Proceedings of Scotts Turfgrass Research Conference Volume 1 - Entomology May 19-20,1969 \ RALPH W. MILLER Ex Libris Golf Library Industry Hills City of Industry, California s Proceedings of Scotts Turfgrass Research Conference Volume 1 - Entomology May 19-20,1969 EDITORS Herbert T. Streu Department of Entomology and Economic Zoology Rutgers University, New Brunswick, New Jersey Richard T. Bangs O. M. Scott and Sons Company Marysville, Ohio O. M. Scott and Sons Company • PUBLISHER Marysville, Ohio RALPH W. MILLER GOLF LIBRARY BOX 3287 CITY OF INDUSTRY, CALIFORNIA 91744 PREFACE This Proceedings includes the papers presented by the conference speakers and the subsequent dis- cussion by conference participants. It is the first Proceedings concerned with turfgrass research and treats Entomology, one of the many disciplines contributing to turfgrass management. Participants at the conference included 29 sci- entists from 27 states and Scotts research staff. At that time, some states had little or no turf- grass entomology research activity and those assem- bled felt that this may have been the first gather- ing of so many entomologists interested in turfgrass insect research. The conference was held at the research facili- ties of 0. M. Scott and Sons Company, Marysville, Ohio, and is the first of a series. As such, the editors wish to thank the speakers and participants for their cooperation in bringing this volume to completion. Proceedings of Scotts Turfgrass Re- search Conference, Vol. 2 - Pathology, is now be- ing prepared. H. T. Streu R. T. Bangs CONTENTS Preface Participants Toxicology of Insecticides Commonly Used in Turf Maintenance JOHN E. CAS I DA Control of Southern Chinch Bug (Blissus Insularis) in Brazos County, Texas PHILIP J. HAMMAN Turfgrass Insect Research in Florida THOMAS L. STRINGFELLOW Pesticides in Water H. PAGE NICHOLSON General Discussion Period Some Cumulative Effects of Pesticides in the Turfgrass Ecosystem HERBERT T. STREU Pesticide Residues in Tissues of Fishes from Native and Commercial Fisheries in the Mississippi Delta J, LARRY LUDKE vii 1 15 19 35 47 53 65 Biology of Turf Insects in Relation to Control JAMES A. KAMM . 77 Sod Webworm and Billbug Research Studies HUGH E. THOMPSON . 83 PARTICIPANTS J. WAYNE BREWER Assistant Professor Department of Entomology Colorado State University Fort Collins, Colorado JOHN E. CASIDA Professor of Entomology Division of Entomology University of California Berkeley, California GORDON FIELD Extension Entomologist Cooperative Extension Service University of Rhode Island Kingston, Rhode Island PHILIP J. HAMMAN Associate Entomologist Entomology Department Texas A 6c M University College Station, Texas ELVIS A. HEINRICHS Assistant Professor Agricultural Biology Department University of Tennessee Knoxville, Tennessee JAMES A. KAMM Research Entomologist Entomology Research Division Oregon State University Corvallis, Oregon DAVID L. KEITH Extension Entomologist Department of Entomology University of Nebraska Lincoln, Nebraska COSTAS KOUSKOLEKAS Assistant Professor Department of Zoology-Entomology Auburn University Auburn, Alabama J. LARRY LUDKE Department of Zoology Mississippi State University State College, Mississippi DEAN K. MCBRIDE Assistant Entomologist North Dakota State University Fargo, North Dakota BURRUSS MCDANIEL Associate Professor Entomology-Zoology Department South Dakota State Uiiiversity Brookings, South Dakota RICHARD L. MILLER Extension Entomologist Unit of Entomology and Economic Zoology Ohio State University Columbus, Ohio GERALD J. MUSICK Assistant Professor Department of Entomology Ohio Agricultural Research and Development Center Wooster, Ohio H. PAGE NICHOLSON Chief Water Contaminants Characterization Activity Southeast Water Laboratory Athens, Georgia GORDON R. NIELSEN Department of Entomology The University of Vermont Burlington, Vermont ROLAND W. PORTMAN Extension Entomologist University of Idaho Moscow, Idaho STANLEY RACHESKY Area Adviser-Pesticides Entomologist University of Illinois Chicago, Illinois ROSCOE RANDELL Extension Specialist Section of Economic Entomology Illinois Natural History Survey Urbana, Illinois ROBERT L. ROBERTSON Extension Entomologist School of Agriculture and Life Sciences North Carolina State University Raleigh, North Carolina JOSEPH L. SAUNDERS Assistant Entomologist Western Washington Research and Extension Center Washington State University Puyallup, Washington DONALD L. SCHUDER Professor in Entomology Department of Entomology Purdue University Laf'ayette, Indiana EVERETT SPACKMAN Extension Entomologist University of Wyoming Laramie, Wyoming LOYD L. STITT Pesticide Specialist Agricultural Biochemistry and Pest Control Division University of Nevada Reno, Nevada HERBERT T. STREU Associate Research Professor Department of Entomology Rutgers University New Brunswick, New Jersey THOMAS L. STRINGFELLOW Assistant Professor of Entomology University of Florida Plantation Field Laboratory Fort Lauderdale, Florida HUGH E. THOMPSON Associate Professor Department of Entomology Kansas State University Manhattan, Kansas GEORGE P. WENE Associate Entomologist Department of Entomology University of Arizona Tucson, Arizona ELLSWORTH H. WHEELER Professor of Entomology Leader-Pesticide Chemicals Program Department of Entomology University of Massachusetts Amherst, Massachusetts THOMAS R. YONKE Assistant Professor of Entomology Department of Entomology University of Missouri Columbia, Missouri TOXICOLOGY OF INSECTICIDES COMMONLY USED IN TURF MAINTENANCE John E. Casida Division of Entomology University of California Berkeley, California There is an increasing awareness in the scientific community, and among the public as a whole, that insecticides must be properly used or the short and long term effects in man and on the environment will exceed tolerable limits. In the context of the seminar subject, this means that insecticides for turf maintenance must be properly used or more problems will be created than solved. Most of these problems which may be created are general problems re- sulting from any use of insecticides. Within arthropod populations, de- struction of pollinators, predators and parasites is of great concern. Resistance limits the period of time during which the insecticide can be used, at practical dosages, before there is a selection of resistant pest strains. Persistent chlorinated hydrocarbons do an excellent job of in- sect control but their use is, in all probability, going to decline be- cause it appears that the effect of this continued use in the environment will exceed tolerable limits. It is abundantly clear that certain chlo- rinated hydrocarbons do give sizable residues in many parts of the envi- ronment and in human tissues, that these residues persist for a period of time, and that they do not, in some areas, degrade at a rate commensurate with their rate of introduction into the environment. There is a food chain accumulation potentially endangering certain birds and many verte- brate and invertebrate animals of the lakes and oceans. Situations of insecticide misuse have resulted in proposals, which have gained support, to restrict or even ban selected insecticide chemicals. Thus, there is justification for considering the persistence, degradation and toxicology of insecticides used in turfgrass entomology. Insect control in turf differs somewhat from that in agricultural situations. One major problem in agricultural entomology, that of resi- dues in food or feed, is not present in turfgrass entomology. Lawn treat- ment frequently involves mixtures of pesticides, or of pesticides with fertilizers and/or seed. These chemicals, individually or in mixtures, may be stored for years by the homeowner before use and, consequently, package and storage stability become of great importance. Insecticides generally are applied to agricultural areas by experienced persons, or under the advisement of qualified agents. This is not the case with turfgrass treatment where the user has little or no supervision and no instructions except those on the package label or, possibly, those pro- vided by the nurseryman. Children and pets are potentially exposed much more than in any other area of insecticide usage outdoors. Turf treat- ment occurs in surburban and urban areas under a tremendous range of climatic conditions. Extensive areas are treated, and not at dosages comparable to those used in agriculture, but rather at 2 to 5 times the dosage levels used in agriculture. Turfgrass treatments possibly are a significant source of environmental contamination by insecticides per- sisting in the soil or washing off in the surface or ground waters. My future discussion will concentrate on four insecticides frequently present in lawn-care products. These insecticides represent four different chemical types, each of a different mode of action and persistence charac- teristics. Fortunately, each of these four chemicals is the one of its class that will do the job with minimum hazard. Pyrethrins, piperonyl butoxide and methoxychlor are used for control of nuisance insects in the lawn. Chlordane, at about 5 lb/acre, and carbaryl, at the same dosage level, are important turfgrass insecticides. Let us consider these com- pounds in sequence. Pyrethrins and Piperonyl Butoxide An important crop in some parts of the world, particularly Kenya, is a species of chrysanthemum, Chrysanthemum cinerariaefolium, containing the insecticidal pyrethrins, which are obtained as a crude extract by appro- priate extraction of the dried flowers. The powdered flowers have actu- ally been used in insect control for at least 150 years. The extract con- tains six insecticidal esters, the most important being the pyrethrins, illustrated by pyrethrin I (Fig. 1). Pyrethrin I is a very complex chem- ical containing only carbon, hydrogen and oxygen. It is an ester with a cyclopropane group, a cyclopentenolone group and two unsaturated side chains. There are 16 possible isomers, but only the one shown occurs nat- urally. The safety of pyrethrins is established, in part, by studies with rats. The oral LD50 is 200 mg/kg and the dermal LD50 is greater than 1,800 mg/kg. When incorporated into the rat diet, no effect on the rat is de- tected at 1,000 ppm; at higher levels hepatic damage consists of slight bile duct proliferation. A dose just below the acute lethal dose can be administered daily for the lifetime of rats with little or no injury. There is no indication of tumor production. Human poisoning by pyrethrins is very unlikely. They are generally considered to be the safest insecticide in use. This is partially so be- cause of their long history of use without harmful consequences. In fact, they have ever been used without ill effects by oral administration as anthelmintics. Pyrethrins are poorly absorbed through the skin and are of low inhalation toxicity. Symptoms of acute poisoning are nervous manifes- tations. The safety of pyrethrins is probably the result of rapid break- down or detoxification in the mammal, although the chemistry of this break- down in the body is not fully understood. Injury is most frequently the result of an allergenic factor in the pyrethrins which gives a contact dermatitis similar to pollinosis, or an asthma-type reaction in a few sen- sitive persons, frequently those with a broad allergic background. Pyrethrins are never a residue problem when they are exposed, even briefly, to light. These materials are very light unstable, undergoing oxidation to non-toxic products by chemical changes on the two ends of the molecule (Fig. 1). Pyrethrins will not accumulate as environmental contaminants. Any problems resulting from their use will be from those organisms initially exposed. They are toxic to fish. Many species suffer paraylsis or death from dosages in the range of 0.1 to 10 ppm. Insects break down pyrethrins rapidly by an oxidative enzymatic proc- ess forming a non-toxic derivative (Fig. 1). This breakdown is so rapid that a second chemical, piperonyl butoxide, is usually added to impede FIGURE Is PYRETHRIN 1 AND PIPERONYL BUTOXIDE Extraction of Chrysanthemum cinerariaefolium flowers yields Pyrethrin I light oxidation occurs here Site of insect enzymatic oxidation A £f "DDT, -DDD and -DDE ranged from 83 to 98%. Results of analyses are expressed as parts per million on a wet weight basis. Samples were analyzed for DDT, DDD, DDE, toxaphene and endrin residues. Results and Discussion Residue levels of DDT, DDD and DDE in whole, insecticide-resistant mosquitofish were analyzed periodically from August 1968 to May 1969. Wholebody residues of DDT and its metabolites were found to be highest during the months of October (50 ppm) and February (84 ppm) after periods of extensive rainfall (Fig. 1). DDT was consistently higher than its met- abolites and in every month but November, DDD residue was greater than that of DDE. Toxaphene residues did not fluctuate, but showed a steady increase throughout the winter months—11, 82, 92 and 115 ppm for the months of August, October, November and February, respectively. Lakes were sampled eight times over an 11-month period from June 1968 to April 1969. There was considerable monthly variation among tissue sam- ples of each lake (Fig. 2). Although no seasonal trend is evident in the lakes as in the field drainage system, there does appear to be a relative difference between lakes. Residue levels in samples from Little Eagle Lake were consistently lower, ranging from 0.14 ppm to 0.79 ppm DDT plus met- abolites (mean 0.44 + 0.23 ppm). Lake Washington ranged from 0.19 to 1.70 ppm (mean 0.64 + 0.52 ppm). Tissue residues from Sky Lake ranged from 0.39 to 2.00 ppm (mean 1.93 + .61 ppm). Sky Lake was suspected of being the most contaminated lake studied because it receives large amounts Fig. 1. - Residue concentrations (ppm) of DDT, DDD, and DDE in whole-body samples of mosquitofish from drainage ditches. DOT — DDD DDE 40 30 20 10 ' S 1 F Fig. 2. - Residue concentrations (ppm) of DDT 1 O ' N plus its metabolites in muscle tissue of game fish from lakes in the Mississippi delta. 1 D lJ 1 M of drainage from surrounding agricultural land. The range and mean of res- idues of fish from Mossy Lake (range = 0.41-15.71 ppm; mean = 2.61 ppm) are higher than the values for Sky Lake. This is obviously influenced by the extremely high residue in the January sample. The fish was unusually small (7 cm length and 27 g total weight) and, thus, only the head and viscera were excluded from extraction. We can only speculate as to the cause of the high concentration in this tissue. Tharpe catfish residues were compared with the lake tissue residues (Fig. 2) and found to be consistently lower in muscle residues (range = 0.08-1.20; mean = 0.39). The catfish would be expected to have lower res- idues since they are in 10-40 acre ponds with high dams on all sides and usually with water pumped in from deep wells. However, the land on which some of the farms are located has been planted in cotton for many years. Also, we suspect the food source for most of the farms to be contaminated. Several other catfish farms were chosen for preliminary study and sampled at least once, except on occasions when farmers asked that more samples be run or when more data were desired. Catfish from 16 farms were sampled (Table 1) for muscle tissue residues and fish from 4 of these farms (Table 2) were tested for fat residues. The lowest mean value detected for the total of DDT, DDD and DDE was .032 ppm and the greatest value was .441 ppm (Table 1). The mean for total DDT and metabolites of all catfish farms was 0.179 + 0.105 ppm. The tissues from five of the sampling sites had res- idues over .200 ppm. These sites are near cotton fields which are heavily sprayed from late June to October each year. Table 1. Mean total quantities of DDT and its metabolites in catfish muscle (ppm). Farm Ce-1 Th-2 Co-3 De-4 Lu-5 Re-6 St-7 Wi-8 No. Samples DDT+DDD+DDE 2 10 4 5 3 9 2 1 .103 .340 .185 .214 .161 .147 .123 .441 Farm Min-9 Sk-10 Mil-11 Ha-12 Me-13 Ye-14 Br-15 Pr-16 No. Samples DDT+DDD+DDE 1 1 1 1 1 1 1 1 .218 .119 .111 .183 .149 .282 .050 .032 Coleman 1 Dean 5 Lupher 2 Table 2. Range and mean of pesticide residues found in catfish fat. Reed FARM: No. samples 6 Avg Residue (ppm) 4.76 2.14 1.79 8.54 18.58 DDT DDT DDE Total Tox. 6.79 2.94 3.76 13.52 45.88 0.72 0.74 0.74 2.21 * 1.95 1.80 1.59 5.34 * Range (ppm) DDT DDD DDE 3.05-8.00 0.95-3.75 0.24-3.75 -- -- -- * Toxaphene present but not calculated 3 .60-0.59 1 .40-4.20 1 .60-6.98 0.29-3.60 0.00-3.60 0.68-2.51 Fish from three farms had composite fat residues of DDT, DDD and DDE over 5 ppm (Table 2). The sample with the highest fat residue also had the highest residue concentration in muscle (Table 1, Wi-8). DDT concentration was greater than its isomers in every sample, except one. Toxaphene was present in catfish samples from two locations, but was not calculated. Although the residues of the muscle tissues from catfish farms were consistently lower than those in lake samples, there is considerable vari- ation among the farms. This indicates that there are factors causing in- creased levels of contamination in certain farms. Some of the farmers pump water into their ponds from bayous and ditches that meander through this area. These data illustrates the high levels of contamination which aquatic populations exposed to agricultural run-off may attain. This is certainly a hazard to susceptible predators and, potentially, to man himself. Possible dangers which may effect food-chain relationships are illus- trated by the following experiment. Susceptible green sunfish (Lepomis cyanellus) were fed resistant mosquitofish carrying pesticide residues picked up in the field (Table 3). Susceptible green sunfish fed resistant mosquitofish lived only one-half as long as did sunfish which were fed sus- ceptible mosquitofish and contained an average 11 times more total DDT, DDD and DDE than did control predators. Table 3. Pesticide residues in susceptible green sunfish fed a continuous diet of resistant mosquitofish. Sample 1 2 3 4 5 (control) 6 (control) Days Until Death DDT DDD DDE Total Endrin 7 28 28 44 91 97 1.18 0.85 0.62 1.70 0.04 0.22 2.35 0.13 0.46 1.06 0.02 0.15 0.78 0.49 0.62 1.89 0.06 0.22 (4.31) (1.47) (1.70) (4.65) (0.12) (0.59) 0.28 Only one sample contained endrin, the use of which was drastically reduced after 1963. Toxaphene was present in trace quantities in all sam- ples except the controls. Food sources used by some farmers for their cat- fish may be more contaminated than others, and some of the ponds are on land previously treated for cotton pests. Drift from nearby spraying may occasionally contaminate the ponds. The lowest composite residue (.032 ppm) found in muscle tissue of a catfish came from a pond which is several miles from the nearest pesticide-treated area. Summary Fishes living in drainage ditches and bayous near heavy agricultural drainage contain greater concentrations of pesticides than those living in lakes or commercial farm ponds. The amount of drainage and the nearness of lakes to treated areas is reflected in levels of pesticide residues found in the muscle tissues of native food species. Ditches reflect seasonal variation, probably due to drainoff, whereas lakes do not show a uniform seasonal trend. Tissues of fish from commercial fisheries contain less residue than naturally occurring populations. There are differences in the extent of contamination in commercial fisheries which seem to indicate there are practices or circumstances which may be altered in order to min- imize the level of contamination of catfish reared for human consumption. We are presently preparing a much more extensive program to monitor the aquatic environments in the Mississippi delta region. We intend to ana- lyze more tissues and tissue samples, water, soil and food sources to better determine the exact degree and sources of contamination. References Cited de Faubert Maunder, J. J., H. Egan, E. W. Godly, E. W. Hammond, J. Roburn, and J. Thompson. 1964. Clean-up of animal fats and dairy products for the analysis of chlorinated pesticide residues. Analyst 89:168. Ferguson, D. E., D. D. Culley, W. D. Cotton, and R. P. Dodds. 1964. Resistance to chlorinated hydrocarbon insecticides in three species of freshwater fish. Bioscience 14(11):43-44. Ferguson, D. E., and C. E. Boyd. 1964. Apparent resistance to methyl parathion in mosquito fish, Gambusia affinis. Copeia 1964. 4:706. Mills, P. A. 1961. Collaborative study of certain chlorinated organic pesticides in dairy products. J. Assoc. Offic. Agr. Chem. 44:171. Rosato, P., and D. E. Ferguson. 1968. The toxicity of endrin-resistant mosquitofish to eleven species of vertebrates. Bioscience 18:783-784. Vinson, S. B., C. E. Boyd, and D. E. Ferguson. 1963. Resistance to DDT in the mosquito fish, Gambusia affinis. Science 139:217-218. DISCUSSION PERIOD Dr. Stringfellow: Dr. Ludke, how did you get the 5 g plug you took out of the side of the fish? Dr. Ludke: The catfish were skinned. We tried to do it just as if they were being prepared for consumption. Then we took a scalpel and cut out a 5 g plug. Dr. Stringfellow: At the same location and proximity to the stomach? Dr. Ludke: Yes. They were directly on the side--pretty much underneath the dorsal fin. We would scale or skin the fish and cut out a plug. Dr. Stringfellow: What did you use for untreated control? Dr. Ludke: We're not really worried about untreated controls. All we were worried about in this particular experiment was comparing the three situations with the three populations. Dr. Stringfellow: In a strobane-toxaphene total chlorine analysis, DDT, dieldrin or some of the other total chlorine analysis, there is enough chlorine to read a part or two per million of some of the pesticides sim- ply from background interferences. How could you be sure the peak time and size of peak on your chromatograph were correct? Dr. Ludke: We did recoveries to see what percent recovery we were getting. We took catfish from a catfish farm in the eastern portion of the state and extracted those. Certain pesticides were added and, later, extracted. Mr. Westfall: Dr. Ludke, what is an acceptable level of DDT in fish? You showed us several instances with various levels, but what do you consider safe or acceptable? Dr. Ludke: The levels vary for the particular pesticide. I think Dr. Nicholson could give you a better idea than I could as to exactly what the tolerances are. I didn't point it out, but in one graph there was an endrin value. Endrin was sprayed very heavily in that region up to about 1963 or 1964. Endrin has a zero tolerance, so any residue is supposedly not accep- table. I'm not sure about the situation with toxaphene, DDT and its isomers. I think 5 to 7 ppm comes to mind. Dr. Stitt: I think the tolerance for DDT in fish has recently been estab- lished as 5 ppm by the Food and Drug Administration. Mr. Gabert: Dr. Ludke, on that bar graph where you analyzed residues month- ly in the different lakes, how many samples did you take each month? Dr. Ludke: As I stated, this was not planned as one study and that should be apparent. We've been studying the ditch-type situation for a number of years. These represent a number of samples with pooled samples in each case. When we started out we were going to make a very extensive study of the lakes, but we got sidetracked onto the catfish study and struggled to keep it up. The sampling area is almost 150 miles from where we were lo- cated. I realize the sampling there was scanty but I think it gives you a general idea of the differences between the various lakes. As a matter of fact, the lakes we expected to be the least contaminated were consistently the most clear, even on the basis of one sample. We hope to go back and do quite a bit more. Dr. Wittenbrook: Dr. Ludke, there has been a lot of interest lately in the mutagenic effects of pesticides. I was wondering if these resistant fish are actually mutagens, or are they the proper species? Dr. Ludke: I think they probably are not mutagens. This is based on what is known about insect resistance. We can take even susceptible populations and test them at various concentrations. From this we can actually get fish that will do pretty well in comparison with some of our less resistant fish in our resistant populations. The development of resistance appears to be by natural selection. Dr. Wittenbrook: One other question along the same line. I don't know how many fish you took out of there, but did you notice any minor differ- ences in these fish? Dr. Ludke: Are you talking about morphology? Dr. Wittenbrook: Well, some overt or obvious difference. Maybe a slightly different placement of the fin or something. Dr. Ludke: This is another thing we've wanted to do a study on for a good while, but we just haven't gotten to it. There is a definite behavioral difference. This is evident in two things. For instance, if we place a resistant or susceptible fish in a flowing system and give it a choice of going up channels with varied levels of pesticide, the resistant fish re- peatedly will choose the less contaminated spot (depending on the pesti- cide) . Also, the resistant fish are much more voracious. They are not nearly so secretive, but this could be due to the habitat, the presence of predators and so on. This difference, as far as choosing levels of pesti- cide concentration, leaves you to wonder. Dr. McDaniel: How did you feed those resistant fish to the predators? Dr. Ludke: In the case of the fish (bass, bluegills and green sunfish), all you have to do is put the resistant fish in the water and the predators hit him right away. We starved them for a week or two before we actually put the fish in. With the snakes, turtles and so on, you have to feed them forcibly. They're not natural predators. Dr. McDaniel: What conclusions are you drawing from this? Dr. Ludke: What we are trying to do is merely show the weight ratio, the level of contamination in the mosquitofish that would produce mortality. Dr. McDaniel: You are saying that DDT killed the predators. Is that right? Dr. Ludke: Yes. Dr. McDaniel: Did you know how much DDT was in that resistant fish at the time the predator ate it? Dr. Ludke: This wasn't DDT. The particular case that I showed was endrin. Yes, we knew actually how much was in the fish-about 4 micrograms. Dr. McDaniel: Have you sampled all of these? Are you able to indicate that the predator died by a poison rather than suffocated or choked? There are multiple factors that can be involved« Dr. Ludke: They exhibited very definite symptoms of poisoning. Plus, we had controls. We were feeding the same groups of fish that had not picked up the residues. Dr. McDaniel: You had a control of five samples that you fed the nonresis- tant strain. Is this correct? Dr. Ludke: I couldn!t tell you. I don't recall. Dr. McDaniel: What bothers me is that you have a strain here resistant to your insecticides. It must be resistant to many insecticides. Dr. Ludke: Yes. Dr. McDaniel: If it's resistant to many insecticides, you are accumulating data on a particular insecticide within that fish at that particular time. Dr. Ludke: In that case, yes. Dr. McDaniel: And now you are making interpretations in relationship to other insecticides? Dr. Ludke: No, in that case only to that insecticide. We also knew how much DDT was in the fish being brought in. Dr. McDaniel: Then which insecticide killed the predator? Dr. Ludke: Well, I would bet that the endrin did. In fact, I'm sure of it. Approximately four micrograms of endrin was going into the predators with at least 1,000 to 10,000 fold less DDT, and endrin is more toxic than DDT. It's more toxic to all of the birds that we fed and to the fish. I couldn't tell you for sure about some of the reptiles. Mr. Simmons: Dr. Ludke, would you review which pesticides you have picked up in those ditches? Also, how much DDT is used on the cotton crops in that area? Dr. Ludke: The principal pesticides we picked up are para, para'-DDT; para, para'-DDD; para, para'-DDE; toxaphene, and endrin before about 1964. We still pick endrin up on occasions, and some ortho, para'-DDT. We have gotten dieldrin on one or two occasions, but we seldom find it in our fish. I can't think of any others we find in any significant amount. Now what was your second question? Mr. Simmons: How much DDT is used on the cotton fields? Is it used each year and how many times a year? Dr. Ludke: I can't give you the exact information on that. I know they usually begin spraying in early July and go all the way through October. The principal spray mixture is a combination of DDT, toxaphene and methyl parathion. The rate of application varies with the particular parts of the delta. BIOLOGY OF TURF INSECTS IN RELATION TO CONTROL Entomology Research Division Research Entomologist Department of Entomology Oregon State University James A. Kamm Corvallis, Oregon We are now in the final conference discussions at Scotts and I wonder (1) whether we, as entomologist, have been provided with new perspectives, and (2) do we really know enough about our pesticide problems to effect- ively argue the pros and cons. In my opinion, one thing conspicuously absent from our discussions thus far is the lack of emphasis on the biol- ogy of the many turf pests in relation to the pest to be controlled. This is one of the fundamentals taught in economic entomology, to know something about the insect you are trying to control. I have selected as examples of turf insects, the sod webworm complex in Oregon and the billbugs as they occur in the Pacific Northwest. These insects illustrate the variation in the biologies of turf insects and the diversity of factors involved when considering a pest problem. In the course of our discussions, I will raise a few questions that probably will provoke controversy. I intend to perhaps stimulate some thought and show, from one point of view, that sometimes we tend to get entrenched in our research methods and often continue to work on a problem even though it is no longer worthwhile. The grass seed industry in Oregon presently consists of the following acreages: Kentucky bluegrass, 5,600; bentgrass, 8,160; ryegrass, 132,000: fine fescue, 18,000; red fescue, 14,500; tall fescue, 16,000, and orchard- grass, 10,000. All are grown in the Willamette Valley. The seed grass industry in Oregon is relatively new and includes well-organized growers1 organizations that constantly introduce new varieties. They are interest- ed in grasses, both for turf and forage, and seek new markets for their grass seed in the United States and abroad. Sod Webworms The life cycle of sod webworms is as follows. Eggs hatch to larvae which construct a shelter in the turf. There are many variations in shel- ter construction depending upon the habits of the particular insect, and it is difficult to generalize about sod webworms. For example, Crambus trisectus in Oregon is univoltine, but in the eastern United States there are 2-3 generations a year. The feeding habits of these insects also vary with the species. We found that C. trisectus feeds exclusively on the leaves of Chewings fescue whereas C. topiarius does equally well on either the roots or leaves. However, most of the sod webworms in Oregon feed on the chlorophyll-bearing part of the plant. Sod webworms overwinter as larvae and for years workers have failed to locate the specific overwintering stage. C. trisectus, for example, diapauses as very small larva inside a hibernaculum that is very difficult to find among the litter and debris in the sod. The Eastern form of C. trisectus has an ash-gray color not characteristic of the Oregon form. Perhaps the color variation is a result of the host on which the larvae feed. C. topiarius is probably better known as the cranberry girdler. Cur- rently, this is Oregon's worst pest in the sod webworm complex found in grass seed fields, and of the cranberry industry along the Oregon coast. In the Willamette Valley, it is a sporadic pest. The adults fly in June and lay eggs at that time. Larvae require little food during the summer but with the September rains, the grass resumes growth and the larvae feed voraciously. A heavy infestation of larvae will completely separate the roots from the shoots by their feeding activities. The fungus, Beauveria bassiana, often accompanies heavy infestations of larvae. Infected larvae turn a dull pink and become flacid. I suspect that B. bassiana is one effective natural control of sod webworms in Oregon, but control occurs only after the larvae have inflicted their feeding damage. C. bonifatelluns is a serious pest of lawns in the western United States. This insect rarely damages lawns in the Willamette Valley, but in eastern Oregon and California where it is quite dry, it is a serious pro- blem, primarily in the bluegrasses. It is not a pest in the production of grass seed in Oregon. bonifatelluns prefers a well watered and main- tained turf and is capable of devouring a lawn in the course of 4 or 5 generations each year. Although the moths of C. tutillus are frequently abundant, I have never observed noticeable feeding injury by the larvae. The moths emerge in May to lay eggs and the resulting larvae progress to the third instar. Growth is extremely slow through the summer but with the advent of cooler weather in the fall, the larvae resume feeding and then diapause as nearly mature larvae. The fact that C. tutillus grows so slowly indicates that it would not produce economic injury unless extremely abundant. The point I am trying to make is that the biologies of crambids are highly variable. Some species complete their life cycle in less than one month whereas others require a full year. Too often these insects are lumped together and called Crambus spp. Since the biologies of these spe- cies vary, the control should be tailored to a specific insect. To digress for a moment, I wonder if we in research are asking the right questions to be answered through our investigative efforts. I would like to illustrate this with a few comments on some data of Dr. Terriere's at the toxicology laboratory at Oregon State University. He measured the ability of the Japanese quail, the rat, the house fly, the rainbow trout and the blowfly to epoxidate aldrin. Not only were there great differences among these animals to perform the epoxidation of aldrin, but also between the male and female quail. Dr. Terriere feels that other animals vary in ability to detoxify aldrin and also vary in the metabolite produced. For example, some insects make DDE, others Kelthane, others DDD, etc. Many are more toxic than their parent compound. The problem is that aldrin and many of these metabolites become part of the ecosystem. I'm not sure it is realistic to ask the question, what levels of aldrin are harmful in our environment? At this time there is no reasonable way to get this information. But what must be decided in the near future is, are we going to invest more time on the chlorinated hydrocarbons and the persis- tent insecticides, or are we going on to the less residual materials? I have attempted to point out, by way of example, that there is not a prac- tical answer to Dr. Nicholson's question concerning what level of DDT is harmful. He found 1 ppb in his watershed studies and I believe he made the statement that it was unlikely this concentration is doing any damage. Dick Bangs mentioned that there is no information to argue the point one way or another. But the fact remains that a poison has accumulated in the environment. It is doubtful that another 30 or 40 years of research would give the chlorinated hydrocarbons a clean bill of health in relation to long term effects. Wouldn't it be easier to get the information necessary to formulate short residual materials with a controlled release? It seems far easier to develop a battery of insecticides that are biodegradable to harmless by-products than to attempt to prove that residual insecticides have no harmful effects. There is something we can do to reduce the source of pollution by insecticides. For example, Scotts and many of its competitors formulate turf products with various insecticides. Often, homeowners see the moths of sod webworms fluttering about their lawn and immediately feel that in- sects are consuming their grass. Usually, in Oregon, there is no relat- ionship between the number of adults present and the larvae that do the damage, yet the lawn is treated every year. Is this a source of pollu- tion in metropolitan areas? Billbugs Now, I would like to turn to the biology of the billbug, Sphenophorus venatus confluens, which is native to the United States. Several years ago Oregon growers reported failing stands and reduced seed yields or orchard- grass as a result of billbug damage. Until the advent of commercial seed production of orchardgrass in 1957, it was grown only to a limited extent in Oregon. In the last decade the acreage of orchardgrass has increased to 10,000 acres, most of which was grown in the Willamette Valley. The current outbreak of billbugs was undoubtedly correlated with the increased acreage of orchardgrass which apparently is an ideal host for the billbug. In the spring the females chew a hole in the stem of orchardgrass at the base of the plant and then deposit an egg inside the cavity. The lar- vae develop inside the stem until the diameter of the stem restricts growth, then they chew an exit hole, leave the stem and initiate feeding on the roots. As the larvae feed, the root is severed from the shoot. Heavy in- festations of billbug larvae may destroy the entire stand of orchardgrass. Prior to the billbug problem in orchardgrass, S_. v. confluens was not an economic test although commonly found in bluegrass and bentgrass lawns. The close relative, S>. venatus vestitus, is a severe problem in turf in Florida, as Dr. Stringfellow mentioned; in Kansas, as Dr. Thomas indicated, and more recently has infested turf in California. S^. parvulus and S^ cicatristriatus sporadically damage bluegrass and bentgrass lawns in the Pacific Northwest, but none of the billbugs present enough of a problem to require yearly control. In the case of S_. venatus confluens, we detected a distinct peak of adult activity in April. By application of 3 lbs diazinon, or 1 lb aldrin per acre, very effective control was achieved, but only if applied during the peak activity of the adults in April. It appears to be an impossible task to control the larvae of the billbug since they are well protected in the crowns of plants and in the soil. The most severe larval feeding dam- age occurs in August. Systemic insecticides failed to give adequate con- trol due to their rapid translocation to upward parts of the plant. Con- sequently, a billbug problem must be detected and treated in the spring before adults lay their eggs. Oregon growers were desperate for a good insecticide to control bill- bugs and frequently resorted to massive dosages in attempts to control this pest. In some cases they were successful, but more often than not their efforts failed. After investigating the life cycle of the billbug and learning the proper time to apply the insecticide, 1 lb of aldrin effective- ly controlled the adults whereas 4 lbs failed to control the population when applied to kill the larvae. The point I have tried to make is that exces- sive dosages of insecticides are not substitutes for good biological infor- mation in the control of a pest. Effective control programs are based on a thorough knowledge of the insect's biology and, often, the byproduct is a reduction in pesticide pollution of the environment. DISCUSSION PERIOD Dr. Heinrichs: Do you know how many sod webworm species occur in Oregon? Is there a list of these? Dr. Kamm: I believe we have in the neighborhood of 10 species associated with grass seed fields. We have other species that are commonly found in -high mountain ranges. I'm reasonably confident that the number of common species we have would approach 18 or 19. Dr. Heinrichs: How about rearing these? Do you rear these in a laboratory? Dr. Kamm: Yes we do. I have, as have other workers, experienced much in the line of difficulty in trying to rear these insects. Bohart, in Cali- fornia, attempted to rear Crambus in stender dishes using grass clippings. This method is time consuming and often mold collects in the cultures. I have used this method in my diapause experiments using Chewings fescue which does not mold as readily as other grasses. I have a graduate stu- dent who will be completing his Master's Degree on the rearing of these on an artificial diet. As I recall, he has a diet that gets out about 85% of Crambus trisectus to adults. One of the problems encountered in rearing the moths is that they must mate the same night they emerge or otherwise their fecundity drops to the extent that you may not get any eggs at all. I have also been interested in the Beauveria bassiana as a possible biolog- ical control agent. The mold inhibitors we use in the diet are fairly stout and, from preliminary work, are also toxic to Beauveria. One interesting situation that involves the rearing of Crambus trisectus is that on some hosts it does quite well. However, if we rear trisectus on this to the third generation, those insects that emerge won't lay fer- tile eggs. I've had large numbers of moths and haven't been able to iden- tify the problem. I believe there is a nutritional deficiency involved. The host, if you are using grass, is important. There are many ramifica- tions in the successful culture of these insects. I don't think we have a feasible method at this time for laboratory culture, due to the amount of work involved, but I believe we can improve our methods. Dr. Kouskolekas: I would just like to add that there has been a recent report in the Journal of Economic Entomology from work done in Kentucky. It was on the rearing of sod webworms, if someone wants to cross check on the ingredients and the mold inhibitors. Dr. Kamm: You are right. The paper you are referring to was done by Dr. Pass. He took a different approach than we did and used a bluegrass extract mixed in the diet. We have formulated a meridic diet in order to study the the effect of particular nutrients. We were able to successfully identify the compound that stimulated their larval feeding. Mr. Simmons: Dr. Kamm, I wondered if you would briefly touch on the number of generations of sod webworms you have in the seed fields and what are the insecticides generally recommended for control? Dr. Kamm: We approach insecticides this way; we don't make any recommenda- tions for sod webworms in the Willamette Valley. In eastern Oregon where the principal economic problem is, we recommend diazinon which seems to be effective. We have two species there which are univoltine-Crambus plumbi- fimbriellus and Crambus vulgivagellus. They occur in mixed populations. Mr. Simmons: I think we are all interested in new chemistry, as far as in- secticides or any other compounds are concerned, but I wonder if this con- cern with the chlorinated hydrocarbons is not just a point in time and once this situation becomes resolved we will be concerned with the envir- onmental effects of the phosphates or carbamates? Dr. Kamm: Yes. This is very true. More than likely the chlorinated hydrocarbons will pass out of the picture, then other things will be in the limelight. DDT is the most pressing problem at this time; the other chlorinated hydrocarbons will be next. The thing that alarms me is that one rarely sees any information on the other insecticides. For example, a good deal is known about the degradation of diazinon. It dissipates fairly rapidly, yet I'm not sure that we know anything about the biolog- ical pathways, end products or if they accumulate. This is the type of information that is lacking. I don't think our attempts to justify the use of the chlorinated hydrocarbons will pay great dividends. Mr. Simmons: I'll make one or two points on those comments. One is that there are materials that do a specific job for a specific use. We prob- ably will continue to need those particular chemicals in our program for quite some time, and to continue using them we will need to develop more information. This is why there will be some continued work going on in this area. We also look for new activities, more effective activities and, certainly, safer activities wherever possible. SOD WEBWORM AND BILLBUG RESEARCH STUDIES Hugh E. Thompson Associate Professor Department of Entomology Kansas State University Manhattan, Kansas I was interested in following Dr. Kamm because we are working with a billbug that, as far as I can determine, is present in all stages all of the time. Note in Table 1 that on May 14, 16 we found only larvae in our experimental plots. We counted several 1 sq ft blocks out of 1,000 sq ft plots and found no adults, but at the same time the sod nursery people were operating a sod cutter in an adjointing field which was contiguous with the one we were working in. They were taking this sod to their stores for sale and adult billbugs were crawling out across the sidewalk from the sod. Even though we missed them in our counts, there were obviously some adult billbugs present. One of the reasons we started on our control programs sooner than we wanted to was to prevent the sod nurserymen from distributing the insect while selling their sod. It's easier to control it in the nursery than it is to treat all the lawns where infested turf was installed. Although Tom Stringfellow stated that the hunting billbug doesn't bot- her them too much down in Florida, we have lost zoysiagrass lawns in south- central Kansas because of this insect. We do know a little bit about the hunting billbug (Sphenophorus venatus vestita). On zoysiagrass the larvae tunnel through the rhizomes and the last ins tar occurs in the soil. We are doing biological studies along with some of our control work. During the week between Christmas and New Year's, we found both adults and larvae present in the soil in Witchita. The adults were about \\ in- deep and the larvae occur 2\ in. to 3 in.deep in the soil. They usually remain at that depth through the month of May, then gradually move closer to the surface. In some of my early control programs, where I applied insecticides in May, I think the chemical didn't penetrate deep enough to kill the lar- vae. Because we had about 40,000 sq ft of bermudagrass available for our research, we made our blocks 50 ft by 20 ft. Some work with 10 ft by 10 ft plots was done in a smaller zoysiagrass area. Results of this work are presented in Tables 1 - 5. We didn't use any of the chlorinated hydrocarbons because of previous work by Kerr in Florida. We were interested, however, in getting some data on Baygon for Kansas because of its impending use for control of this insect. Dursban was used in early tests, and appeared to give the best control. Scotts Cope Plus, also tested, controlled 507o of the billbugs. Table 1. Comparative Numbers of Adults, Papae and Larvae of Hunting Billbug in Selected Plots in Myers Nursery at Various Dates. (Check plots 2, 15 and 17 only include.) 5-14 5-26 Date 7-11 7-19 8-7 1 31 P 0 a* 0 1 30 P 0 a 0 1 22 P 0 a 6 1 28 P 3 a 7 1 22 P 12 a 9 Percent Control larvae pupae adult 100 0 0 100 0 0 79 0 21 74 8 18 56 25 19 * 1 = larvae, p = pupae, a = adults Table 2. Control of Hunting Billbug Larvae on Midway Bermuda (Myer's Nursery, Wichita, Kansas). 1968 Treatment Block 1 6 2 3 5 0 0 Check Baygon Lannate Galecron Dursban 4 5 2 3 1 1 2 0 2 2 2 0 3 0 11 7 2 15 17 3 1 0 1 0 0 2 1 0 0 0 0 1 0 1 0 0 0 2 1 2 0 1 1 0 4 2 2 5 0 1 0 5 0 0 0 0 1 0 1 6 0 3 6 13 Total No. 5/14 7/11 5/14 7/11 5/14 7/11 5/14 7/11 5/14 7/11 5/14 7/11 8 5 9 22 1 2 1 4 6 8 3 17 21 10 36 67 1 0 0 1 15 3 9 27 3 19 10 32 11 7 5 23 10 14 7 31 10 7 12 29 3 1 0 4 0 4 2 2 1 1 0 3 3 0 1 0 0 4 6 1 6 0 0 0 2 1 3 0 2 2 1 0 0 1 0 4 0 3 1 2 0 1 2 2 2 3 3 2 0 1 0 3 5 0 1 4 1 2 1 9 14 4 11 16 8 10 18 7 0 12 0 0 0 0 1 2 7 9 10 4 10 10 1 1 4 1 1 0 3 1 0 0 0 0 0 0 0 Percent Control 84.7 9.3 Treatments applied May 17. 3 oz actual per 1,000 sq ft Sample No. 1 = southeast corner of plot; No. 2 = center; No. 3 = northeast; No. 4 = northwest; No. 5 = southwest Table 3. Control of Hunting Billbug Adults on Midway Bermuda (Myer's Nursery, Wichita, Kansas.) 1968 Sample No, 3 Total Treatment Block No. 5/14 7/11 5/14 7/11 5/14 7/11 5/14 7/11 5/14 7/11 5/14 7/11 Check Baygon Lannate 2 0 15 0 17 0 3 0 6 0 13 0 1 0 9 0 14 0 Galecron 4 0 11 0 16 0 Dursban 8 0 10 0 18 0 0 0 2 3 0 0 2 2 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 1 1 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 2 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 2 0 0 0 0 2 0 0 0 Treatments applied May 17. 3 oz actual per 1,000 sq ft 2 0 1 0 3 0 6 0 3 0 0 0 0 0 3 0 4 0 0 4 3 0 0 11 0 0 0 0 0 7 7 0 0 1 0 0 0 0 0 1 Table 4. Control of Hunting Billbug Larvae on Midway Bermuda (Myerfs Nursery, Wichita, Kansas.) 1968 Sample No. Treatment Block Check 2 0 15 2 17 2 Total No. 7/11 7/20 7/11 7/20 7/11 7/20 7/11 7/20 7/11 7/20 7/11 7/: 8 1 5 13 9 8 22 22 0 6 1 6 10 23 1 11 3 27 27 0 2 3 0 0 0 1 5 0 0 1 0 0 1 0 2 1 0 0 3 0 3 1 0 1 2 0 2 1 2 0 0 1 1 0 5 5 4 7 1 6 3 0 5 0 0 4 2 0 6 2 Cope Plus 5 0 7 1 12 3 Percent Control 50 0 0 83 Percent Control When we make counts the insect is present as adult, larvae, pupae and probably eggs, although we haven't counted the last. Notice in Table 2 that Baygon gave fairly good larval control, but Dursban was considerably better. Neither material was very effective against adults, so we think larvae are going to be the stage to control. Table 5. Control of Hunting Billbug Adults on Midway Bermuda (Myer's Nursery, Wichita, Kansas, 1968.) Sample No. Treatment Block Total No. 7/11 7/20 7/11 7/20 7/11 7/20 7/11 7/20 7/11 7/20 7/11 7/20 3 Percent Control Check 2 0 15 0 17 2 Cope Plus 5 0 7 0 12 2 0 0 1 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 1 0 0 0 0 0 0 1 0 2 2 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 1 2 0 1 0 0 0 0 2 1 3 6 0 1 4 0 3 2 5 2 2 0 The research plots in Tables 4-5 were treated with 25 lbs Scotts Cope Plus (carbaryl and chlordane plus fertilizer) on July 11 and posttreatment counts taken July 20. The results of the work with Cope Plus are presented in Tables 4 and 5. I'll confess one thing, we did not give Cope Plus as long to work as we did the others. We only allowed about one week between the time we made the application and the first count. Another count in late December revealed billbug adults and larvae still there, whereas with some of the other treat- ments, they were not. We also had some 10 ft by 10 ft control plots on zoysia (Tables 5A, 6 and 7). A 1 sq ft sample close to the center of each plot was dug out and examined for larvae and adults. We are pleased with Akton, as they are in Florida. It was found effective against both the larvae and adults. Data was compiled on the control of adults, larvae and pupae and gives a better picture of total control. Akton was still giving us a 1007o control six months after the time of application. Although we are interested in the life history of this pest, the problem is a mixed population of adults and larvae at the same time. I don't think it ever goes into a diapause. Table 5A. Control of Hunting Billbug Larves in Zoysiagrass (Wichita, Kansas, 1968.) Sample No 3 • 2 1 4 5 Total Treatment Check VC 13 Akton TH 427 I Dasanit 7/11 12/31 7/11 12/31 7/11 12/31 7/11 12/31 7/11 12/31 7/11 12/31 10 6 6 3 3 22 15 16 12 13 4 2 0 2 1 1 0 0 1 0 1 0 2 2 2 1 1 0 0 0 1 0 1 1 1 1 0 0 1 0 1 1 0 0 1 7 6 5 4 4 3 3 2 2 3 0 0 0 0 0 Table 6. Control of Hunting Billbug Adults in Zoysiagrass (Wichita, Kansas 1968.) Treatment Check VC 13 Akton TH 427 I Dasanit ] 0 0 1 0 2 0 4 0 2 0 e I 0 1 0 0 0 1 0 1 0 0 S ampi 3 e No. 4 0 0 0 0 0 1 0 1 0 0 0 0 1 0 0 0 0 0 0 0 5 0 0 0 0 0 0 0 0 0 0 Total 0 1 2 0 2 0 5 2 2 0 Table 7. Control of All Stages of Hunting Billbug in Zoysiagrass (Wichita, Kansas 1968.) 1 2 Sample No. 3 4 5 6 Treatment Check VC 13 Akton TH 427 I Dasanit 7/11 12/31 7/11 12/31 7/11 12/31 7/11 12/31 7 11 12/31 7/11 12/31 12 11 8 7 10 26 23 21 16 20 0 0 0 0 0 7 6 6 4 4 2 0 0 2 0 5 1 0 4 1 1 0 0 1 0 4 3 4 2 3 1 0 0 1 0 1 1 0 0 1 2 2 2 2 2 Per- cent Con- trol 29.5 100 11.9 60.7 Per- cent Con- trol 78.6 100 0 74.0 Another sod webworm, Surattha indentella, damages buffalograss, a native grass that many of our golf courses prefer to keep as fairway grass. They mow it very short. They have sand greens or, where they are getting water to their golf courses, they are using bentgrasses for greens. The webworm has one generation a year and damages bermudagrass so severely that weeds come in. The webworm makes a tunnel into the soil about four inches and lives in it. Where the tunnel comes out they extend a silken tube across the top of the ground. When they come in contact with a grass plant they stick their head out, cut the grass plant off and then pull it down into the tun- nel. They will put 3 or 4 grass plants in the vertical tunnel during the night. As far as I can tell, they never come out of those silken tubes more than to stick their head out far enough to chew off the grass plant and pull it in. We spent many nights on the golf course with flashlights to make this observation, and found that we had to lie on our stomachs for 2 or 3 hours before we began looking for them. Only then could we find them with their heads out cutting off the grass plants. The male is considerably smaller than the female, and when the female is gravid it is not able to fly more than 2 or 3 in. above the ground. A biological study on this insect has just been completed by Sorensen, who has made notes on its distribution and life history (Sorensen and Thompson 1969). He is continuing his work on the factors that influence the life history. Determination of the sex ratio was a problem. Using a standard mos- quito light-trap, only one female was caught during the summer of 1967. It was discovered, however, that a large number of female webworms were crawling around on the ground underneath the light-trap while it was ope- rating. As a result, a large hole was made and the light-trap placed so the top of collector was level with the ground. When females hit the baf- fles they fell in, and we were able to collect about one female for each male in 1968. We are working on the life histories of these two turf pests but, in the meantime, we are being asked to provide control recommendations. It does present some problems when you have a mixed population of all stages, as with the billbugs. I agree with Kamm that we need to know as much of the biology as possible before making recommendations, if we have the time. How- ever, golf course people, sod nurserymen and homeowners can exert a lot of pressure to get answers right now. Sorensen, K. A. and H. E. Thompson, 1969. Distribution of Surattha indentella Kearfott on buffalograss. J. Econ. Entomol. 62:750-2. Reference Cited DISCUSSION PERIOD Dr. Stringfellow: How extensive is your sod industry? Dr. Thompson: In Wichita, we have four large sod nurseries with somewhere between 35 to 50 acres of sod in each. Mr. Simmons: What about Baygon? How effective is it as a control for bill- bugs? Dr. Thompson: Over a five week period, we did get the population down to about one-tenth of what it was before the applications. Itfs a real dif- ficult thing. You can get your data biased by the fact that you make ap- plications with various insecticides, then your cooperative comes along and cuts out some sod with a sod cutter. When he rolls the sod back, all of these billbugs are laying there. The cutter goes through right at the level where most of the billbugs are located in the middle of July. They believe that what you did, didnft control them. I think Baygon was accep- table at the time we did this work, but I would go with Akton as my strong- est recommendation. It's a real heavy application. I want to do some gradation as different dosages to determine whether we can cut Akton back a little. It runs pretty close to 10 pounds in this work.