THE EXTERNAL ANATOMY OF
MELANOTUS COMMUNIS. GYLL

Thais for the Degree of M. S.

MiCHlGAN STATE COLLEGE

George Edward Coppel
1943 ,

Thlslstoeerdfgthat'the

thesis entitled
THE EXTERNAL ANATOMY OF

I-EMJ‘IOTUS COMMUNIS, GYLL

presented by

George Edward Coppel

he. been accepted towards taunt—m Z
of the requirement- for )

Master officirenceaégm in Entomolbgy

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Date MErCh 22 1948

 

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THE EXTERNAL ANATOHY'OF MELANOTUS COMMUNIS, GYLL.

By

GEORGE EDWARD EQPPEL

A THESIS

Submitted to the School of Graduate Studies of Michigan
State College of Agriculture and Applied Science
in partial fulfillment of the requirements

for the degree of

MASTER OF SCIENCE

Department of Entomology

19u8

MTHESIS'

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ACKNOWLEDGMENTS

The writer wishes to express his sincere thanks
to Professor Ray Eutson, Head, Department of Entomology,
Michigan State College, for his willing guidance and en-
couragement, and also to Professor E. I. MacDaniels, for
the interest shown and many helpful suggestions made.

Appreciation is also expressed to Mr. H. G.
Crawford, Head, Division of Entomology, Canada, and to
Mr. H. L. Seamans, Chief, Field Crop Insect Investiga-
tions, Division of Entomology, Canada, for arranging leave
of absence to make this thesis possible.

To Dr. H. Dietrich, Entomology Department, Cor-
nell University, for his verification of specific ident-
ification, and to R. H. Engstrom, for inking the final
drawings, the author expresses.his thanks.

TABLE OF CONTENTS

Page
IntrOduCtion O O O 0 O O O O O O O O O O O O O O O O O O O O O 0 O O ...... O O 0 O O O O O 1
synonomy. O O O O O O O O O O O O O I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O 0

Life History of Melanotus communis, Gyll..............

 

2

3
-Geographical Distribution in North America............ 5
Material and Methods.................................. 6
General Description of Adult.......................... 11
Detailed Description of Adult......................... 13
Literature Cited...................................... 33

Key to P1ates...........................P1ates No. l to 8

INTRODUCTION

Considerable effort has been expended on the
bionomics of many Species of Elateridae that are serious'
economic pests in our agricultural setup. Most of the
work has been done on the larval (wireworm) stage which
causes great losses in our crops.

The Elaterid genus, Melanotus, is quite common
throughout the eastern United States, and eastern Canada,
as a pest of corn. As considerable confusion exists
in this group, especially in the Melanotus communis,
Gyll. and Melanotus fissilis, Say, species, it was decided
to work out the external anatomy of the adult Elaterid,

Melanotus communis, Gy11., as a contribution of a type

 

description of an economic species of wireworm.

-2-
SYIONOHY

The synonomy of Melanotus communis, Gyll. is
as follows:
1. Helanotus cinereus, Heber.
2. Helanotus communis, Gyll.
3. Melanotus simplex, Germ.
4. Helanotus spadix, Er.
J. L. Weber first described thfb species as
Helanotus cinereus in 1801. In 1817, L. Gyllenhal re-
described it as Helanotus communis. E. P. Germar, in
182“, named it lelanotus simplex, and v. F. Erichson,
in 18#2, called it Helanotus spadix. (11).
Dr. H. Dietrich (2) later broke this down into:
1. Helanotus communis, Gyll.
2. Helanotus communis, Var. “A."
3. Helanotus communis, var. ”B.”
The basis of Dietrich's work was based on gen-

italic variation.

-3-
LIFE HISTORY OF NELANOTUS COHEUNIS, GYLL.

The life history for this genus is very incom-
plete due to the long time spent in the larval stage'
underground, and the attending difficulties of rearing
such an insect. It is generally believed to have a life
cycle of three or four years.

The duration of the larval period of Helanotus
communis, Gyll. is said by Comstock and Slingerland (1891,
page 263) (4), to be at least three years. This conclu-
sion is based on the length of time between confinement
of larvae in soil cages and emergence of the beetles.

Blatchley (1) says that the larval stage ex-
tends over three or four years, and while Hawkins (4)
says that under laboratory conditions it is at least
three years, he generalizes for the whole Genus Melanotus,
and does not commit himself on the species 5. communis,
Gyll.

Fenton (3) states that g. communis, Gyll. has
a life cycle of at least six years, and the following is
abstracted from.his paper.

The adults emerge from their spheres of hiber-
nation, (usually under loose bark, or in cracks and crev-
ices of rotten logs and stumps) in May or early June, and
are quite active in flight. During the adult stage they
feed mainly on pollen.

The eggs are laid mainly in June, and possibly
as late as July. They are placed in the soil by the female

-u-

at a depth of one or two inches. Eggs are laid singly,
and are spherical and pearly white.

The eggs hatch in July into small, pale yellow-
ish larvae. The growth is slow and one larval moult
takes place, with the larvae passing the first winter in
the second instar.

The second, third, fourth and fifth years are
spent in the larval stage, with one or two moults each
year. During this period they do the most damage, espe-
cially to young corn, attacking the kernels after they
swell, and eating them.comp1etely out. They also attack
other young plants after germination, eating away the
roots, causing the plants to wither and die.

Pupation takes place in late July or August of
the sixth year, after a moult followed by a period of
activity, during which time they construct an oval cell
in the soil, become torpid, and finally moult into the
pupal stage. The pupal stage lasts from seven to 39
days, with a mean of 18.14 days for 42 records.

Emergence, therefore, takes place in late
August and early September. The winter is spent hiber-
nating above the ground, under bark, cracks or crevices
of logs and stumps, where they are sheltered. They may
hibernate singly, in groups of two or three, or occasion-

ally in groups of as many as fifteen.

-5-
GEOGRAPHICAL DISTRIBUTION IN NORTH AMERICA

15. communis, Gyll. is quite common in eastern
Canada and eastern United States, to Nebraska, and south

to Louisiana and Florida (1).

-5-
MATERIAL AND muons

(a) Collection and preservation of material.

Adults were collected mainly on the campus of
Michigan State College in the demonstration woodlot on
the south shore of the Red Cedar River, during the fall
term of l9n6.

They were found singly or in groups of two or
three, or up to as many as fifteen in a group. The fa-
voured places for hibernation were under the loose bark
of rotten logs and stumps, or in cracks and crevices in
the wood itself. There was no indication that the adults
actually burrowed into the log, but seemingly forced
their way into sheltered spots.

Adults collected after snowfall and freezing
weather, became active in a matter of a few minutes while
lying on the palm of the hand. Some of the specimens
collected were placed in small cages with damp moss, bark
and rotten wood, and lived for over three months. They
were quite active when in a darkened area, but burrowed
under the debris when lights were switched on.

The remainder, and bulk of the specimens were
killed in cyanide bottles, and then stored in sixty per
cent alcohol. These adults were the most satisfactory
for dissection and study, as the tissues did not become

dessicated.

-7-

(b) Techniques for extrusion of genitalia.

As one of the main features of identification
of this species is based on male genital characteristics
(2), several methods for extruding the aedeagus and pro-
trusible abdominal segments were tried.

Barber's solution (16) and Dietrich's solution
(2) for relaxing and work on genitalia were used in the
early stages of this study, and were made up as follows:

Barber's solution

Ethyl alcohol..............265 parts.

Distilled water............2#5 parts.

Ethyl acetate.............. 95 parts.

Benzol..................... 35 parts.

Dietrich's solution

Ethyl alcohol..............280 cc.

Distilled water............230 cc.

Ethyl acetate.............. 95 cc.

Benzol..................... 35 cc.

The benzol separated out on top of the solu-
tions, due to its lack of miscibility with the water in
the solutions. Agitation was tried with both solutions,
but after standing a short time, the benzol separated
out again. .

To get around this difficulty, samples were
made up, and a small amount of sodium laurel sulfate
(Dreft) added to each formula. These solutions were agi-
tated, and the resulting emulsion allowed to settle. This
produced a milky fluid, which, after standing, ”creamed"

-8-

somewhat, but still retained its milkiness, indicating
some benzol dispersion, and the probability of some action
on the tissues immersed, by the benzol in the formula.
Specimens were placed into these solutions and
removed forty-four hours later. The genitalia were ex-
truded approximately three-quarters of their length, and
became fully extended when pressure was applied to the
abdomen. This method was used in the earliest stages
for extruding genitalia, but later work produced a method
that cut down on the time necessary, and involved less

handling.

(c) Preferred technique for extrusion of genitalia.

Whole specimens were gently boiled in ten per
cent potassium hydroxide for thirty minutes, rinsed in
distilled water, and then placed into three per cent
hydrogen peroxide for bleaching. After an interval of
about thirty minutes, examination of the material shows
that bubbles form.in and around the specimens, and that
fine genitalia are starting to voluntarily extrude. After
an hour in the solution, examination will show that in
most cases the genitalia, both male and female, are fully
extruded, and that bleaching has also been affected. Sev-
eral slides were made up from this material to supplement
those previously made.

Further tests were carried out using the above
method, with both dried and preserved material. This
method did not work with dried material, but was very

-9...

effective with all material that had been freshly killed
and preserved. This method should be of considerable
aid to systematic entomologists, as the whole procedure
of clearing, bleaching and extrusion, as well as less
manipulation, can be affected in approximately one and

one-half hours.

(d) Technique for clearing and bleaching.

Clearing was done by using ten per cent potas-
sium.hydroxide and heating gently for about thirty minutes.
The specimens were then rinsed several times in distilled
water, and then dissected under water. Due to the heavy
sclerotization and dark colour, most of the material for
slide preparation had to be bleached, and the dissected
material was placed into three per cent hydrogen peroxide
until the desired degree of colour was reached, then
removed to and washed in water.

Slides of the mesa and metathorax, as well as
those of the dorsal abdominal area, were not cleared, as
clearing removed the underlying fat bodies. The result-
ing thin membranous areas lost their identity without
the background of fats to throw the segmentation and scler-
otization into relief. ‘

(e) Technique for slide preparation.
Slides were prepared by running the dissections
through the various strengths of alcohol as normally re-

commended (9). Xylol was used for Balsam.mounts, but most

-10-

of the slides were mounted directly from absolute alcohol

into Diaphane.

(f) Technique used in study and drawing.

A squared grid in the eyepiece of the compound
microscope was used in connection with graph paper to
draw the various structures and appendages to proportion,
and the scale was varied, depending on the size of the
appendage or area to be depicted. A #H pencil was used
for all drawings. when completed and checked, the draw-
ings were traced onto Strathmore Board, and inked in with
India Ink.

-11-
GENERAL DESCRIPTION OF ADULT

The adult of Melanotus communis, Gyll. is dark
brown to reddish brown in colour, and clothed with a
fine, dense pubescence. The third antennal segment is
somewhat shorter than the fourth, and the fourth antennal
segment of the male has short erect bristles on its in-
’ferior margin. The antennae are serrate and eleven Jointed.
The clypeus is margined in front.

The pronotum is never wider than the base of
the elytra, and is broader than long. The prosternum.is
lobed in front, the sutures double, concave on the outer
side, and the prosternum.prolonged into a prosternal spine
posteriorly.

The mesothoracic legs have a small trochantin,
and the coxal plates of the metathoracic legs are grad-
ually dilated inwards to form a protective plate over the
femora when at rest. The tarsal claws have distinct
comb-like teeth or pectinations. The elyta have nine
striae, which are coarsely and irregularly punctured,
with the intervals punctate.

* The male genitalia (Plate 7) are the best recog-
nition marks for this species (2). The length of the
adult varies from.ll.5-l4 mm. with the female usually
slightly larger than the male.

The adults of this species, in common with all
members of the family Elateridae, possess the power of
springing into the air when placed on their backs. This

-12-

springing motion is possible because of certain structural
characteristics. The prothorax and the mesothorax are
loosely Joined, the base of the prothorax and the base

of the elytra slope downward toward each other, and the
prosternal spine projects posteriorly to fit into the
mesosternal cavity. Preparatory to springing into the
air, the prothorax and head are bent back, thus bringing
the prosternal spine slightly above the mesosternal cav-
ity, and at the same time raising the base of the elytra
slightly above the surface on which the inverted beetle

is resting. By suddenly relaxing the muscles, the pro—
sternal spine descends forcefully into the mesosternal
cavity, causing the base of the elytra to strike violently
against the supporting surface, and by their elasticity
the whole body is propelled upward (1).

-13-
DETAILED DESCRIPTION OF ADULT

Head and mouthparts: Plate 1, Figs. 1, 2, 3, 4, 5, 6.
Plate 2, Figs. 1, 2, 3, 4. Plate 8, Figs. 3, 4.

The head is oval in outline from above, with
the eyes protruding laterally. The superior margin or
postoccipital suture (Fee) is regularly curved on its
median portion, with the sides oblique and nearly straight
to the lateral margins. (Plate 1, Fig. 2). The infer-
ior margin is shallowly concave between the gular sutures
ventrally (Plate 2, Fig. l). A heavy carina (Plate 2,
Fig. l) arises on the anterior end of the gena (Ge) and
extends posteriorly and upwards around the margin of the
eye (E) and gradually fades out in the line on the occi-
put (0c) parallel to the margin of the eye. (Plate 1, Fig.
2). The occiput is finely and closely punctate. Anterior-
ly the gena (Ge) is narrowed between the base of the
maxilla and the eye, to the basal margin of the mandible
(Md). The interior margin of the gena is bounded by the
gular suture (Gs) and exteriorly by the margin of the
eye (Plate 2, Fig. l).

The head is retracted about halfway into the
prothorax, and the fronto-buccal region inclines forward
and downward (Plate 1, Fig. 3). Viewed from the front,
the frons (Fr) is strongly transverse, bounded laterally
by the eyes and anteriorly by the free or frontal margin
(Fm) of the frons, which is broadly rounded. The frons
(Fr) is feebly convex, almost flat. The fronto-clypeal

-1u-

region (Clp) is bounded laterally by the eyes, basally
by the frontal suture, and distally by the base of the
labrum (Em) and the insertion of the mandibles (Md).
'This region bears the antennal sclerites (Ants) and the
parantennal foveae (PAnt), and is transverse. The anten-
nal sclerites are located near the lateral margins of
the fronto-clypeal region, above the middle, and bear
the insertion of the antennae. Between the antennal
sclerites are a pair of parantennal foveae, which are
shallowly impressed in a vertical plane, with the area
between them quadrilateral in shape. The labrum (Lm)

is free, transverse, broadly rounded on its inferior mar-
gin and sides, with the superior margin straight. It

is heavily sclerotized. On its inner surface is a mem-
branous epipharynx (Ephy) which is partially visible
below the inferior margin. The eyes are widely separated,
compound, large, nearly hemispherical and emarginate

from the lateral extremities of the occiput, posteriorly
and downwards to the anterior end of the genae ventrally
(Plate 1, Fig. 2, Plate 2, Fig. l). The mandibles are
robust externally, strongly curved, cleft near the apex,
rugosely punctate and ciliate at the basal external por-
tion. The left mandibular tip overlies the right man-
dibular tip, the right mandible being a bit more strongly
curved than the left. The prostheca (Prs) is broadly
rounded, pubescent along its free margin, and prominent
when the mandible is extended. The flexor muscle is

strongly developed and attached along the middle of the

-15-

basal margin. The retractor muscle is weak and used only
for opening the mandible. There are two condyles (anter-
ior and posterior) present for articulation. The mandibles
are relatively short, never extending far beyond the labrum
(Plate 1, Figs. 1, 4, 5).

Ventrally the gula (Cu) is clypsedral (17) in
outline, being strongly constricted behind its middle.
Anteriorly it is bounded by the transverse mental suture
(Hts), latero-anteriorly by the cardo (Cd) and the genae
(Ge). Posteriorly the margin is shallowly concave (Plate
2, Fig. l).

The labium consists of the sclerites lying
anterior to the gula, the first being the submentum.(Smt).
Its base is transverse and contiguous with the gula, and
separated from it by the mental suture (wts). The lateral
margins converge anteriorly, and the anterior margin is
sinuate. The submentum bears a pair of long, converging,
anteriorly directed hairs, their bases being Joined by a
concave, shallow fossa (Plate 2, Fig. 1).- Closely Joined
and anterior to the submentum, is the semi-membranous
mentum.(nt). Laterally it continues the anteriorly
convergent sides of the submentum, The posterior margin
of the mentum.is contiguous with that of the submentume
The anterior margin of the mentum is truncate, except
for a small sinuation rising between the bases of the
palpigers (Plg). Lying forward of the mentum is the
membranous ligula (Lig), which is broadly triangular,
and slit along its median line almost to its base. The

-15-

anterior margin of the ligula is fringed with a fine pub-
escence. Lying ventrally to the ligula and anteriorly
to the mentum are the labial palpi (LbPlp). The labial
palpus is three Jointed, the first Joint being broad and
short, the second Joint about twice as long as the first,
narrow at its basal end and expanding apically. The
third Joint is the largest of the three, securiform.and
curved at its base. The palpus has its origin in the
robust palpiger (Plg) which is about one and one-half
times as long as broad (Plate 2, Figs. 1, 3, 4).

The maxillae lie along the latero-ventral sides
of the head, are composed of variously segmented basal
areas, and carry four Jointed maxillary palpi. The cardo
(Cd) lies in an anterior depression of the gena (Ge),
and has a transverse anterior margin which is continuous
and on the same plane as the mental suture. The interior
lateral margin of the cardo is straight with a slight
sinuation at its posterior end, and the exterior latero-
posterior margin is weakly convex. Contiguous with the
anterior margin of the cardo is the base of the basis-
tipes (Est), which is straight on its inner lateral margin,
convergent anteriorly on its external lateral margin.
These two margins are Joined by an oblique anterior mar-
gin, which bears a small, oblique palpifer (Plf) that
acts as the basal point of articulation for the maxillary
palpus (NxPlp). The maxillary palpus is four Jointed,
the first Joint small and slightly longer than wide, the
second elongate, obconical, slightly longer and heavier

-17-

than the third. The third is also obconical and slightly
arcuate on the exterior margin. The fourth Joint is
slightly longer than the second, triangular, with its
exterior margin nearly straight and its interior margin
slightly arcuate. The stipes (St) lies between the basi-
stipes and the submentum, with a narrow basal end expand-
ing anteriorly. It bears the semi-membranous, blade-like
lacinia (Lc) on its interior lateral margin. The external
margin of the lacinia is thickly ciliate. Anteriorly

the basistipes bears the oval shaped galea (Gal), which
is also thickly ciliate on its apical margin (Plate 2,
Figs. 1, 2).

The antennae are serrate, eleven Jointed, with
the terminal Joint entire. The basal Joint is subcylin-
drical, arcuate and about two and one-half times as long
as the second, which is small and subglobular. The third
Joint is fully one and one-half times as long as the sec-
ond, and almost as long as the fourth. The fourth to
tenth segments are subtriangular and subequal in length.
The eleventh segment is elongate oval with the apex
rounded. The fourth to eleventh segments of the male
are characterized by a thick, erect pubescence on the
inferior margins, which is not present in the females
(Plate 8, Figs. 3, 4). The antennae arise near the eyes
and under the frontal margin, are widely separated, and

inserted in small antennal sclerites (Plate 1, Fig. 1).

-18..

Prothorax: Plate 3, Figures 1, 2, 3, 4, 5, 6.

 

The notum (Nt) of the prothorax (Fig. 2) is
roughly quadrilateral, with its anterior margin slightly
sinuate, and the anterior angles not produced. The lat-
eral margins are subparallel for their basal half, and
then converge gently to the anterior angles. Posteriorly,
the margin of the prothoracic notum is nearly truncate,
varied by slight sinuations, and deflexed. The puncta-
tion of the notum is variable, but is noticeably finer
and sparser on the disc than on the lateral margins. The
prothorax is wider than long, and the relative width is
greater in the female than in the male, but not wider
than the base of the elytra. There is a median slightly
impressed line on the basal half of the prothoracic notum.
Posterior angles (Pa) are prominent, produced posteriorly,
and bear two carinae, the inner of which is less well
defined and diverges inwardly. The posterior angles
embrace the base of the elytra. Medianly from each pos-
‘terior angle, at about one-quarter of the width of the
notum, are the short sulci (Sul) with their basal notches.

The sternum (St 1) of the prothorax (Fig. l, 4,
5, 6) is convex and longitudinal, with the sides subpar—
allel as far as the coxal cavities (Cc). Anteriorly it
is broadly rounded, slightly deflexed to form a prosternal
lobe (Ptl) with a finely raised free margin. On either
side, the sternum is bounded by externally concave, double,
sterno-pleural sutures, which are slightly widened and

excavate anteriorly. Posteriorly these sutures curve

-19-

outwards, and the inner one ends in a small pit near the
anterior end of the coxal cavity. The outer suture con-
tinues posteriorly, passing around the coxal cavity and
finally disappearing in the general direction of the pos-
terior angle as a vague sinuate line. Posteriorly the
sternum of the prothorax is sharply narrowed by the coxal
cavities to form the prosternal process or spine (Fee).
The prosternal spine is slightly concave between the coxal
cavities, with its lateral margins somewhat rolled. Along
the posterior third of the coxal cavities, the prosternal
spine becomes gently declivious, at the same time narrow-
ing more sharply on its ventral face than on its dorsal
face. The tip is slightly declivious, forming a blunt
apical point which slopes gently towards the mesothorax.
Between the sterno-pleural sutures and the
lateral margin of the notum.1ies the episternum (Epsl),
which is made up of the fused inflexed portions of the
tergum and pleurum. Anteriorly, the outline of the epi-
sternum is subovigal and for a short distance along the
middle its sides are nearly parallel. Its posterior
margin is oblique and widely sinuate. The episterstum
is nearly flat, except for a shallow excavation near the
posterior angle. The coxal cavities are fairly large,
circular in outline anteriorly, and open behind. The
sternum is irregularly punctate, heavily chitinized
and sparsely pubescent. The prothorax is loosely Joined
to the mesothorax. ‘Ventrally, the prothorax bears the

prothoracic legs.

-20-

Mesothorax: Plate 4, Figures 1, 3.

The only part of the notum of the mesothorax
visible externally is the elevated, suboval scutellum
(Scl), which rises medianly between the bases of the ely-
tra. The mesothorax is loosely connected with the pro—
thorax, and bears the elytra dorsally and the mesothoracic
legs ventrally. When the elytra are removed they expose
the prescutum.(Psc) which is roughly yoke shaped, trans-
verse, has a medianly reentrant anterior margin, and a
strongly depressed central area. Posteriorly it bears
the anterior notal wing processes (ANP). The scutellum
(Scl) is suboval and prominent, heavily chitinized, punc-
tate and pubescent. It subdivides the scutum (Sct),
which is small and closely fused to the scutellum (Fig. 3).
The scutum bears the posterior notal wing processes (PNP).

The sternum.(St 2) is roughly pelecoidal (l7),
and except for the mesosternal cavity (M80) and the pos-
terior intercoxal piece, is not very prominent. Anter-
iorly, the margin is double and interrupted by a prom-
inent median bifid knob, which marks the anterior end
of the mesosternal cavity (Fig. l). The lateral margins
slope away to meet the coxal cavities (Cc). The pos-
terior margin is defined by the coxal cavities, which
are separated by a tongue-like area that extends to the
narrowest point between the coxal cavities, where it forms
the transverse meso-metasternal suture. The mesosternal
cavity occupies about oneethird of the entire area of

the sclerite, and is roughly flask-shaped with its

-21-

posterior end pyramidal. It is narrow at its anterior
end, widens gently to about two-thirds of its length,
and then becomes posteriorly pyramidal. It is separated
from the coxal cavities by a narrow band of the meso-
sternum.

The episternum (Eps 2) is irregular in outline,
with its external angle bluntly rounded. Its interior
lateral margin is sinuate and oblique, and lies along
the lateral margin of the mesosternum, extending pos-
teriorly about two-thirds of the length of the latter.
The exterior margin is roughly convex, and has an oblique
marginal cleft below the exterior angle, into which the
inflexed margin of the elytron (El) fits when at rest.

It is a small sclerite.

The epimeron (Epm 2) is a small sclerite lying
beside the posterior lateral margin of the mesosternum
and beside the coxal cavity (Cc). The interior margin is
concave on its anterior half, with the posterior half
straight and extending to partially close the coxal cavity
with the trochantins (Tro). The posterior margin is con-
cave and contiguous with the sternum and episternum of
the metathorax. The exterior margin is sinuate and sul-
cate to receive the margin of the elytron.

Associated only with the mesothorax are the
trochantins (Tro) which are small, roughly quadrate scler-
ites, lying at the union of the posterior lateral margin
of the mesosternum, the posterior internal angle of the

mesa-epimeron, bounded on its interior margin by the coxal

-22-

cavity and posteriorly by the angular exterior proJec-
tion of the coxal cavity. The coxal cavities are sub-
spherical and rather large, with an outer angle along
the horizontal median plane. The sternal sclerites are

heavily chitinized and punctate.

Elztra: Plate 5, Figure l.
The elytra are strongly chitinized, clothed

with a fine pubescence, the disc feebly convex anteriorly
and distinctly convex posteriorly. ,They are borne on

the dorsal surface of the mesothorax, and meet in a
straight line on the meson when at rest. The anterior
margin is deeply emarginate on its interior margin to
receive the mesothoracic scutellum, and is transversely
rounded and sinuate. The base of the elytra are embraced
by the produced hind angles of the prothorax, and as the
bases of the prothorax and elytra are strongly deflexed
towards each other, there is a slight separation between
them, which is sufficient to permit the freedom of move-
ment necessary for the characteristic clicking and Jump-
ing.

The elytra are somewhat expanded in the humeral
region, and the humeral angle is strongly carinate. The
exterior lateral margins are subparallel for about two-
thirds of their length, and then gradually converge to
a rounded apex. Each elytron bears nine stria (Es),
which are coarsely and irregularly punctured, with the

intervals punctate. They are widely separated at the

-23-

basal end (before the humeral angle), and gradually con-

verge at the apical end of the elytron.

Metathorax: Plate 4, Figures 1, 3.

Dorsally the metathorax is covered by the elytra.
The scutellum (Scl) divides the roughly quadrate scutum
(Set) by a narrow median tongue that extends anteriorly
from an expanded, transverse basal scutellar area. The
median scutellar tongue expands laterally as it reaches
anteriorly. Each lateral division of the scutum is par-
tially divided by a transversely oblique suture, into
anterior and posterior areas. The anterior scutal area
bears the anterior notal wing process (ANP), and the pos-
terior scutal area bears the posterior notal wing process
(PNP). The postnotum (PN) is strongly transverse, straight
on its anterior median margin, convex on its posterior
median margin, partially divided by a broken transverse
suture, and gradually fades laterally into the area of
wing articulation and sclerotization (Fig. 3). The pos-
terior margin of the postnotum is closely connected and
contiguous with the anterior margin of the first abdom-
inal tergite (T l). Anteriorly the notum is closely con-
nected to the mesothorax. The entire notum of the meta-
thorax is semi-membranous.

The sternum (St 3) is convex and subquadrate,
heavily sclerotized, coarsely and irregularly punctate
(Fig. 1). Its anterior margin is roundly emarginated by
the coxal cavities (Cc), the lateral margins straight and

-24-

slightly divergent posteriorly. The posterior margin is
sinuate and forms an anticoxal piece along its median
line, partially subdividing the anterior-interior margins
of the metathoracic coxal plates (Cx). The metathoracic
coxae (Cx) are contiguous with the sternum along the
entire length of its posterior margin, except for the
separation made by the anticoxal piece. The sternum
bears a median longitudinally impressed line known as

the metasternal suture (NBS), which extends anteriorly
about two-thirds the length of the sternite.

The episternum (Eps 3) is elongate, slightly
wider at its anterior end, and divided into two parts.
The visible part is elongate, narrow, heavily sclerotized
and punctate, while the area enclosed by the elytron is
membranous, elongate, and wider at its anterior end.

The epimeron (Epm 3) lies in a lateral and dorsal plane
along the latero-dorsal margin of the episternum, and is
not visible ventrally. The dorsal plane is semi-membran-
ous and sub-triangular in shape. It narrows anteriorly
and extends towards the axillary wing process (A 2)

(Fig. 3), and posteriorly to the anterior margin of the
first abdominal tergite. It is widest opposite the pos-
terior postnatal suture. The lateral area is membranous,
narrow and elongate. The metathorax bears the membran-

ous wings dorsally and the metathoracic legs ventrally.

-25-

‘Einggz Plate 5, Figure 2.

The functional wings are of the Cantharoidean
type as characterized by Gahan (17). When at rest, with
the elytra covering them, they are infolded at the apex
and along the inferior margin. The apical infolding is
marked by areas of slightly thickened membrane (see Figure
2), but there is no structural evidence of folding along
the inferior margin.

. The second anal vein (A 2) crosses and inter-
rupts the first anal vein (A 1). The anterior branch of
the media (M l) and the posterior branch of the radius
(R 2) are hooked, giving them.the appearance of being
recurrent branches of their respective veins. A short
radial spur (Rs) is attached to the second radial vein
(R 2).

19355: Plate 6, Figures 1, 2, 3, 4, 5, 6.

The prothoracic legs are attached to the pro-
thoracic coxal cavities (Co) by prominent, subglobular
coxae (Cx), into which the small triangular trochanters
(Tr) are articulated. The trochanters are connected to
the femora (Fm), which are short, stout, straight on the
inferior margin, convex on the superior margin, and hol-
lowed slightly on the inferior face to receive the tibia
when at rest. The tibia (Tb) are slender, elongate-
cylindrical, slightly elbowed at the anterior articula-
tion with the femora, slightly greater in diameter pos-
teriorly, and bearing a pair of tibial spurs (Ts) at

-26-

their posterior end. The tarsi (Tar) are five in number;
all are slender, being progressively reduced in length
from the first to fourth tarsal Joint. The fifth tarsal
Joint (Tar 5) is slender and equal in length to the first
tarsal Joint. (Fig. 3). The fifth tarsal Joint bears

a pair of chitinous divergent claws (To) which are pec-
tinate (Pt). Considerable variation exists in the number
and character of the pectinations (Fig. 4, 5), not only
in the species or individual, but even in the two claws
of the same tarsus (17).

The mesothoracic legs are attached by rounded,
subspherical, but not prominently protruding coxae, which
are hollowed slightly externally, to accommodate the
trochanters and part of the femora when at rest. The
trochanters are relatively small, triangular, and closely
united with the femora. The femora, tibia and.tarsi
follow the same general description as that of the pro-
thoracic legs (Fig. 2), but they are generally larger in
proportion.

The metathoracic legs are closely attached to
the metasternum along the entire length of its posterior
margin, except for a separation along its median line,
by the hind coxae. These coxae are flat, strongly trans-
verse, gradually narrowed, and separated along their
inner margins by the anticoxal pieces of the metasternum
and the first abdominal sternite. The posterior margin
of the coxa is gradually dilated inward, and sulcate or

strongly excavate for the reception of the femora in

-27-

repose. The small, roughly rhomboidal trochanters lie
between the coxae and the femora, being loosely articu-
late with both. The femora are subparallel on their
superior and inferior margins. Tibia and tarsi follow

the same general description as that used for the pro-
thoracic legs, except that they are relatively larger
(Fig. 1). All three pairs of legs are heavily sclerotized

and punctate.

Abdomen: Plate 4, Figures 2, 4.

The abdomen is elongate triangular, with sides
gently arcuate, especially on the apical third. It is
composed dorsally of seven tergites (T), and ventrally
of five sternites (S).

The tergites (T) are visible when the elytra
are removed or raised. The first six are membranous
and closely connected with the tergopleural membrane.

The median length of the first tergite (T l)
is slightly less than that of the second tergite (T 2),
and both are shorter than each of the remaining five.

The seventh tergite (T 7) is similar in both
sexes. It is narrower, longer, moderately sclerotized
and flexible as compared to the preceding segments. The
outline is roughly subtriangular, fimbriate posteriorly,
and broadly rounded medianly. It is emarginate on either
side before the apex, with a longitudinal impression be-
ginning at the emargination and continuing more or less

parallel with the lateral margin nearly to the base.

-28-

The tergum is parallelled on either side by a
lateral ridge (Lr) extending from the second to the sev-
enth tergite, and is formed by the pleurite. A narrow
channel into which the elytron fits when at rest, sepa-
rates it from the sternites.

Borne on the tergo-pleural membrane, and vis-
ible dorsally, are seven pairs of spiracles (Sp), one
pair to each tergite. The first spiracle (Sp 1) is wide,
suboblong, soft-lipped and deeply set in the membrane.

It extends obliquely along the length of the lateral mar-
gin of the first tergite, and is arcuate on its anterior
edge. The second spiracle (Sp 2) is circular in shape,
with a chitinized stoma, and is located in a fold in the
pleural membrane very close to the lateral margin of the
second tergite (T 2). The third to seventh spiracles

are slightly smaller and rounder than the second, and

are located close to the lateral ridge.

Ventrally, the five visible sternites (S) are
heavily sclerotized, strongly convex, coarsely and irreg-
ularly punctate, and sparsely clothed with a fine pubesc—
ence.

The first ventral sternite (S 3) is morpholog-
ically the third or fused second and third sternites. The
anterior margin of the third sternite is sinuate and con-
tiguous with the posterior margin of the metasternal coxal
plates, except for a spear shaped anteriorly proJected
process fitting medianly between the coxal plates. The

posterior margin of the third sternite is shallowly

-29-

arcuate. The anterior margins of the fourth, fifth and
sixth sternites are shallowly arcuate, lateral margins
are subparallel, converging posteriorly, and the poster-
ior angles are somewhat produced, the prolongation becom-
ing somewhat more pronounced proceeding posteriorly. The
seventh sternite (S 7) is subtriangular, its sides arcuate,
and its apex slightly rounded. It is flexible and slightly
longer than the other sternites.

Remaining segments, both dorsal and ventral,
are visible only when extended, and act as a carrier for
the external genitalia. They are dealt with in a later

section.

Protrusible segments and genitalia of male: Plate 7,
Figures 1, 2, 3, 4.

When fully extended, the dorsal view of the
protrusible abdominal segments (Fig. 3) shows that the
eighth tergite (T 8) is nearly as long as the seventh
(T 7) and slightly narrower. It is longer than broad,
with sides subparallel, broadly rounded on its apical
half, nearly flat, and quite heavily chitinized. The
ninth tergite (T 9) is short and subquadrate, with the
posterior margin deeply emarginate, and the anterior
margin obliquely sinuate. The tenth tergite (T 10) is
narrower than the ninth at its base, elongate triangular
in outline and slightly longer than the ninth tergite.
The two latter tergites (T9-10) are less heavily chitinized,
and more flexible than the eighth. The anus (An) lies

-30-

Just below the tip of the tenth tergite on the dorsal
plane as shown in Figure 2.

The pleural areas are membranous in nature, and
very obvious when the protrusible abdominal segments are
fully extended (Fig. 2).

The eighth sternite (S 8), as shown in Figure
4, is subquadrate, sides subparallel to the apical fourth,
and then broadly rounded on its posterior margin. It
is nearly flat and moderately sclerotized. The ninth
sternite (S 9) is elongate, slender, sides narrowly rounded,
triangular for its apical third, and about three times
as long as its greatest width. The base is membranous,
but quite heavily chitinized at its apical end to act
as support for the tenth sternite (S 10) and aedeagus.

The tenth sternite (S 10) is ovate and flat, slightly
narrower at its base than the ninth sternite, about one-
third as long, and weakly chitinized.

7 The aedeagus of the male consists of a basal
segment (Bs), median lobe (ML), and two lateral lobes (LL).
The basal segment is chitinous ventrally, membranous dor-
sally, and shallowly rounded on its anterior margin. The
posterior margin is open, triangularly depressed, and
encloses the bases of the median lobe and the two lateral
lobes (Figure l).

The median lobe is expanded at its basal third,
elongate slender, and with sides subparallel and pointed
at its apex. Dorsally, the median lobe is chitinized for.

support, ventrally it is membranous.

-31-

The paired lateral lobes (LL) of the aedeagus
are one of the main characteristics in the identification
of this species (2) (Figure l). The exterior margin of
the lateral lobe is strongly angulated near its apex,
giving it a half spearhead shape. The interior margin
lies obliquely over the median lobe to meet the interior
margin of its opposing lobe about halfway down the aedeagus,
continuing down the median line to the base of the struc-
ture. The exterior margin starts anteriorly at the outer
posterior margin of the basal segment, and narrows pos-
teriorly to the angle of the apex. The apical angles

are sparsely pubescent.

Protrusible segments andggenitalia of female: Plate 8,
Figures 1, 2.

The eighth tergite (T 8) is subovigal in out-
line, with the sides almost parallel on the basal half,
shorter than the seventh tergite (T 7), membranous at its
base, but well chitinized apically. Its sides are flexed
downward to partially enclose the pleurites, and Just
below the flexed edge is the small eighth spiracle, which
is borne on the membranous pleural tissue.

The eighth sternite (S 8) is as long as the
seventh sternite (S 7), longer than wide, sides subpar-
allel and rounded to the apex. It is moderately chitin-
ized.

There is no differentiation as to tergal, pleural

or sternal regions for the ninth segment (OVSh), which

-32-

acts as an everted, membranous, cylindrical sheath for
the ovipositor when it is extruded (Figure l).

The ovipositor of the female is a long, slender,
transparent, cylindrical tube of a membranous nature (0v),
having its base contained in the ovipositor sheath (OVSh).
Within the cylindrical tube of the ovipositor, are two
elongate, slender, flexible, chitinous rods (Rd) which
serve to strengthen the structure. Near the apical end,
the ovipositor is enlarged to a bulbous structure, bear-
ing paired genital valves (Gv), which in turn bear small
terminal styli (Sty). The genital valves are slender,
elongate, and about three times as long as the cylindri-
cal terminal styli. The genital valves and styli are
sparsely and finely haired. (Figure l and 2).

10.

11.

-33-
LITERATURE CITED

Blatchley, W. S., 1910. Coleoptera of Indiana, Part
2, pp. 713-722.

Dietrich, Henry, 1945. The Elateridae of New York
State, Cornell University Agr. Expt. Station,
Memoire#269.

Fenton, F. A., 1926. Observations on the biology of
Melanotus communis and Melanotus pilosus.
Journal of Economic Entomology, Vol. 19, No. 3,
pp. 502—504.

Hawkins, J. H., 1936. The bionomics and control of
wireworms in Maine, Maine Agr. Expt. Stn. Bul-
letin #381, pp. 51—55.

Henshaw, Samuel, 1885. List of the Coleoptera of
America, north of Mexico.

Henshaw, Samuel, 1885. List of the Coleoptera of North
America, with third supplement.

Imms, A. D., 1924. A General Textbook of Entomology.

Junk, W., and Schenkling, 1925-27. Elateridae in
Catalogue Coleopterorum. 1925, part 80, pp.
263. 1927, part 88, pp. 373.

Kingsbury, B. F., and Johannsen, O. A., 1927. Histolog-
ical Technique.

Leconte and Horn, 1883. Coleoptera of North America,
pp. 186.

Leng, C. W., 1920. Catalogue of the Coleoptera of
North America, North of Mexico, pp. 174, 384,
389, 391, 440.

12.

13.

14.

15.

16.

17.

-34-

Leonard, M. D., 1926. A list of the insects of New
Yerk, Cornell University Agr. Expt. Stn. Mem-
oir #101, pp. 351-

Schwarz, Otto, 1906. Genera Insectorum, 46B Fascicule,
pp. 186-191.

Snodgrass, R. E., 1935. Principles of Insect Morphology.

Thomas, C. A., 1940. The Biology and Control of Wire-
worms (A review of the literature), Penn. State
College, Bulletin #392.

Valentine, J. Manson, 1942. On preparation and pres-
ervation of insects, with particular reference
to Coleoptera, Publication 3696, Smithsonian
misc. collections, V. 103, No. 6.

Van Zwaluenberg, R. H., 1922. External anatomy of
the Elaterid genus Melanotus (Coleop) with
remarks on the taxonomic value of certain char-
acteristics, Ent. Soc. of Washington, Proc. 24,
pp. 12-29.

KEY TO PLATE 1.

1. Habit sketch of frontal View of head.

Ant.......Antenna
AntS......Antenna1 sclerite
Clp.......Clypeus
E.........Compound eye
Ephy......Epipharynx
Fr........Frons
Fs........Fronta1 suture
Gal.......Ga1ea
LbPlp.....Labial palpi
Lig.......Ligula
Lm........Labrum
Md........Mandib1e
MxPlp.....Maxillary palpi
PAnt......Parantennal fovea
Plf.......Pa1pifer

2. Dorsal view of head.

Cvx.......Cervix
E.........Compound eye
Fr........Frons
Fs........Frontal suture
0c........0cciput
Poc.......Postoccipita1 suture

3. Lateral view of head and part of prothorax.

AntS......Antennal sclerite
Clp.......Clypeus
E.........Compound eye

Eps 1.....lst episternum
Fr........Frons
Fs........Fronta1 suture
Lm........Labrum

Md ...... ..Mandible
MxPlp...;.Maxillary palpi
Nt........Notum
PAnt......Parantennal fovea
Ptl.......Prosterna1 lobe
St 1......lst sternum

4. and 5. Mandibles.
Ac........Anterior condyle
D.........Dentes
Prs.......Prostheca

6. Dorsal view of labrum.

MOOOOOOOCLabPum

 

 

 

PLATE 1

KEY TO PLATE 2.

1. Ventral view of head and mouthparts.

Bst.....;.Basistipes
Cd........Cardo
E.........Compound eye
Gal.......Galea
Ge.....-..Genae
Gs........Gu1ar suture
Gu........Gula ,
LbPlp.....Labial palpi
Lc........Lacinia
Lig.......Ligula
Md........Mandible
Mt........Mentum
MtS.......Menta1 suture
MxPlp.....Maxillary palpi
Plf.......Pa1pifer
P1g.......Pa1piger
Smt.......Submentum
St........Stipes

2. Ventral view of maxilla.

Bst.......Basistipes
Cd........Cardo
Gal.......Galea
Lc........Lacinia
MxPlp.....Maxillary palpi
Plf.......Pa1pifer
St........Stipes

3. Dorsal view of labium.

LbPlp.....Labia1 palpi
Lig.......Ligula

4. Ventral view of labium.

LbPlp.....Labial palpi
Lig.......Ligu1a
Mt........Mentum
MtS.......Mental suture
Plg.......Pa1piger
Smt.......Submentum

KEY TO PLATE 3.

Ventral view of prothorax.

Cc........Coxa1 cavity
Eps 1.....lst episternum
Pa........Posterior angle
Pss.......Prosterna1 spine
PtL.......Prosterna1 lobe
St 1......lst sternite

Dorsal view of prothorax.

Lc........Latera1 carina
Nt........Notum
Pa........Posterior angle
Pss.......Prosterna1 spine
Sul.......Su1ca

Posterior view of prothorax.

Cc........Coxal cavity
Eps 1.....1st episternum
Lc........Latera1 carina
Nt........Notum
Pa........Posterior angle
Pss.......Prosternal spine
Sul.......Sulca

Ventral view of lst sternite.
Interior dorsal view of lst sternite.

Lateral view of lst sternite.
Cc........Coxal cavity
Pss.......Prosternal spine

PtL.......Prosternal lobe
St 1......1st sternite

 

PLATE 5

KEY TO PLATE 4. '

1. Ventral view of meso and metathorax.

Cc........Coxal cavity
Cx........Coxa
El........Elytron

Epm 2.....2nd epimeron

Eps 2.....2nd episternum
Eps 3.....3rd episternum
MsC.......Mesosternal cavity
MsS.......Mesosterna1 suture
St 2......2nd sternite

St 3......3rd sternite
Tro.......Trochantin

2. Ventral view of abdominal segments.

8 3.......3rd sternite
S 4.;.....4th sternite
S 5.......5th sternite
S 6.......6th sternite
S 7.......7th sternite

3. Dorsal view of meso and metathorax (Elytra and
wings removed). '

A l.......lst axillary wing process

A 2.......2nd axillary wing process
ANP.......Anterior notal wing process
Epm 3.....3rd epimeron
PN........Postnotum
PNP.......Posterior notal wing process
Psc.......Prescutum
Scl.......Scutellum

Sct.......Scutum

Sp 1......lst spiracle

T l.......lst tergite

4. Dorsal view of abdominal segments (Elytra and
wings removed).

Lr........Lateral ridge
Sp........Spiracles
T.........Tergites

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PLATE 4

KEY TO PLATE 5.

1. Elytron.
ES(9).....Elytral stria (nine in number)
2. Wing.

A l.......lst anal vein

A 2.......2nd anal vein

A 3.......3rd anal vein

A 4.......4th anal vein
C.........Costa1 vein

Cu 1......lst cubital vein
Cu 2......2nd cubital vein
M l.......lst medial vein
M 2.......2nd medial vein
R l.......1st radial vein
R 2.......2nd radial vein
Rs........Radia1 spur
Sc........Subcosta1 vein

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PLATE 5

KEY TO PLATE 6.

1. Metathoracic leg.

Cx........Coxa
Fm........Femur

Tar 1.....lst tarsus
Tar 2.....2nd tarsus
Tar 3.....3rd tarsus
Tar 4.....4th tarsus
Tar 5.....5th tarsus
Tb.....;..Tibia
Tc........Tarsal claws
Ts........Tarsal Spurs

2. Mesothoracic leg.

Cx........Coxa
Fm........Femur

Tar 1.....lst tarsus
Tar 2.....2nd tarsus
Tar 3.....3rd tarsus
Tar 4.....4th tarsus
Tar 5.....5th tarsus
Tb........Tibia
Tc........Tarsa1 claws
Ts........Tarsa1 spurs

3. Prothoracic leg.‘

Cx........Coxa
Fm........Femur
Tar 1.....lst tarsus
Tar 2.....2nd tarsus
.Tar 3.....3rd tarsus
Tar 4.....4th tarsus
Tar 5.....5th tarsus
Tb........Tibia
Tc........Tarsa1 claws
Ts........Tarsa1 spurs

4. and 5. Tarsal claws with pectinate teeth.
PT........Pectinate teeth

Tar 5.....5th tarsus
Tc........Tarsa1 claws

 

 

 

 

 

 

PLATE 6

KEY TO PLATE 7.

l. Aedeagus of male (Dorsal view).

Bs........Basa1 segment
LL........Lateral lobe
ML........Median lobe

2. Lateral view of protrusible abdominal segments
and aedeagus of male.

An........Anus
Bs........Basa1 segment
LL........Latera1 lobe
M.........Membrane
ML........Median lobe
7.......7th sternite
8.......8th sternite
9.......9th sternite
10......10th sternite
7.......7th tergite
8.......8th tergite
9.......9th tergite
10......10th tergite

iii-38802020303

3. Dorsal view of protrusible abdominal segments of
male; aedeagus not fully extended.

LL........Latera1 lobe
ML........Median lobe
T 7.......7th tergite
T 8.......8th tergite
T 9.......9th tergite
T 10......10th tergite

4. Ventral view of protrusible abdominal segments
of male; aedeagus not fully extended.

Bs........Basal segment
LL........Lateral lobe
ML...;....Median lobe
g....... th sternite
....... th sternite
9.......9th sternite
10......10th sternite
8.......8th tergite
9.......9th tergite

 

 

 

 

 

 

 

PLATE 7

KEY TO PLATE 8.

Dorsal view of protrusible abdominal segments of
female, with ovipositor fully extended.

Gv........Genital valve
Ov........Ovipositor
0vSh......Ovipositor sheath
Rd........0vipositor rod
Sty.......Stylus of genital valve
T 7.......7th tergite

T 8.......8th tergite

Apex of ovipositor.
Gv........Genita1 valve
0v........0vipositor
Rd........0vipositor rod
Sty.......Stylus of genital valve

Male antenna showing erect pubescence on inferior
margin of fourth Joint.

Female antenna showing pubescence on fourth Joint.

_~ “u.

.fl.‘ 1.". .' «'1 .m'

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PLATE 8

 

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