-The number of individuals per 100 square feet of available search area.

76
encountered species with a density of 0.05 animals per 100
square feet of surface area.

T. d o m e s t i c a , though never

frequently encountered w h e n compared to the other species
and building types, had a density of 0 . 0 1 2 animals per 1 0 0
square f e e t .
The minor peak dropped C. inclusum to a value of
0.03 animals per 100 square feet.

T. d o m e s t i c a , w i t h a

low value from the major peak, dropped to 0 . 0 0 2 animals
per 1 0 0 square feet.
The summer period during which the spider popula­
tion w a s lowest, which occurred during August, was when
C. inclusum dropped in density to 0.025 animals per 100
square feet of surface area.

This value was 0.005 below

that for the density during the minor peak period.

T.

d o m e s t i c a , the animal with the lowest density in both the
metal and wooden buildings was also the least dense in the
brick buildings.

The density was 0.012 animals per 100

square feet during the major peak and 0 . 0 0 2 animals per 1 0 0
square feet during the minor peak.

The period during the

summer when the spider population was lowest was during
August when the density of A. domestica was 0.003 animals
per 1 0 0 square feet,
peak density.

0.001

animals higher than the minor

77
Predatory Behavior
Prey Contact Distance
Peck and Whitcomb

(1970)

state that C. inclusum lo­

cated prey through physical contact with the extended fore­
legs while traveling in a forward direction.

The results

of this portion of the study agree with their investiga­
tion.

When the spiders were exposed to prey at various

distances and their attack responses were noted,
cal distance was between 0.5 cm. and 1.0 cm.

the criti­

When the

spiders were exposed to prey at distances greater than 1 . 0
c m . , the response by matures and immatures alike was iden­
tical to the nonexistance of prey situation.
Effects of Light on
Hunting Behavior
The results of this study indicate that light has
a very negative effect on the tendencies of the spiders to
wander about.

Satiated spiders, particularly mature males

and females, do not usually hunt when the light levels ad­
vance above eight foot candles.

Figure 10 shows that the

acitivity curves for males and females do not differ sig­
nificantly.

The curve for the immatures indicates that

they are active in low light levels as well as levels
higher than those tolerated by the adult spiders.
The effects of starvation increased the apparent
tolerance levels of all classes of spiders towards light.

78
The numbers of animals hunting in the lower light levels
does not increase noticeably from the fed animals, but at
higher levels a noticeable increase in activity takes place.
Mature male spiders, even though starved,

followed the same

patterns as the satiated spiders except that they were a c t ­
ive at higher light levels.

Mature females increase their

hunting activities from a high of eight foot candles in
satiated animals to 1 2 foot candles in starved animals.
Immatures were noticed to be more active in higher light
levels even when satiated and display the same tendencies
when starved.

These animals were found outside their rest­

ing cells and actively hunting even when the light levels
exceeded 1 2 foot candles.
Under normal

feeding conditions,

hunting behavior

could not be elicited unless the light levels were lower
than four to six foot candles.

The degree of drop in the

response curve was steepest from four to the eight foot
candle level in the satiated animals.
animals were examined,

When the starved

the curves were quite different.

The steep parts of the curve were extended to the eight to
12 foot candle level.

The effects of starvation can force

the animals out of their resting cells and assume a hunting
behavior.
During broad daylight,
the spiders:

three things could activate

first, a severe hunger level;

second,

the

79

Figure 10.— Numbers of spiders remaining active before and
after starvation observed at different foot
candle levels.
------- = Female
= Male
--------= Immatures

80

10
Satiated

spiders

8

0

0

2

Number

4

6

8

ID

12

Foot Candles

of

Specimens Ac tiv e

6

10

i)8 Hour Starvation

8

0

0

2

4

6

Foot Cahjles

8

10

14

81
active searching for a mate by either the males or females;
and third, the disturbance of a resting cell such that the
animal is forced to vacate it.

The response to the rest­

ing cell disturbance was to flee the source of disturbance,
move about for a short time searching for another hiding
place and becoming quiescent when the disturbance ceased
or a hiding place was found.
C. inclusum reacts in a negative phototropic man­
ner.

The spiders seem to be able to detect the movement

of shadows when they are active in subdued light.

When

an object moved between the light source and the animal
caused a shadow to move across the animal, an evasive re­
sponse was elicited.
Prey Moisture Content
Prey moisture, an often overlooked portion of the
ecology of spiders and other animals, has been shown to
have certain effects on maintaining the normal condition
of spiders.

Assuming that spiders which overwinter and

remain active in dwellings have little access to water
supplies and assuming the relative humidity within heated
buildings was fairly low, spiders which are able to sur­
vive must have an alternate source of moisture.
Throughout this study, no water was given to the
animals in any form except that which they were able to o b ­
tain from their food sources.

Figure 11 shows the number

82

Figure 11.— Three graphs showing the number of individuals
dying for each of three hunger stress periods.
------- = Female
= Male
= Immatures

83

Y- 0.46k + 0.28
Y- 0,34k + 0.13
Y - 0.63k + 0.5*1

3 Day

4

2
0
1

2

3

4

5

6

VfeEKS

Y- 0.54x + 0.27
Y - O.GCk + 0.74
Y- 0.72k + 1.0

6

7 Day

4

2
0
1

2

3

5

6

Meeks

8

Y- 0.26k + 1.4
Y- 0.89k + 0.40
Y- 0.74k + 0.70

6

10

2
0
1

2

3

4
Meeks

5

Day

84
of animals lost for the three degrees of stress for each
sex and the immature s p e c i m e n s .
Beginning with the three day stress period the
slopes for m a l e s , females and immatures are presented.

Re­

gression analysis showed that the equations were not sig­
nificantly different at the 0.05 level even though the
equations were different in both slope and intercept.
the

individual slopes were examined,

the

lowest slope,

the mature

When

females had

followed by the mature males and t]ien the

immatures.

the

When the seven day feeding schedule was

examined,

immature animals again were found to be the

most sus-

ceptable to the effects of moisture loss.
lowed by the females and then the males.

They were fol­
The slopes pro­

vided by the three equations again proved to be non­
significant at the 0.05 level, but were significantly
different at the 0.1 level.

The three slopes placed the

females between the immatures and males this time,

indicat­

ing an increased response to lower moisture levels.
When the 10 day stress period was examined, the
mature males had the steepest slope,

1.26, while the fe­

males had a line equation with a slope of 0.89.

The im­

mature forms did not alter their responses much in moving
from a slope of 0.72 to 0.74.
Following the last two feeding regimens, males died
in greater numbers with the reduced moisture levels.

When

85
the slope differences are compared between the three day
and the seven day regime, there was a difference in slopes
of 0.08.

But when the 10 day regimen was compared with the

seven day regimen, the difference was 0.72.
Females showed less severe responses to reduced
moisture but there was an increased loss due to mortality
for each increase in time between feedings.

The females

in going from the three day feeding regime to the seven
day regime changed in slope from 0.34 to a slope of 0.60,
a net change of 0.26.

In moving to the 10 day schedule,

the net change was 0.29 in going from a slope of 0.60 to
a slope of 0.89.
The immature animals exhibited the least amount
of change in slope when they were examined under the three
periods of stress.

The net changes in slope in moving

from the three to seven and seven to 1 0 day stress periods
were 0.09 to 0.02, respectively.
Data from Peck and Whitcomb

(1970)

and this study

indicate that the spiders can live for at least a period
of three weeks without food.

When water is withheld the

animals seldom live longer than three to five days.
Search Patterns
The analysis of data indicated that the search
patterns of C. inclusum males,
random.

females and immatures were

When the animals were tested before and after

86
food c a p t u r e , the results indicated that the feeding
altered the search patterns slightly, but they remained
random.

This difference was best illustrated with the

mean values plotted for each condition and number of turns.
Assuming the mean value for each of the three runs to be
20,

the values for each run above or below 2 0 were tabu­

lated.

The values for both left and right turns were added

together and averaged.

The resulting value was plotted for

each sex both before and after food capture and before and
after 48 hours of hunger stress

(Figure 12).

In each case,

the values following starvation were much more varied,

in­

dicating a change in behavior following hunger stress.
The degree of change in the deviation from the
mean number of turns was greatest in the mature females,
less in the mature males and there was no change in the
immatures specimens.

Following the 4 8 hour starvation

period, all three classes of spiders increased their devia­
tions from the mean value of 20 turns.

The greatest amount

of change was noticed in the immatures which had a change
of nine,

followed by the mature males with a change of

seven and then the females with a change of five.

Follow­

ing food capture and feeding, the deviation decreased in
all three classes tested.

The most severe change occurred

in the females where the deviation dropped by eight,

fol­

lowed by the immatures with a change of seven and the males
with a change of three.

87

Figure 12.— Graph showing deviation from mean value of
2 0 turns during random search pattern in­
vestigation .

88

Satiated
10

5

0

»—

Before

After

Before

After

Stressed
Satiated

J

Before

10

After

Before

Satiated

After

Stressed

5

0

—

B efore

After

Before

After

[
89

The results of this portion of the study indicate
though the search patterns were random in nature, there
were slight changes in the degree of randomness associated
with changes in the hunger stress applied to the animals.
Under hunger stress the s p i d e r s ' search patterns became
slightly less random.
were allowed to feed,

After the animals captured food and
the amount of deviation from the

mean value was observed to d e c r e a s e .
Resting Cell Study
Part one of the study showed that there was an in­
crease of five resting cells from the initiation of the
study through the 14 day period.
When the analysis of part one of this portion of
the study was completed,

the data indicated that the method

of counting resting cells to determine the number of spi­
ders present would not give reliable results.

On day one

of the study 14 resting cells were observed to contain spi­
ders.

On day fourteen there were 19 resting cells, a net

gain of five cells, or a 36 percent increase.
a net loss in the number of spiders of four,

There was
leaving 1 0

animals and 19 cells.
The second portion of the study was designed to
determine the length of residency in the original cells
and the increase in cells built.
were tabulated and marked.

On day one 14 cells

On day two, three old cells

Figure 13.— Part 1:

Original number of resting cells found
with increase over two week period.

Part 2:

Changes in resting cell occupancy and
new cell construction rate.

----------- _

Number of original cells used and reused.
Number of new cells constructed over
time.

NUMER OF RESTIM6 f o 1*

91

1 2

3 4

5

6 7 8 9 1 0 1 1 1 2

OF fcSTINB CELLS

IkY S

2

3

4
Days

5

6

15

14

92
were abandoned and three new cells were constructed.

By

the fifth day of the study there were as many old cells
as there were new cells.

On the eighth day all of the

original 14 cells had been abandoned and there were 15
new cells constructed since the original tabulation.

The

net change in the number of marked spiders during this
portion of the study changed from 14 on day one to nine
on day eight.

This was a loss of five or 36 percent.

Part three of the study involved the effects of
search area size on the number of spiders returning to the
original resting cells.

The return rate was also tested

against several periods of hunger stress
ginning with satiated animals,

(Figure 14).

Be­

all three classes tested

returned to the original cells an average of 95% of the
time.

This occurred in both the two and five gallon test

chambers.

When the tests were carried out in the 10

gallon aquarium,

the females returned 100% of the time.

Males returned 80% of the time and the immatures returned
60% of the time.
cage was used,

When the six by six by six foot screened

the percentages were lower.

dropped to 40%,

The females

the males and the immatures dropped to a

60% return rate.
The size of the aquarium seemed to affect the pe r ­
centage of animals returning to the original cells.
next factor tested was the effect of hunger.
hours of starvation,

The

Following 48

the same tests were run again.

This

93

Figure 14.— Three graphs showing number of spiders returning
to resting cells in different sized search areas.
X axis denotes search area size.
Y axis denotes percent returning to the resting
cell.
-------------------

Males
Females
Immatures

FT"

•

94

100

25

Satiated Spiders

5 Ga l .

10 Gal .

6*5 Screened Cage

75

48 Hour Stress

P ercent

of

Total Retu r n in g

2 Gal .

2 Gal .

5 Gal .

10 Gal .

6x6 Screened Cage

72 Hour Stress

25-

2 Gal .

5 Gal .

10 Gal .

6*6 Screened Cage

95
time the females returned only 80% of the time in the two
gallon aquarium.

The males returned 100% of the time in

the five gallon aquarium, while the females and the im­
matures returned 80% of the time.

When the 10 gallon

aquarium was used all three classes of spiders returned
80% of the time.

The six by six by six foot screened cage

had all three spider classes returning at the rate of 60%.
Before the effects of hunger were tested on the
return rate, the responses of individual spiders were apt
to vary considerably.

Following the application of hunger,

the animals all acted in a similar manner.
When severe hunger stress was applied to the test
animals,

the aquarium size had a direct effect on the per­

centage of animals returning to the resting cells.
the animals were starved for 72 hours,

When

there was a notic-

able effect on the numbers of animals of each sex and
maturity level returning to the resting cells.

Immatures

were the only animals returning to the resting cells 100%
of the time in the two gallon aquarium.
females returned at the rate of 80%.
size was increased to five gallons,

Both males and

When the aquarium
all three classes

of spiders returned at the rate of 80%.

In the 10 gallon

aquarium the females remained at the 80% return rate while
the males and immatures decreased to a 60% return rate.
At 72 hours of hunger stress in the six by six by
six foot screened cage,

the females return rate dropped to

96
40%, identical to that for the satiated females.

Males and

immatures dropped to a 20% rate.
The overall effect appears to be that aquarium size,
when considered alone, exerts a moderate effect on the aban­
donment of resting cells.

When a starvation alone is con­

sidered, beginning with the two gallon universe over three
starvation regimens, no change takes place in the numbers
of animals abandoning their resting cells.
gallon squarium is considered,

When the five

little change is noticed u n ­

til the 72 hour hunger stress is reached,

at which point

all three classes of animals are at a return rate of 75%.
In the 10 gallon aquarium the ef-fects of starvation begin
to be apparent.

Satiated animals are somewhat more erratic

in their activities than those in the smaller aquarium but
by 48 hours of hunger stress, all the original resting cells
have been abandoned at the rate of 20%.

At 72 hours of

stress the abandonment rate had dropped to 40% except for
the males.

When the screened cage was used,

satiated and

48 hour stresses animals were not significantly different,
but by 72 hours the abandonment rate was 75%.
The overall effect was that the greater the hunger
stress and the further the animals had to travel in locat­
ing and capturing food,

the less likely the animals were

to return to the resting cell most recently constructed.
>

97
Effects of Prey Size
The prey sizes were selected at a percentage of
prey body weight to that of the spider.

The small size

was 1/2 or less than the body weight of the s p i d e r , the
m edium size was greater than 1/2 but less than the body
weight of the spider, and the large size was greater than
the body weight of the spider.
be found in Appendix C.

The statistical data can

Figure 15 displays the results

in the three starvation experiments.
Spiders starved for 24 hours had a marked prefer­
ence for specific size classes.

The effects of spider

sex and maturity level were also significant but at a lower
significance level.

Mature males tended to attack all

size classes with more frequency than the females and im­
matures.

Females followed the same selection pattern but

at 10% lower rate of ingestion.

Immatures began at the

same level as the females, but decreased at a greater rate.
At this level of starvation,
significant at the

the effects of prey size was

.005 level, while sex of the predator

was significant at the

.05 level.

When the spiders were subjected to 4 8 hour starva­
tion stress, the noticable change in prey size attacked
was significant.

The males did not change their attack

rates for the small and me d i u m size classes but when the
large size class of prey was introduced,

the attack rate

98

Figure 15.— Percent attack rates for three classes of
spiders under three hunger stress regimes.
— — = Female
■------ = Male
—— ----

Immatures

99

100

Large

100

20

48 Hour Stress

Medium

Large

60

20

Sh a ll

Large

100
Increased from 60% to 80%.

An increase was also noted in

the females, where the increase was from 50% to 60%.

The

immature spiders increased their attack rates from 40% to
50%.

These results indicate that the spiders will increase

their attack rates with an increase in hunger stress regard­
less of sex or maturity level.
The effects of hunger on the size of prey attacked
increased when the stress reached 72 hours.

The most no tice­

able increase occurred among the mature females.

There was

no difference when the small prey size was offered, but
when the me d i u m sized prey was offered,
increased from 70% to 90%.
offered,

the attack rate

When the large sized prey was

the attack rate increased from 60% to 80%.

the immature spiders were examined,

When

their attack rate d e ­

creased to that of the 24 hour stress period.
When t h e results of the entire investigation were
considered,

there was an increase in the size of prey at­

tacked and eaten associated with an increase in hunger
stress.

This increase affected the mature specimens to a

greater degree than the immature specimens.

The statisti­

cal analysis indicated that the effects of the sex of the
spider attacking the prey was barely significant at the 0.1
level.

The size class of the prey proved to be non-signifi­

cant at the 0.1 level.

This indicates that the predators

would attack almost any size class w i t h minimal selection.

101
The interactions between the sex of the spider and the prey
size proved to be barely significant at the 0.1 level.
Distances Traveled
Study
The distances that C. inclusum travels during a
foraging period has been shown to be related to sex of the
spider, maturity of the spider and to what extent it has
been stressed by hunger.

Mature male C.

inclusum speci­

mens have been shown to wander in excess of 2400 feet d u r ­
ing a 10 hour foraging period.

The mean value for the

animals tested was 1940 feet during the same length of
time

(Figure 16).

As the stress of hunger was applied to

the animals, a steady decrease in the distances traveled
was noted.

As the stress increased from satiated spiders

to those without food for five days,
in a regular manner.

the distances decreased

When the mean values for each stress

period were plotted and a regression line fitted, the eq u a ­
tion for the line was Y = -2.91X + 16.39.

In looking at

the mean values of the distances traveled at the individual
stress periods,

it can be seen from Figure 17 that from

the fourth day of stress onward, the mini m u m distances had
apparently reached a minimum.
proximately zero.

The slope of the line is a p ­

The correlation coefficient between

starvation and distance traveled is quite high at 0.943.
The coefficient of determination was 0.88 9, again quite
high.

102

Figure 16.— Distances traveled by three classes of spiders
under six hunger stress regimes.
Y axis de­
notes distances traveled in feet, multiplied
by 100.
X axis denotes six regimes.
r
r
Y

= The Correlation Coefficient.
2

= The Coefficient of Determination.
= The equation for the line represented by
the six mean values of the feeding regimes.

103

20

R ■ 0.9*1

15

. Y ■ -.29b< +16*4

10
5

Distances Travels

in Feet (Times 100)

0

0

1

2

3

4

5

fknjRE Females

20

R ■ 0.96

15

Y * - 15.9b( + ID

10
N v

5

•

•

*---

Y - -8.4*+ 11.8
R ■ 0.70

20
10
5
0

0

1

2

3

Days op Starvation

4

5

104
The mature females had a maximum distance traveled
equal to 1925 feet, somewhat less than the mature males.
The mean value for satiated females was 1125 feet, which
decreased through the individual stress periods to a low
of 270 feet after five days without food.

As can be seen

from Figure 17, the range of distances for the females is
wider at the more satiated levels and then decreases when
the hunger stress is increased.

The equation for the line

representing the plot of the mean distances traveled is
Y=

-1.59X + 10.05.

The coefficient of correlation between

the distances traveled and the hunger stress effects was
0.96 3, higher than that for the mature males.
ficient of determination was 0.928.

The coef­

Both these values are

very high and indicate a close relationship between dis­
tances traveled and the effects of hunger stress.
The immature specimens displayed a less direct
response to the effects of hunger stress.

The distances

traveled through the stress periods were not consistant.
The correlation coefficient was lower than either the males
or the females at 0.7 04.

The coefficient of determination

was also lower at 0.496.

The mean distances at each of the

stress periods did not produce the decreasing slope of the
males and females.
+ 11.83.

The equation for the line was Y = -.84X

The responses of the immatures to stress proved

to be less predictable.

105
When the investigation is considered in its en­
tirety, the mature males have the more direct response to
hunger stress,

followed by the mature females and then the

immature specimens.

When the correlations between stress

and distances traveled are examined,

the females have the

most direct response followed by the males and then by the
immatures.
Prey Density Study
These experiments were designed to determine the
effects of both prey and predator densities on the ability
of the predators to capture prey.

The design of the ex­

periment was to manipulate prey densities within four
search areas of increasing size.
methods section,

As explained in the

each area was tested using one predator

at each of five prey densities.

As a result there were

several redundancies in prey densities as the area sizes
were increased.

Therefore,

specific densities were se­

lected from different area sizes to give a series of prey
densities which would increase in an approximate geometric
manner.

Table 11 gives the values for the situations in­

cluding one,

two and four predators per search area.

From

inspection of the table, the prey densities roughly double
from one animal per 14.8 square inches to a low of one prey
per 2960 square inches in eight density changes.

106
Operating under the assumption that these spiders
hunt in a random manner, with a known increase in prey dens­
ity there should be a corresponding decrease in predation
time for a corresponding decrease in available search area.
As the time to capture prey changed from the high to the
low density,

a straight line relationship developed.

Fig­

ure 18 gives the curve and the equation for the data.

The

equation for the line is Y = 0.8 3X + 62, with a correlation
coefficient of 0.848.

The high correlation coefficient

supports the contention that a straight line relationship
exists between search time and prey density.
The question arises that if there is a 1:1 relation­
ship between the search time and the prey density,

should

not the slope of the line be 1.0 instead of 0.83?

One e x ­

planation for this difference is that the majority of the
tests were run in the small tanks where the possibility of
encountering prey would be increased with a reduction in
search time.
When the stress of increased predator numbers was
considered,

several patterns emerged regarding changes in

slope and intercept of the e q u a t i o n s .

When the predators

were increased from one to two per search area,

the assump­

tion was that the slope of the line would decrease by one
half.
balism.

This assumption was made on the basis of zero cannaF r o m the results of previous observations, canna-

b a l i s m among adults was practically n o n - e x i s t a n t .

With

107
TABLE 11.--Time to Initial Capture for Predators in Differ­
ent Densities and Prey in Different Densities.
Tank Size

Surface Area

? ™ X « Ure
xn ™
mxnutes

1 Predator/Universe
10
10
5
5
2
2
5
2

gal;
1:1
gal;
2:1
gal;
1:1
gal;
2:1
gal;
2:1
gal;
4:1
gal; 20:1
gal; 20:1

2960
1480
740
370
148
74
37
14.8

285
215
145
145
105
62
48
15

2960
1480
740
370
148
74
37
14. 8

93
85
60
55
65
35
12
10

2960
1480
740
370
148
74
37
14. 8

78
108
35
35
18
12
12
5

2 Predators/Universe
10
10
5
5
2
2
5
2

gal;
1:1
gal;
2:1
gal;
1:1
g a l ; 2:1
g a l ; 2:1
gal;
4:1
gal; 20:1
gal; 20:1

4 Predators/Universe
10
10
5
5
2
2
5
2

gal
gal
gal
gal
gal
gal
gal
Gal

1:1
2:1
1:1
2:1
2:1
4:1
20:1
20 :1

108

Figure 17.— The three predator densities over available
searching area at different prey densities.
r = The Correlation Coefficient.
Y = The equation for the line representing
the plotted points.

109

320
1 Predator /S earch Ar e a

280 •

/'

Y - O.ffifc + 62

240

r

200

- 0.949

160
120

/

H

/

80
V -

40

90

2

*

*

?

£

S

I

I nitial Capture

Search Area in S quare I nches

80
70H
60

2 R o a t o r s /S

earch

Ar ea

Y -0.24*+ 34
R - 0.793

30

o
t

40

Minutes

30

in

120

T ime

20

103

00
73
60

10
4 P redators /S earch area

•

Y ■ 0.29k ♦ 17
R - 0.806

43
30

15

i *s

*

2

*

*

SfewcH Am *

g

2

I

S e a rc h A rea in S q u are l i n e s

!

n

in So m e

i
hoc*

|

110
zero cannabalism and two predators per search area,

the data

produced a line with the equation of Y = 0.237X + 34.57.
This does not meet the assumption of a 50% reduction in the
slope of the line.
The interesting point, however,

is that when the

number of predators was increased from two to four,
equation of the line was Y = 0.28 7X

+

16.99.

the

The slope

of this line was very near the slope of the line for the
two predator case.

The difference between the two equa­

tions was in the Y intercept,

in which the four predator

case had an intercept very nearly that for the two preda­
tor case.

When the two equations were plotted together,

the apparent difference was that the two predator case
operates at a slower rate.
When the correlation coefficients were examined,
they were found to differ by only 0.015, which is a small
difference in light of the sample sizes and the number of
re p l i c a t i o ns.
When the entire density study is considered, C.
inclusum apparently behaves in a

predictable manner when

predator densities exceed two per search area.

When the

densities fluctuated between one and two predators per
search area, apparent behavioral acitvities tended to
render the spiders unpredictable.

DISCUSSION

Examination of the spider species found within
dwellings in Michigan during the local survey indicated
that there were many species of spiders able to invade
dwellings and to occur there for varying periods through­
out a calendar year.

However, when the quantitative as­

pects of the spider species were examined,

there was a

reduction in the numbers of species containing large num­
bers of individuals through the year.

The species were

ranked in order of the number of individuals captured by
building type in descending order.

The species making

up 50% or more of the total numbers of animals were ex­
amined in detail to determine changes in the density and
population structures throughout a calendar year.

In

conjunction with the animal survey, three environmental
parameters were measured at the same time as the spider
survey.
The parameters measured were the temperature in­
side the buildings,

the percent relative humidity inside

the buildings and the temperature outside the building.
The parameters were related to the spider populations in
several ways.

The initial effect of the temperatures was

111

112
whether they were the cause of the increase in spider nu m ­
bers or whether they were responsible for the continued
existance of the animals within the particular dwelling.
The outside temperature, though not a direct in­
fluence on the spiders once the move was made inside, was
used as a measure of the degree of movement evidenced by
the spiders.

As the temperature increased in the spring,

so did the numbers of spiders.

The change was from a low

of 32 degrees during December when there were 27 spiders
captured.

As the temperature increased in the spring

months from the minimum, so did the number of spiders.
There seemed to be no absolute temperature when the spiders
began their movement indoors or o u t d o o r s .

The changes were

gradual in both temperature and the numbers of spiders cap­
tured.

The upward changes in both temperature and spider

density continued until April when the spider densities
began to decrease.

This change in direction continued un­

til August when another change in density took place.

Du r ­

ing October the directions of the curves again coincided
and continued so until the end of the study.
The two parameters that helped maintain the spider
populations during the periods of adverse conditions were
the temperature inside the dwellings and the relative humid­
ity.

The latter seemed to move in the same directions as

the outside temperature but without the same degree of

113
change.

When the relative humidity and the temperatures

inside the buildings were considered at the same time,
there appeared to be an environment more suitable for the
continued habitation by the spiders.
The results of this portion of the study indicate
that the temperature outside affects the spiders to the
extent that they either must escape to a more protected
area or die.

The two parameters inside the buildings

allow those spiders that have made the move the opportu­
nity to survive in an active state unless some factor
present indoors kills or removes them or their food supply.
The fact that spiders were found in the character­
istic two peak pattern can be explained in several ways.
The life cycles of many spiders follow the pattern of m a t ­
ing and the laying of eggs in the spring and early summer,
overwintering as penultimate instars with maturation and
m ating in the spring again
Dondale 1961).

(Gertsch 1949, Comstock 1948,

This cycle, when considered in a numerical

sense, can account for population fluctuations in the fol­
lowing ways.

In the spring there is an increase in both

numbers of animals as they emerge from the winter estiva­
tion coupled with the high degree of mobility associated
with the active searching for mates by the mature spiders.
These facts are all associated with the favorable conditions
found during the spring and early summer.

114
As the numbers of immatures increased during the
summer and early fall there was a drop in the numbers of
both mature males and mature females captured.

Moulder

et a l . (1970) have found that there is an increase in the
numbers of immature animals in the months of May and De­
cember.

The increase during May can be explained as due

to the numbers of animals newly hatched and their increased
mobility.

The increase during the month of December is

harder to explain as the winter months were usually the
poorest in numbers of animals captured.

My data indicated

that the two peaks were composed mainly of immature speci­
mens and mature females.

The spring peak being mostly

mature females and the fall peak was mainly immature speci­
mens.
The absolute numbers of immatures were found to re­
main relatively constant during the latter months of the
year.

When the numbers were considered as percentage

values of the totals for each month, the immatures seemed
to increase in number.

This was due to the gradual de­

crease in number of both males and females.

These results

confirmed the hypothesis based on the understanding of
spider life cycles.
When the three building types were considered with
the most frequently captured species, the same patterns
emerged.

The major peak occurred in April consisting

115
mostly of females and i m m a t u r e s .
duced during the summer months,

The population was re­

increased to a lesser peak

during the fall and decreased to the low period of the
year during the winter months.

The five species most

dominant in the metal buildings,

the seven in the wooden

building and the five in the brick buildings all followed
the same pattern, that of spring major peaks followed by
summer low densities and a smaller peak in the fall fol­
lowed b y a reduction in numbers to almost zero.
The densities of spiders on a square foot basis
were examined to assess the actual numbers of animals at
specific times during the year.

The three time periods

selected were the spring major peak,

the summer low density

period and the fall minor peak period.

The densities per

100 square feet indicate that there were only two species
out of the many frequently captured that provide the most
animals.

The top two species,

though not the same in all

three building types, were within the four most frequently
captured species.

The top three species in all three

building types were composed of two web spinners to one
wandering or non-web spinning s p e c i e s .
C. inclusum,

the species of concern throughout the

study, was captured in densities varying 0.05 animals per
100 square feet in the brick buildings to a high of 0.3
animals per 100 square feet in the wooden building.

The

116
two metal buildings had a density of 0.22 animals per 100
square feet.

When these values are compared with the spe­

cies most frequently captured during the study, £3. triangul o s a , w h ich had a density of 0.40 in the wooden building
and 0.44 in the two metal buildings,

it was found that

these two species were always present during almost the
entire year and the proportions of males to immatures to
females held relatively constant.
W h e n considering the third most frequently captured
species on down to the least frequent of the detailed ones,
the densities were smaller by a factor of from 2 to 45
times.

The least frequently captured species in both the

metal and brick buildings was T. d o m e s t i c a , with S. borealis
in both the metal and wooden buildings.
When the remaining two periods were examined,
same order within the species was retained.

the

In other words

the placement of the species in order of densities was the
same from one sampling period to another within a particu­
lar building type.
Size of the spiders was at first suspected as a
potential means of explaining the make up of the popula ­
tions with particular dwellings.

The hypothesis being

that the smaller more inconspicuous species would attract
less attention and thus be less susceptable to predation
or removal by humans.

Of the three most frequently cap­

tured species within the three building types none can be

117
considered as small spiders.

C. inclusum ranges up to

three-quarters of an inch as a mature animal, while T.
domestica approaches the same dimension, with S. tr i a n g u l o s a ,
a slightly smaller spider at one-half inch.
An interesting point regarding the movement of •
spiders into dwellings is that even though the sampling
method used called for removal of all possible specimens,
there were always more spiders being captured even during
the w i n ter months.

This indicates that even though there

was a good possibility that all specimens were not captured,
enough were removed each time so that similar populations
could not become established between sampling periods,
cluding invasion.

ex­

This indicates that there must be a

continual movement of spiders into dwellings throughout
the year,

including the winter months.

This constancy of

numbers would also indicate that the prey densities will
support only that number of animals so that there would
not be a large number of animals similar to the spring and
fall densities.

There apparently is no concerted effort

by the spiders to move indoors, but the move indoors does
allow those that make it to extend their survival beyond
that of those remaining o u t d o o r s .
The conclusions of this portion of the study are
that only a very few species,

in most cases from five to

seven, are able to maintain themselves within dwellings

■e

■

■

118
over time.

Of this number, three make up the majority of

specimens captured in the ratio of two web spinners to one
non-web spinner.
considered,

When the effects of building type was

there was no apparent effect,

as the species

were the same from one building type to another.

The only

differences were in the order of frequencies of the most
common species.

The environmental parameters appeared to

have only a slight effect on the

spider numbers once the

move had

been

made indoors.

The outside temperature e f ­

fect was

that

of a driving force causing the spiders to

move and

also

aid in the maturation process.

The results of the state-wide survey reinforce the
conclusions drawn from the local quantitative survey.

There

were 12 species captured that made up more than 50% of the
total number of specimens.

Seven of this number were common

to the three building type species list from the local survey.
The remaining five species were A. sericatus,

S. s c e n i c u s ,

T. t r a n q u i l l a s , H. ecclesiasticus and A. p e n n s y l v a n i c a .
Of this number, there was only one new family added.

This

was the Gnaphosidae which contains the species H. ecclesi­
asticus .

T. tranquillas belongs to the family Clubionidae

as does C. i n c l u s u m .

A. sericatus has been eliminated from

the discussion because there was only one time when the
specimens were captured and turned in.

This represented

70 of the 7 3 specimens which were captured in one day from

p
119
a warehouse in Detroit.

This sample tended to bias the

sample and the results of that portion of the study.
The differences between the two studies were sig­
nificant only when the relative frequencies of the species
were considered.

In the local survey, the most frequently

captured species in one building type were not the most
frequent in the next.

The same principle held true for a

comparison between the state wide and local surveys.

The

most frequently captured species in the state-wide survey
was from first through third in the local survey.
the entire study was considered,

When

the fact that the top

seven species in the local survey were the top seven spe­
cies in the state-wide survey,

the conclusion that only a

few species were able to invade buildings successfully was
reinforced.
The results of the predation study, when combined
with the results of the Peck and Whitcomb study, give a
more detailed view of the basic biology and behavior traits
of the spider as found in the state of Michigan.
C. inclusurn, a clubionid wandering spider, has been
shown in the past to have a single generation per year when
found in the natural habitat.

However, the results of this

study and the results of the two surveys indicate that
there is a possibility that two generations are possible
when the spiders remain indoors through the winter.

This

120
is evidenced by the fact that matures were found late in
the season as well as immature forms.

If only one genera­

tion was to found, there would be distinct times when the
mature forms would dominate and other times when the im­
matures would be dominant.

There is enough overlap in

the occurance of both matures and immatures that the two
generation per year or at least an overlap of two genera­
tions idea can be considered.
The behavior associated with food location and cap­
ture is presented and discussed as follows:
Adult and immature specimens of C. inclusum have
been tested and found to require a contact distance of
less than 0.5 cm. before prey can be located under normal
hunting conditions.

When this small contact distance is

coupled with habit of the animals to hunt during the night
hours an interesting behavior pattern becomes apparent.
The more light that was applied to the animals, the less
the hunting activity was observed.

The mature forms were

less likely to be hunting when the light levels exceeded
eight foot candles than when the light levels were below
eight foot c a n d l e s .

Immature specimens were observed

hunting in slightly higher levels.

This tendency on the

part of the immature forms to be a little less predictable
also held true when the stress of starvation was applied
to the spiders and the experiment repeated.

After 48 hours

of hunger stress, the mature specimens were found hunting

121
in light levels up to 12 foot candles.

Again the immatures

were found hunting in slightly higher levels.

There is no

apparent reason except that they have not yet learned that
higher light levels may lead to higher predation levels.
The differences between the sexes of the mature specimens
is also difficult to explain.

Mature males were consist­

ently the animals found in the lowest light levels.

Fe­

males were always found in slightly higher levels# with
the immature forms found hunting in the highest light
levels.

This relationship was first observed during this

set of investigations and was noticed to be true for many
of the subsequent investigations involving adult and im­
mature animals.
When the animals were considered within buildings
the ability to obtain moisture became a question that needed
answering.

The question asked was whether or not the ani­

mals would be able to maintain themselves on a diet of
prey organisms with no water.

And if so# how long b e ­

tween feedings would the animals be able to stay active
and healthy.

The results of this study,

significant statistically as was hoped,

though not as
have shown that

there is a relationship between survival of the animals
and the frequency of feeding.

Because there was no wa t e r

introduced at any time, the only source of moisture was
that obtained from the food.

Two pilot studies were run

122
Initially to determine the length of time needed for the
spiders to die strictly from the effects of starvation,
and whether or not the animals would be able to survive
on a diet of dried prey.

The first study indicated that

the animals were unable to survive longer than 10 days
when all sources of food were withheld.

This held for

all three groups of animals, mature males,
immatures alike.

As the animals will only attack living

prey, as stated in Kaston
berlain

females and

(1933), Dondale

(1948), Gertsch

(1949) , Cham­

(1961), they were shown not to

be able to survive for any length of time on dry or
freshly killed prey with low moisture content.
By deduction then, if the only moisture present
was found in the prey animals,

then the prey animals must

contain adequate amounts of moisture to support the ani­
mals.

Peck and Whitcomb

(1970)

state that C. inclusum

was shown to prefer prey forms that were generally large,
slow moving and had high moisture content ratios to body
weight.

This date confirms my findings,

and so the animals

can be shown to acquire much of their moisture requirements
for the prey they eat and not necessarily from outside
sources.
Having poor eyesight and thus a small prey contact
distance, coupled with a moisture requirement of three to
five days, the hunting strategy would have to be a success­
ful one for the animals to survive.

The search patterns

F
123
were tested and found to be random in manner for both the
matures and the immatures.

The degree of randomness changed

from one sex to another and from one stress level to another.
This difference in significance level,

though slight, was

enough to indicate that the animals were effected in their
search patterns by hunger and the sex and degree of ma t u r ­
ity exhibited.
When the animals were considered as wandering for­
agers,

the degree of residency in any given area would be

dependent on the nearness of potential prey to the resting
cell and whether the resting cells were of real importance
in the hunting strategy of the spider.

The results of

the first two studies regarding return to previously con­
structed resting cells indicated that the resting cells
were reoccupied as many as two to three nights in succes­
sion.

The cells were not occupied for periods longer than

eight days.

When the search areas were not greater than

4.6 square feet in area,

the return rates were above 80%.

When the search area increased to near 8 square feet, the
return rates declined to an average of 75%, falling off to
near 60% when the search area exceeded 216 square feet.
Above 216 square feet the return rates would be expected
to continue to drop when related to prey densitiy.
When the effects of hunger stress were applied to
the animals, the return rates did not change significantly

124
until 72 hours of stress.

The greatest numbers of spiders

not returning to the previously constructed resting cell
was w h en the animals were stressed for 72 hours and the
search area was 216 square feet.

These results conclude

that the resting cell was used repeatedly when the search
area was small and prey capture was successful.
search area increased in size,

As the

the time to capture success

decreased and so did the return rate.

The resting cells

are therefore used repeatedly in high prey densities and
abandoned in areas of low prey densities.
Prey size selection was proven to be a character­
istic that could be altered through the effects of hunger.
When the spiders were in a satiated condition,

they exhib­

ited definite preferences for specific sizes of prey.
These preferences also were shown to vary from one sex to
another and from mature to immature animals.

The effects

of hunger stress were also exhibited from one group to
another.

From the hunger studies,

it can be stated that

the mature males attack a more diverse prey size range
than the females and the immatures.

The females are the

most severely affected by hunger stress in that they can
be influenced to take more diverse prey sizes based on the
degree of hunger applied.

The immature forms on the other

hand are relatively static in their response to hunger
stress.

Hunger stress was shown to lower the barriers of

both mature and immature specimens.

125
Prey size can be related to hunger and the sex and
maturity of the animals considered.

From this point of

view, prey size selection is a variable that is constantly
changing with the hunger state of the spider and the m a t u r ­
ity level of the spiders.
C. inclusum was shown to be worthy of the name
wandering or vagabond spider.

The distances traveled

were large for both mature and immature forms and con­
sistent from one search period to another.

The distances

traveled varied from one animal to another but were consist­
ent enough within the sex or maturity level that ranges
could be predicted when the sex and hunger levels were
known.
The relationship between sex, hunger level and d i s ­
tances traveled was direct,

linear and negative.

The more

the spiders were stressed by hunger the shorter the d i s ­
tances traveled.

Males were shown to travel further than

females and immature forms traveled the shortest distance
of all.

The opposite was found to be true of satiated

animals.
Under satiated conditions,
endurance levels remained high.

the energy levels and

The distances were near

the m a ximum for the sex and maturity level of the particu­
lar animal.

This assumption was less reliable when the

immature forms were considered.

The immatures were shown

to be less predictable in their responses to stress.

126
The predator-prey studies established the fact that
the successful capture of prey by C. inclusum was related
in a direct manner to prey density.

Because of the h u n t ­

ing patterns of the spider, the density and placement of
the prey should have little effect on capture success.
This is so due to the short contact distance of the spider.
When the short contact distance is coupled with the random
search pattern, each prey has an equal chance of being en­
countered,

assuming random spacing and placement.

The change in time to capture one prey in varying
prey densities was shown to be a straight line relationship
when there was one predator per search area.

The straight

line relationship held for medium to high densities but
when very low densities were encountered,

the time to

capture varied from five hours to more than one 10 hour
hunting period.
Holling
tors.

(1959)

These results differ from these given by
in his disc equation for invertebrate preda­

His equation gives a type 2 response curve, which

is a negatively increasing slope to a plateau.

One ex ­

planation for this difference is that the biology of the
spider affects the predatory behavior.
The spider,

though an active predator, does not

behave in the same manner as those reported by Haynes and
Sisojevic

(1966) , Turnbull

(1966), Dondale

(1970) .

C.

inclusum does not continue to attack and kill prey after
the initial prey has been captured.

After the capture,

127
the prey is eaten and then the search is continued until
the next contact is made, or the searching period is in­
terrupted by daylight or satiation.
The same relationship between capture time and prey
density held constant even w h e n the number of predators
was increased.

The correlation coefficient, however, d e ­

creased in value,

indicating that the relationship was

not as definite.

The increase from one predator to two

altered the equation for the relationship between the cap­
ture time and prey density such that the search time was
reduced.

In changing the predator density to four preda­

tors, the changes in the relationship evidenced by the
change in the equation, indicated an even stronger effect
of one predator on another by a more reduced search time.
Because no cannabalism was seen or the evidence of it d e ­
tected, the changes in the response equations can be con­
sidered to be the effect of the positive interaction
between the spiders.
In summary,

the results of this study indicate that

C. inclusum has a range including both the upper and lower
p eninsula of Michigan.

There is evidence that there may

be as many as two generations per year when considered
w i thin dwellings in Michigan.

The mature females usually

outnumber the mature males, and the immatures.

There were

two periods during the year when the populations within

128
dwellings exhibit peak densities.
April and October.

These two periods were

The effect of the spiders on resident

prey populations has been shown to be related directly to
the density of the spiders.

This is because the spiders

do not kill and eat large numbers of prey but kill and eat
only that amount which satiates them in areas of high prey
density or those prey animals that can be captured in one
hunting p e r i o d , if satiation is not reached.
W h en the prey density is low, the number of new
resting cells constructed will increase to one per hunt­
ing period.

After spending the daylight hours in the cell,

the spider begins its search and constructs another cell
the following morning.

In areas of high prey density,

the

resting cell may be used again the following day, depend­
ing on h o w far the animals have to wander from the cell
in search of prey.
The effects on the human population were shown to
be slight except for two short periods during the year when
the potential for harmful interaction is reased.

Bites,

when they occurred were few in number and were the cause
of only short term ill effects.
C. inclusum can be considered as a potential source
of biological control only on a limited bases because of
the basic biology of the a n i m a l .

The spider can there­

fore be considered as a resident species which has limited
effect on either prey organisms or the human inhabitants.

APPENDICES

A PPENDIX A
Introductory Letter and Data Sheet

130

131

COOPERATIVE
M ICHIGAN

STATE

EXTENSION
UNIVERSITY

SERVICE
•

CAST

LANSING

•

M ICH IGAN

Entomology
AND

U .S .

DEPARTMENT

February 23,

Of

AGRICULTURE

COOPERATING

Natural Science Building

1972

Dear County Extension Director:
You are already aware of my responsibilities as Survey Entomologist,
because it Includes the preparation of the "Insect Alerts" newsletter which
enters your mailbox each week from April to September.
You may not know,
however, of my Interest in spiders and my extension responsibilities for
Spiders occurring in dwellings.
Many county extension staff members have asked for literature that would
allow them to readily identify a majority of the spider specimens submitted
to their offices.
Public health officials, pest control operators, medical
doctors and others also have need for such literature.
I plan to produce
an extension bulletin that will serve this need among extension staff and
the other professional groups above.
First, however, I need more reliable information on the kinds of spiders
that occur in Michigan dwellings, their relative abundance, and association
of suspected spider bite cases with the creature that actually caused the
bite.
To gather some of this information I would like to conduct an extensive
one-year survey of spiders In dwellings throughout the state, and I invite
your cooperation In this survey.
You arc, of course, under no obligation to participate.
However, if you
feel that there Is a need for an extension bulletin on spiders, your contri­
bution would help make it a more accurate and complete bulletin.
If you or another staff member In your county office is willing to
cooperate, I would like you to save all of the spider specimens that you
receive during a one-year period (April I, 1972-March 31, 1973). t w t 11
provide you with a set of pre-numbercd, alcohol-filled vials and pre­
numbered forms on which to record the necessary information.
A copy of
the form is enclosed, and you can see that it is very brief and simple to
complete.
I will also provide you with a mailing container in which to
periodically ship me a group of vials.
In addition, I would like to be
notified each rime a suspected spider bi te is reported.
I wi11 attempt to
personally follow up each one of these'reports.
If you are willing to participate in this s u r v e y , please reply by
March 15 with the enclosed card.
I will then ship you a set of vials and
forms before April 1. Thank you for any attention which you may give to
my request.
Sincerely

Richard J. Sauer
Extension Entomology Specialist
and Survey Entomologist

132
SPIOER INFORMATION SHEET
R. J. Sauer
Dept, of Entomology
HSU

Spider N o .:
(Hatch this no. with no. In vial)
County:____________________________
D

Collected by:

Spider was found:

a

t

e

Inside of a bu 11d Ing

:

__________________

_

Outside of a building_____________ _________
(if you check outside plo'su make som.- notes on h-»bif>t
«.;ch .is host plnnt or substrvt. undt r "additional notes
b: low) .

Check one blank In each of the following nine categories on which you may have
Information:
1.

AREA:

Urban
Suburban
flu ra 1

2.

STATUS OF 9UUDII.G.

_________ In Use
________ Abandoned

3.

CONO IT ION:

________ Heated
________ Unheated

k.

CONSTRUCTION:

SIngle story with basement
________ Single story without basement
Hu 111 story with base'-e^t
Hu 11 istory without bnscmcnt

5.

EXTERIOR:

________ Brick
________ Wood
_ _ _ _ _ _ Aluminum nr Vinyl Siding
O ther (Specify)

6.

USE:
Fes Iliert ial

Commercial

_Single-fami Iy dwelling
HijI 11-fami ly dwelling

Form

Factory (Manufact.)
Retail ;non-food) or Business
[Retail food (grocery store)
Food serving (restaurant)
Food processing (dairy,
cor^crrtal bakery, etc.)

Bn r n

_________S* lo
__ 1ned
________ Other

(specify)

7.

SPIOEfl LOCATION IN BUILDING:

8.

PRESENCE OF WEB:

Found in web
W ebbing evident nearby
No web

9-

SPIDER BITE7

Bite reported
No bite reported

Additional notes

(optional):

_________Basement
Bathroom
________ Attic
________ C loset
______Ki t c h m
________ Other isrec.ify)

APPENDIX B
Number of Spiders Sent by County Agents

133

TABLE APPENDIX B.l.— Spiders Turned in by County Agents.

County

Spiders

01
03
07
08
09
10
11
15
17
20
24
25
27
28
30
31
34

13
14
21
26
10
15
3
41
7
15
1
3
6
16
18
13
1

County

Iosco
Kalamazoo
Kalkaska
Lake
Lapeer
Leelanau
Lenawee
Livingston
Luce
Macomb
Manistee
Mason
Mecosta
Menominee
Missaukee
Monroe
Montcalm

Code
No.
35
39
40
43
44
45
46
47
48
50
51
53
54
55
57
58
59

Spiders

10
33
14
6
3
18
8
7
19
312
8
7
3
77
5
63
6

County

Code
No.

Spiders

Montmorency
Muskegon
Oakland
Osceola
Oscoda
Ottawa
Presque Isle
Roscommon
Saginaw
St. Joseph
Sanilac
Tuscola
Van Buren
Washtenaw
Wayne
Wexford

60
61
63
67
68
70
71
72
73
75
76
79
80
81
82
83

12
9
22
3
9
5
13
22
12
14
10
6
21
4
111
13

TOTAL

53

1147

134

Alcona
Allegan
Baraga
Barry
Bay
Benzie
Berrien
Charlevoix
Chippewa
Crawford
Emmet
Genesee
Gogebic
Gr. Traverse
Hillsdale
Houghton
Ionia

Code
No.

APPENDIX C
Statistics for Size Class Study, Distance
Study and Predator Prey Study

135

136
TABLE APPENDIX C.l. — Size Class study •
cf
Sm.
Md.

9

Iran.

X

8
7
5
6.6

8
6
4
6.0

8.3
7.0
5.0

X

9
8
6
7.7

Sm.
Md.
L?.
X

9
8
8
8.3

8
7
6
7.0

8
7
5
6.6

8.3
7.3
6.3

Sm.
Md.
Lg.
X

9
8
8
8.3

8
9
8
8.3

7
6
4
5.7

8.0
7.7
6.9

Significance Levels

Aov.

.24 Hour
Starvation

48 Hour
Starvation

72 Hour
Starvation

df

M.S.

F
9.48*
37.95***

Col.
Row
Error

2
2
4

4.222
16.889
0.445

Total

8

21.556

Col.
Row
Error

2
2
4

4.666
5.999
1.335

Total

8

12.000

Col.
Row
Error

2
2
4

14.222
2.889
3.112

Total

8

20.223

3.39
4.49

4.56
<1.0

N.S.
/

P>0.1
N.S.

0.10 ✓
0“lt>5 *
0.01 **
0.005 ***

TABLE APPENDIX C.2.— Distance Study, AOV Table.
Factor

df

M.S.

A
B
C
AB
AC
BC
ABC
J

2
5
1
10

2,415,367
4,502,551
57,553
456,381
191,219
177,826
2,981,545
201.866

2

5
10
144

Significance Levels

F
11.97
22.3
<1
2.26
<1.
<1.
14.7

Factors

Cf

****
****

A = Sexes;

N.S.

B = Starvation Levels

N.S.
N.S.

C = Before + After
Capture of Food

*

****

.05 *
.01 * *
.005 ***
.001 * * * *
N.S. Non Significant

, QT

, Inun

137
TABLE APPENDIX C.3.— Analysis of Variance for Universe Size,
Prey Density and Predator Density
Study.
Factor

df

SS

MS

F

Significance

A

2

77.389

38.695

19

***

B

4

107.386

26.847

13.4

***

C

2

228.881

114.441

57

•*■***

AB

8

24.140

3.018

1.41

AC

4

210.334

52.584

24.51

****

BC

8

104.816

13.102

61.08

****

ABC

16

407.166

25.448

11.86

****

180

386.850

2.145

J

Factor A = Universe Size
Factor B = Prey Density
Factor C = Predator Density
Significance Levels

.05 = *
.01 = * *
.005 = ***
.001 = * * * *

P<.25

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i