LIBRARY October 19»*5 gTATE PLANT BOARD E-673 United States Depeurtment of Agriculture Agricultural Research Administration Bureau of Entomology and plant Quarantine SUMMARY OF DDT EIPERIMEaiTS ON INSECTS l/ THAT AFFECT MAN AND ANIMALS By W. E. Dove, Division of Insects Affecting Man and Animals The development of DDT Insecticides at Orlando, Fla., and their use hy the armed forces since 19^3, eus veil as tests made hy other workers of the Bureau of Entomology and Plant Quarantine and Its cooperators, have demonstrated that practical control of certain In- sect pests of man cuid animals ma^r be obtained vlth these Insecti- cides. The experimental vork at Orlando was conducted under a transfer of funds, recommended by the Comnlttee on Medical Research, from the Office of Scientific Research euid Development, emd the re- sults vere made available to the armed forces In veurlous reports. The present report Is bcused on Information gained from tests made under conditions found In civilian life by workers in the Division of Insects Affecting Man and Animals, In some cases with the cooperation of other agencies. Many of these tests were sug- gested by the findings of the Orlando group. It should be under- stood that many of the tests were seasonal or regional In nature, and that no recommendations for the practical use of DOT Insecti- cides against any of the Insects are Included in this report, Bodj Louse At Orlando it was found that a concentration of 0.25 percent of DDT In diluents such as talc or pyrophylllte will give complete kill of the body louse (Pedlculus humanus corporis Deg. ) when applied to infested clothing. This concentration Is too low, however, to give lasting effects. When an Individual's clothing is treated at the rate of 1 oimce of a powder containing 5 percent of DDT, the powder is effective for 10 to Ik days. When the same amount of a 10-percent poT'/der is applied, protection against relnfestatlon lasts for approx- imately 21 days. Since the Incubation period of louse eggs seldom exceeds 21 days, a single application of the powder will eradicate an infestation, DDT has no ovlcldal properties; however, the newly hatched lice are klllled by the DDT residue. l/ Includes other arthropods, such as mites and ticks. - 2 - Two methods of impregnating clothing have "been developed. One method conslets in dipping garments in a volatile solvent containing TSDI, A dry-cleaning fluid such as Stoddecrd's solvent, or a light pe- troleum fraction such as gasoline, was found to be suitable for this purpose. Another method, designed especially for use in the field, consists in dipping garmfiiits in an emulsion of DEfT. When either loe- thod is employed, the clothing is wrung out and then dried. Both me- thods «ire equally effective, Hesid Louse DDT was Just as toxic to the head louse (Pedi cuius humanus humanus L.) as to the body louse. Because it was combed from the hair, two applications of the 10-percent DDT powder, about 10 days apart, were applied. The second application Idlled the newly hatched lice before they were old enough to lay eggs. In practical tests on a large scale a single treatment with a 10- per cent powder gave com- plete control in almost all instances. Crab Louse The 10-percent DOT louse powder was used against the crab louse (PhthiruB pubis (L,)), Two applications made at intervals of 10 days vere con5)letely effective in a large number of teste. Cattle Lice At Dallas, Tex., R. W. Wells and W. T, Hunt found that louse powder containing 10 percent of DDT killed the motile stages of the short-nosed cattle louse (Haematopinus eurystemus Nitz.), the long- nosed bloodsucking louse (Linognathus yitull (L.JT, and the cattle biting -louse (Bovicola bovis (Nitz,)'). A single treatment applied to only a portion of the body was not sufficient for killing all lice on the £uilmal. Dipping of cattle was more effective than dusting or spraying. The short-nosed louse succumbed to a dip containing 0,03 percent of DOT in a soluble-pine-oll emulsion, but not all the long- nosed lice were killed by this ooncentratlon. A single treatment with a dip containing 0.2 percent of DOT eliminated infestations of both the long-nosed bloodsucking louse and the short-nosed cattle louse. Goat Lice At Ifenard, Tex,, H, E, Parish and C. S. Rude found that a dip application of 0,2 percent DOT in soluble-pine-oll emulsion, in which •2 quarts of the liquid adhered to each anlraal, gave complete control of all stages of the four species of lice that occur on goats in that section. The dip left in the vat was effective against motile stages of red and yellow biting lice (Trlchodectes sp. ) and the blue bloodsucking lice (Linognathus sp,) on goats for more than 99 days after it was first used. Following these preliminary tests herds of goats were treated with the same formula, and it now appears tliat lice may be eliminated on a ranch if every animal is dipped and no infested ones are permitted on the premises. - 3 - CtoatB dipped in a soluble-plne-oll emulsion containing 0.1 per- cent of DDT were sheared 5 days later, and all motile lice vere found to "be dead. At Beltsvllle, Md,, E. A. Back exposed the mohair clipped from the animals to larvae of the carpet beetles Attagenas plceue (OUv. ) and Anth^us rorar (Waterh,). Approximately 3 months later about elght-rBntSs~of the larvae on the treated material had died and the other £1 appeared sluggish and starved. Larvae kept on untreated mnhair were alive ai^ appeared healthy. The results of this and similar tests suggest that the 0.1 percent DOT dip may Impart to mo- hair a good resistance against hungry larvae for a storage period of 3 monthB or longer. Hog Lice In Georgia and Florida W. G. Bruce and A. L. Smith found that a soluhle-pln©-oll emulsion containing 0.2 ^rcent of DOT was effective in killing motile stages of a hog louse, Haematoplnus adventlclus Hewm. Spray applications were effective during the first week, but not for 13 days after treatment. Owing to the hogs' habit of bedding together, the treated hogs rapidly reduced the infestation among all the hogs present. Two treatxaents with 0.2 percent of DOT emulsion eliminated all the lice. Poultry Lice At Menard, Tex., H. E. Parish found that the dusting of individu- al hens with a shaker can containing 5 percent of DOT in pyrophylllte ft>eed them of lice. Whether the material can be applied safely in a dust, spray, or aerosol to poultry in houses is not known. Its tox-- ioity to fowls must be determined before large-scale tests are under- taken. Mosquitoes Tests made with liquefied- gas aerosols against Anopheles quadrimaculatus Say show that pyre thrum is more effective than DOT, in both knock-down and kill. DOT, however, causes a high kill of moequi- toes when used at concentrations effective against flies, and its use In oomiblnation with pyrethnoa allows about a 25-percent reduction in the amount of pyrethrum without loss in killing power. On the basis of these tests the following formula has been used (figures In per- cent): Pyrethrins O.U, DOT 3, cyclohexanone 5, motor oil 5, and dichloirodifluoromethane 86.6. The formula is about equally effective a^sdnst flies and mosquitoes. A DOT-pyre-Uxrum spray can be finely dispersed mechanically and is equally as effective eu9 the liquefied-gas aerosols. An effective concentrated- spray formulation is DOT 20, pyrethrins 3, cyclohexanone 20, motor oil 5, and kerosene 52 percent. - u - J. B. Gahan applied DIXP sprajrs that left a residue on the inside walls and ceilings of residences, bams, and poultry houses in two 9-square-iiiile areas near Stuttgart, Ark, In one area an average dos- age of 56 mg. of DOT per square foot reduced the number of A. quadrimaculatus 9I percent in 3 l/2 to k 1/2 months. In the other area an average rate of 208 mg. of DDT per square foot reduced such mosquitoes 99 percent during the same period. Tests vith DDT in the laboratory at Orlando, Fla., showed that Dnr was effective but less toxic to larvae of Culex quinquefasciatus Say and Aedes aeggrpti (L.) than to comparable larvae of Anopheles quadrimaculatus . In field tests in Florida dusts applied at the rate of 0.1 and 0.05 pound of DDT in talc per acre gave complete or near complete control of A. queidrittaculatus and __A, crucians Wied, Dosages of 1 to 2 pounds of DDT per acre, in areas having a uniform growth of vegetation, prevented all but negligible larval development for k to 8 weeks. On account of the shifting of surface films by winds, a Tnlnlmum killing dose of 0.1 pound of DOT per acre ecp-pearei preferable to the larger dosages for routine applications. Oil solutions containing 5 percent of DOT (weight per volume), applied at the same rates as the dusts, were also effective for the same species provided adequate coverage of the breeding areas weis ob- tained. Finely atomized sprays produced by paint-type spray equip- ment, or from airplanes using equipment developed by C, N, Husman and "oTlir Longbcy at Orlando, were satisfactory for this purpose. When applied asl a fine spray to the breeding areas, an emulsion containing 32OT 20, Triton X-100 (an aralkyl polyether alcohol) 20, and lylen© 60 percent by weight, and used at the rate of 0.1 pound of DOT per aare, was equally as effective as the same amount of DOT applied in oils. In stabilized pools where emulsions were mixed with the water at the rate of 1 part of DOT to 1 million parts of water, the breeding of Anopheles mosquitoes was prevented for k weeks or longer. When emul- sions were applied in the same manner against culiclne mosquitoes, somewhat higher dosages were found necessazy for Aedes and Culex species than for Anopheles quadrimaculatus . Black Flies In the Upper Peninsula of Michigan, Ray Hutson reports that golf players were protected from the black fly Simnlium venustum Say tlirough the application of dusts containing 1 percent of DOT, The ma* terial was applied with a hand dust gun to golf greens and tees at the rate of about 15 pounds per acre. Bushes and shrubs were also dusted liberally. The premises were kept practically free of flies for approximately a week. Deer Flies In preliminary tests in Oregon by C, M. GJullln and D, Mote, dusts and sprays containing DOT were unsatisfactory when used on wet soil that contained larvae and pupae of deer flies (Chrysops spp.). The adult flies emerged from the puparia on the top layer of mud, and thus - 5 - there was no opportunity for them to como Into contact with the in- secticidal treatnent of the soil. » Applications of concentrated emulsions and oils containing DDT to the ears of cattle did not prevent engorgement- of "blood hy the flies on the treated ears. The flies lived ahout 12 hours after engorgement. "» Filter Flies In Wisconsin L. F. Warrick killed adult filter flies (Psychodldae) ■vrith a residual spray (see Houseflles, p. 6 ) containing 2,75 ounces of DDT in a gallon of kerosene, applied at the rate of 1,1 gallons per 1,000 square feet on the side walls of a sewage-filtration plant. As the flies emerged from the scum on the surface of the water, they rested on the treated walls and were killed. The habit of resting on walls near their breeding and feeding places makes filter flies vul- nerable to residual treatments of DDT sprays. Two days after the sludge beds of a sewage disposal plant had been sprayed with 7 ounces of DDT in 50 gallons of kerosene, many dead maggots could be seen in the cracks in the beds, but smaller numbers were also found in the check beds where only kerosene had been used. Five days after treatment the maggots could be found only in the lower 1/2 to 1 inch of sludge, in the DDT- treated area. In the check area numerous maggots were working throughout the entire depth of sludge. Twelve days after treatment no fly larvae could be found in the DiOT- treated area. Few puparia were found, and they were present only near the bottom of the sludge. In the check area, treated with kerosene only, many puparia and active larvae were found and many flies had emerged. The operator of the plant rejKsrted that the filter fly nui- sance in his house and in the laboratory had been greatly relieved, Horn Flies At Dallas, Tex,, E. W, Laake reported 37 tests in which DDT sprays made of emulsions or water-dispersible powders (micronized ma- terials that are easily dissolved in a suitable wetting agent) had been applied to herds of dairy and beef cattle for the control of horn flies (Siphona irritans (L, )), With a dosage of DDT ranging from 0,67 to l»h grams per animal satisfactory control was obtained for 5 to 7 days. When three-fourths as much DDT was used the control was of shorter duration, and when one-half as much DDT was used the re- sults were unsatisfactory. Sprays containing emulsions in xylene or In pine oil, applied at the rate of U or 5 grams of DDT per animal, gave excellent control for l^i- to I8 days. In Kansas, Texas, and Florida a 2,5-percent DDT spray, made of water-dispersible 50-percent DDT, was effectively applied to range and dairy animals •^Tith power sprayers. One application to the backs and bellies of the aniraals in chutes or corrals remained almost completely effective for 10 to 15 days and a second application for 2 to 3 weeks. In general the tests indicated that the period of protection depends upon the quantity of DDT applied to the animal rather than upon the - 6 - volume of the spray or the kind of equipment used. With the methods and materials used, satisfactory control for 10 to 15 days or more vas not obtained with less than k to ^ grams of DDT per animal, S, V. Laake also reported that a herd of 250 purebred Herefords were dipped in a xylene-soluble pine oil emulsion containing 0.12 per- cent of DDT. The herd averaged 14-, 000 flies per animal, but 2 hours after dipping, and for kQ hours, the herd was entirely free of horn flies. Observations on the kth, 6th, 9th, 11th, and l4th days after dipping showed an average infestation per animal of 1,5, 3.8, 3. If, 5.9 (all afternoon observations), and 0.1 (morning observation) flies, respectively. During this period (2 weeks) no reduction of the horn fly infestation on check herds in the neighborhood was observed. Another treatment was made with the same dip Ih days after the first dipping. The two treatments gave almost complete control for at least 2 months, whereas untreated animals on neighboring ranches carried from 50 to 1,000 flies during this period. In Florida W, G-, Bruce reported that effective control of horn flies was obtained for more than 2 weeks with dips containing 0,2 per- cent of DDT, as well as with sprays containing 2 percent of DDT, an emulsion being used in both cases. Houseflies DDT was used effectively in sprays for treating favorable rest- ing places of hooeefliefl (Maeca domestica L,). When the sprayed sur- faces became dry, the toaclc DDT deposits that remained continued to kill flies and other insects that alighted or walked upon them. These deposits were effeotive for several weeks or monthe, depending upon the kind of spray used and the length of time the sprayed surface was e35>osed to direct s\mlight or water. Because this method of applying sprays differs from the direct applications of sprays against insects, the term "residual spray" is employed to differentiate it from a "space spray," the kind of spray ordinarily applied in the air as a fog or mist. The DDT residual sprays found most practical to date are suspensions of 2,5 percent of DDT from water-dispersible powders, 5 percent in kerosene^ or 5-P«rcent emotilBions prepared by diluting concentrates containing 25 percent of DDT, 65 percent of zylene, and 10 percent of Triton I-IOO. Kerosene spray s.--rti in percent of DDT in kerosene (7 02. In 1 gal . ) has been used effectively under a wide variety of conditions during the past 2 years. It has been sprayed on favorable resting places for flies in dairy bams at Beltsville, Md., at several loca- tions in Florida, in South Dakota, and in eastern Montana, It has been applied to walls in dining rooms and on walls and screens of re- sidences in several States, A single treatment at the rate of 1 gal- lon to 1,000 square feet of surface (about 200 mg, of DDT per square foot) was effective throughout the season. Some treatments were 95 percent effective for k months and continued to kill houseflies for 10 months. Where the breeding places were neglected, flies emerged - 7 - faster than they were killed in the treated rooms. This is attributed to the fact that 1 to 1^ hours is required for killing the flies. It is therefore possible for the newly emerged flies to become annoying in treated buildings. Such occurrences emphasize the need for con- trolling the breeding places of houseflies. Horse stalls in Indiana and Florida and dog keimels in Florida sprayed with this solution gave a high degree of protection to man and animals from annoyance by houseflies and also from bites of stable- flies. The use of residual sprajs only about the entrances of kitchens, restaurants, creameries, hospitals, cheese factories, meat-packing establ:',3hments, and a camp for cherry pickers gave considerable con- trol Tor more than 2 months. When the DDT-kerosene spray was applied to 150 square feet of a shaded oorrugated-metal siding of a building between a milk house and a cooling room, it killed flies throughout the season, but the effec- tiveness decreased by the end of the seventh week. In some instances the spraying of unpainted wood, concrete, brick, and plaster surfaces with kerosene containing DDT was not effective in forming a residue for killing flies. It appeared that such walls absorbed the DOT. Kmnlslon sprays. --At Beltsville, tC, L. S. Henderson sprayed concrete bams with 2 percent of DDT in xylene emulsion, at the rate of 200 mg. of DOT per square foot. This treatment provided surfaces vhich killed flies for 1 month. When similar bams were sprayed irith a 1-percent emulsion, at the rate of 125 mg* P©r square foot, the treated surfaces killed flies for 2 weeks and then became less effi- cient. In several practical tests sprays containing 5 percent DOT- xylene emulsions were effective on metal walls and on old painted surfaces, but there was some objection to the white deposits on dark- colored surfaces. Water- dlsperslble powder sprays . — The water-dispersible powders recently developed by different manufacturers are considered suitable for spraying porous walls and ceilings of bams, stalls, and poultry houses. They leave white residues on the treated surfaces, but do not appear objectionable on whitewashed or white-painted walls of out- buildings. In the tests conducted so far the water-dispersible sprays on walls of a porous nature appear equally as efficient as the DOT- kerosene sprays of the same concentrations on smooth surfaces. On concrete walls applications of 100 rag. of DOT per square foot gave excellent control of houseflies throughout the season. Dusts. — Dusts containing 10 percent of DOT, applied with a hand duster in bams Just before the cows were milked, killed the flies present, but there was no noticeable protection a day or two after this treatment. - 8 - Celling streamers, — Streamers made of cloth and treated with a 5- or 20-percent WS emulsion killed flies that alighted on them, but they were not preferred hy the flies as resting places. In dairy "bams in eastejm Montana, when treated strips of cheesecloth were used, there was no noticeable reduction of the housefly population, and it was necessary to resort to other means of control, fl Sandflies Sprays containing 5 percent of DDT in kerosene were applied by M, G, Bruce to screens of residences at New Smyrna Beach, Fla,, for control of sandflies (Culicoides spp.). Numbers of the flies died shortly after they passed through the meshes of the screen and before they were able to take a meal of blood. Protection was obtained also from 10-percent DDT powder applied on the clothing that was worn about salt marshes. The powder probably gave less protection than a spray containing an Insect repellent such as dimethyl phthalate or the radbc- ture used by the armed forces. Dog Flies or Stablef lies Bay -water emulsions of both DDT and DDT residual oil, applied by S, W. Simmons and E. B. Blakeslee as light surface sprays to infesbed marine- grass deposits alcmg the shores of inner bays of northwestern Florida, effectively controlled breeding of the dog fly (Stomoxys} calcitrans L,), also called the stablef ly. The treatments did not penetrate the grass to kill the immature stages, but the adult flies that walked upon the treated surfaces were killed. Plot tests of com- parative toxicity showed DDT to be about four or five times as lethal as the residual oil. When applied to marine-grass deposits at a concentration of 0,5 percent for DDT, or 2.^ to 3 percent for DDT residual oil (contains about 22 percent of ^.'-DDT), at the rate of 2 gallons per 100 square feet, 90 to 95 percent of emerging flies were killed. On in- fested grass treated and subjected to tidal action, 60 percent control was obtained when results were compared with those obtained on a similar untreated plot. The treatment plus the effects of the tide provided 90 percent control of the fly breeding. Uninfested grass treated with these sprays has shown complete protection against in- festation for the period it is susceptible to fly breeding. Approximately kl miles of gra^s distributed along 75 miles of shoreline were treated by E, B. Blakeslee, in cooperation with K. D. Quarterman, with either DDT or a DDT residual oil. A total of 7,5^5 gallons of diluted spray were applied at an average rate of ap- proximately l80 gallons per mile of grass. The observationa surest that new deposits of grass accumulate within 2 weeks, and these should be treated in order to prevent flies from developing in the new accumulations , - 9 - In different localities spra^ applications of emulsions contain - Ing 5 percent or less of DDT to cattle, horses, and dogs did not pro- vide any immediate protection against stable flies. The flies gorged themselves on the treated surfaces, and most of them died within a few hours after feeding. Protection of animals was obtained from treat- ments of walls and ceilings of bains and stables, as described for tests with houseflies. These treatments were equalljr effective for both species of flies. Soldier Flies Sprays containing 5 percent of DDT and dusts containing 10 per- cent of this chemical were applied to pits of latrines and found to be ineffective against larvae of the soldier fly Heirietla llluoenB (L.), Screens treated with the spray killed adult flies that walked over them, Screwworms A smear containing 20 percent of DOT and a dust containing 10 percent of DDT were used by H, E, Parish for treating wounds of 20 sheep Infested with 5-clay-old screwworms (Cochllomyla amerlcana C. end P.), The animals suffered no ill effects, and the average period re- quired for healing was 3^ days. Both the emear and the powder pro- tected the wounds against relnfestation for 21 days. After both treat- ments reinfestation occurred In half the wounds, whereas In sheep treated with smear 62 (containing dlphenylamlne) only hO percent of the wounds were relnfested, DDT therefore appears to be somewhat less effective than smear 62, the recommended treatment for protecting wounds of animals, American Dog Tick Because the American dog tick (Dermacentor variabilis (Say)) transmits the eastern strain of spotted fever. It has been desirable to develop a treatment that C€in be used on vegetation to free the pre- mises of residences, parks, and canrp sites of these ticks, Emulslans containing 0.5 percent of DIXT and 2.5 percent of soluble pin© oil gave a high kill of these ticks. The applications were made at the rate of about 3 pounds of DOT per acre. Experiments with dusts containing DOT have not always been aucceasfxil. Dips and dusts for the infested animals have not been so satisfactory as the standrad dips and the ground derrls or cube powders containing 5 percent of rotenone. Brown Dog Tick A dwelling at St, Andrews, Fla,, heavily infested with all stages of the brown dog tick (Rhlpl cephalus semgulneus (Latr,)) was treated with DOT by E. B, Blakeslee. About l/2 pound "of powder containing 10 percent of DOT was applied beneath and behind the baseboards of all rooms. The dog In the house was treated with 15 grams (about l/2 tea- spoonful) of the powder on four occasions. There mre no apparent 111 - 10 - effects upon the animal or the residents, and within 2 to 3 montiis the infestation was brought under complete control. For controllin^^j light or moderate infestations, as little as h ounces of the lO-percent powder was found to be sufficient to give control of the infestation when applied in a small apartment where one dog was kept. One thorough treatment of a dog hospital brought freedom from brown dog ticks for almost a year. Sprays containing 5 percent of DDT were just as effec- tive as powders for treating baseboard crevices. Fowl Ticks Poultry houses infested with the fowl tick (Argas miniatus Koch) were sucessfully treated by H. E, Parish with a residual spray con- taining 5 percent of DDT in kerosene. The treatment was applied to the perch poles end to cracks, crevices, and other hiding places of the ticks. For 3 months following treatment no living ticks could be found. On account of the long life of this tick, the test will be observed for any reoccurrences of the infestation. Gulf Coast Tick The bite of the Gulf Coast tick (Amblyomma maculatum Koch) is an important cause of screwwocrm attack on livestock in the coastal areas of the Southern States. From about the first of August until the latter part of October approximately 85 percent of all screwworra in- festations occur in injuries produced by this tick, and there is need for a treatment that will remain effective for 10 weeks or more. In Florida tests were made by W, G, Bruce and A. L, Snith to determine the effectiveness of a ta^eatment containing 5 percent of DiDT in a nondrying adhesive, which is a form of synthetic rubber, and dibutyl phthalate. This treatment had been used against this tick by E, B, Blakeslee in Florida, Dish-mop and paint-brush methods of application were fairly satisfactory, but the use of the bare hand was faster and afforded a more complete coverage of the ears of long-haired cattle. On 18 head of cattle that were wild and difficult to handle, it was almost im- possible to obtain complete coverage of the ears, and 20 days after treatment only about 20 percent of the ticks on these animals were killed. In 7 tests made on as many ranches, representing a total of 250 head of cattle, no screwworms developed in the ears of any of the treated animals, whereas many ticks were present on untreated cattle ranging in the same pastures. In Edna and Port Lavaca, Tex,, the treatment was applied by H. E, Parish and C. S, Rude in several experiments. On one ranch 592 head of mixed cattle having an average infestation of k,k9 ticks per ear were treated. At the end of 2 weeks the number was reduced to 0,5 tick per ear and only 10 percent of the animals required another treatment. Four weeks later there were 1,85 ticks per ear and one- third of the animals needed another treatment. The untreated animals on the ranch had 5,95 ticks per ear 2 weeks after the treating date, and Ih ticks per ear at the end of k weeks. -li- on another ranch 778 head of mixed cattle averaged h,6 tlcke per oar vhen treated, and 2 weeks later averaged 0.2 tick per ear. Dur- ing the same period a treatment of 35 horses reduced the numher of ticks per ear from 3.^ to 0.5. Lone Star Tick The clothing of several volunteer workmen In woods In southem Georgia was treated by C. U. Smith with a 10-percent DDT powder or a 5-percent DDT emulsion and worn hy them on a raage Infested with the lone star tick (ABblyonma anerlcanum (L) ) . The treatments did. not prevent attachments and engorgements of the ticks. In prellmjLnary tests a 5-peroent DDT powder applied to grass land at the rate of 3 pounds per acre killed all stages of this tick, and 1 pound of WS per acre applied in a pine- oil emulsion was equally effective* Dips with 1 percent of DDT in a pine- oil emulsion showed some promise when used for dipping Infested dogs, but did not kill the larvae that were attached. Relapsing Fever Tick Specimens of the tick that; carries relapsing fever, Omithodoros tnrlcata (Dog^s), were treated in the laboratory with spray emulsions of DOT famished by the Bureau to Neal M. Randolph, of the Texas State Board of Health. Sprays containing 10 percent of DOT killed 90 percent of the ticks, when applied as a direct spray, the mortality ooenrrlng gradually after 6 days and being coBKplete 9 days after treatment. A 1- percent DOT spray applied to the inside of cages con^ talning no debris or litter gradually killed 90 percent of the ticks at the end of 30 days. Sprays applied to clay floors in the cages killed about 20 percent of the ticks. These findings suggest that DOT sprays may kill many of the ticks in caves. Inside of dry caves, however, under natural conditions, such a treatment could not be ex- pected to eradicate an infestation. Winter Horse Tick A wash used by H. £• Parish and C. S. Rude on 35 horses infested with the winter horse tick (Dermacentor nigrolineatus (Pack. ) ) con^ talned 0.9 percent of IDT in a soluble-pine- oil emulsion. It killed all the ticks on the horses and protected them from relnf estatlon for about 60 days. There was no apparent injury to any Of the horses; on the contrary there appeared to be an Improvement in the skin and hair. Similar washes with less DOT did not kill all the ticks present. Srtemal Parasites of Rats At Savannah, Ga., H. K. Gouok treated four poultry-produce stores for control of fleas, mites, and lice on rats. As soon as some rats were caught from these premises, they were killed and placed in bags and fumigated. The parasites were then collected and retcdned for - 12 - Identification. Specimens were identified as Nosopayllus fasclatus (Bosc,)^ LlponysBus bacoti (Hirst), Xenopsylla cheopts (RothBcIi. ). Ctenopayllus segnls (SchCTi. ), Echidnophaga gallinacea (Westw,), Laelaps havailensts (Ewg. ) , and Poljrplax spinulosa (Buna. ) , Store A vas treated by means of a dust gun, using 3 3/U pounds of 10-percent DDT powder; store B was treated with 5 l/k pounds of DDT; and store C was treated by using 2h paper cylinders each contain- ing 25 grams of I3ET. Four days after treatment there was a decrease of 90 percent in fleas, 100 percent in mites, and 73 percent in lice in store A; and a decrease of 100 percent in fleas and $2 percent in lice in store B, all as compared with the number of insects on rats before treatment. In store D (untreated) there was an increase of 2 percent in fleas, 65 percent in mites, and a decrease of tS percent in lice. This study suggests that IGDT dusts are promlsiag as treatments for control of external parasites of rats. Further observations are being meide to determine the period of effectiveness of the treatments. Ants Ant hills built by one species of Tapinoma between the briclcs of a drive-way and between stones of a terrace were promptly abandoned when I3DT powder was placed on them. The treatments were made in June and the nests remained unoccupied for the remainder of the season. During July and September numerous ant colonies were treated with 10 percent of DDT in pyrophyllite, A small amount of the powder placed around the entrance holes of the nests of fire ants (Solenopsls gemlnata (F.)) resulted in a ccraplete disappearance of the ants. TThen undiluted technical DDT was placed in very small amounts about the surface of two large nests of carpenter ants (Camponotus sp«), in soil against a house foundation, all the ants disappeared. A smaH aiaoimt of a 10-percent DIT-pyrophyllite powder was dusted over trails of the crazy ant (Paratrechlna lonAlcomip (Latr,)), and a spray containing 5 percent of DDT was applied to floor areas infested wi-Ui this species; in both cases the ants disappeared for more than 3 nonths. In residences sprays containing 5 percent of DDT in kerosene killed all ants hit with the spray, but some of these treatoents gave only temporary relief. The treatments were Ineffective against ants that did not make trails into the buildings because it was iciposaible to anticipate their route of travel and thus treat the proper places. They were more effective "vrhen applied to ant trails but did not pre- vent all the ants from foraging in kitchens. Bedbugs Kerosene sprays contalnlrtg 5 percent of DDT have been used ex- tensively on beds of Army and Navy personnel for control of bedbugs. Recently a large number of tests were undertaken, in cooperation with the National Pest Control Association, in about 20 cities of the United States to determine the efficacy of the treatments for use in j ^ - 13 - ^ apartmen,)tB, hotels, and residences. Deodorlzed-kerosene sprays con- taining/LO percent of DDT in pjrrophylLite were furnished to pest con- trol oj/erators, together with suggestions on methods of application. Mattresses, pillows, bedsprings, and crevices about the beds were treated with the spray or the duet. PVom these tests it was learned that double beds could be treated efi'ectively with 3 liquid ounces of spray or with 2 ounces of the powder. The treatments persisted long enough to kill the bugs that came out of hiding to obtain a meal of blood. In theaters and in railroad cars, on seats that were Infested with bedbugs, sprays were apparently used with results equal to those obtained on bedding. Cockroaches ExperiioentB vero conducted against the Aioerlcaa cockroacli (Perl- •planeta ajnerlcana (L,)), tbe Qenann cockroach (Blattella germanlca (L,)), and the hrown-handed roach (Supella supeHect Ilium, (Serv . ) } in cooperation with goremment agencies and peat control operators in- terested in the control of cockroaches in clTllian food estahlishments and kitchens. The experiioents vere carried out under rarious condi- tions with 5 percent of DDT in kerosene or emulsions, or with 10 per- cent of DDT in pyrophyllite . It appeared that any one of the treat- ments was as effective as dodium fluoride when applied hy trained per- sons to the proper places. Within an hour or 2 after treatment some dead roaches were found and many Hying ones showed the effects of the treatment, and after ahout 7 days the populations of the roaches were greatly reduced. In the South, where roaches often develop outside of huildlngs and migrate into kitchens, and also to prevent importation of new roaches in grocery or other deliveries, it was iB5)ortant to main- tain a residual treatment in favorahle places to kill the roax^hes and to keep new ones from 'becoming estahlished. Because cockroaches like to walk upside down l^neath refrigerators, table tops, and shelves, a spray was used in conjunction with any diist treatments made in kitch- ens. Sprays were used to good advantage in cuphoard drawers and other partly closed spaces against the German roach, or in reuiios and simi- lar places for the hrown-handed roach. Kerosene sprays should he used only in places where they offer no fire hazard. Fleas In experiments made by A. W. Lindquist in Florida and C. N. Smith in Georgia, powders containing 10 percent of DDT in pyrophyllite applied at the rate of about 10 grams (l/3 teaepoonful) for an average- size dog killed the flea C tenocephal Ides canls (Curt.) within 10 to 15 minutes to a few hours. The treatmwits temporarily stimulated the fleas to become active on the animal, and some dogs continued to scratch for about an hour. A single treatment protected the animals from further infestations for k to J days. These treatments were supple- mented by dusting or spraying of Infested bedding and premises at the rate of 1 pound of a 5-percent DDT powder or l/2 gallon of a spray con- taining 5 percent of DDT per 1,000 square feet. The dusts containing 1 percent of DDT and the pine-oil emulsions containing 0.2 percent of DDT were used eatlefactorily on Lawns infested with fleas, but oil sprays often burned the grass. Single treatments of dogs and kennels yielded satisfactory control of fleas, including the sticktight flea, (Echidnophaga gallinacea (Westw.)). Cats often became sick from lick- ing the powder from the hair, and some of them ingested enongh DDT to cause their death. Wasps and Hornets Colonies of wasps were destroyed by Helen Sellers in many places in Washington, D. C, and vicinity, with applications of a 10-percent DDT-pyrophyllite dust into the entrance holes of the nests. Treatment of a nest of Vespula maculifrons (Buyss.) established beneath a rear pdrch between r floor and ceiling destroyed the colony. Where yellow Jackets (Vespa sp.) occupied a gourd that had been used as a wren's nest, a dust treatment freed the gourd of the pests within 2k hours. A similar treatment of two nests of Vespula diabollca (Sauss.) was in- effective. A white-faced hornet's nest over the entrance to a garage, treat- ed by the same method, was found to be abandoned the following morning. Wasps (Polistes ep.) nesting beneath a doorstep in a cellar area- J and near an electric-light fixture on a porch, were dusted with this powder with excellent results. No Polistes were seen after 12 hours. It appears that a 10-percent DDT-pyrophyllite mixture will prove useful for control of wasps' and hornets' nests.