Recent rulings by the Food and Drug Administration make it more imperative than ever that practitioners use, sell, and recommend proper insecticides for the control of ectoparasites. Very few of the commonly used insecticides have a tolerance established by the FDA in meat and dairy products

Raum, Earle S.

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Recent rulings by the Food and Drug Administration make it more imperative than ever that practitioners use, sell, and recommend proper insecticides for the control of ectoparasites. Very few of the commonly used insecticides have a tolerance established by the FDA in meat and dairy products.</p

Raum, Earle

Digital Repository @ Iowa State University (ISU)

Large AnimalEctoparasite ControlEarle S. RanD, Ph.D.RECENT RULINGS by the Food andDrug Administration make it moreimperative than ever that practitionersuse, sell, and recommend proper insecti-cides for the control of ectoparasites. Veryfew of the commonly used insecticideshave a tolerance established by the FDAin meat and dairy products.What is a tolerance? It is the an10untof material permissible in the food prod-uct under existing regulations. Insecti-cides actually fall into three categories:<'Zero tolerancen (none permissible), "es-tablished tolerance" (small amount per-missible), and "none requiredn •Amo11g the facts utilized by the FDA inits rulings on a given insecticide we find:( 1) toxicity of the particular insecticideand its metabolites to man, (2) storageof the insecticide in the human body andin what forms it is stored, (3) residualamounts in the treated animal's n1eat ormilk after use of the insecticide, (4 )length of tin1e the residue remains in thetreated animal's products.Many editorials have been written con-cerning the pro's and con's of the FDAand its rulings, but the fact remains thatthis organization is charged by law withprotecting the nation's food supply fromdeleterious substances. Insecticides aremeant to kill. True, they are meant to killinsects, but with indiscrimi11ate use theycan be hazardous to man and otherforms of life.You, as a practicing veteri11arian, area leader in your community. Your wordsare taken as "gospeln • You have, therefore,Dr. Raun is an associate professor in the De-pal'1tment of Entomology and Wild Life, IowaState University.Issue 2, 1960a responsibility to your clients and yourneighbors to give the RIGHT answerwhen your advice is asked in either aprofessional or a non-professional way,Particularly is this true in areas ofknowledge in which you should be up todate. Insecticides and their use on live-stock are in that area of knowledge.This article will attempt to bring you upto date 011 the recommendations for largeanimal ectoparasite control, as of the mo-ment. Continuing research is uncovering11ew facts, however, and recommenda-,tions and tolerances are continuallychanging in the light of these new facts.The Insect Information Letter, which youreceive periodically from the Iowa StateUniversity Department of Zoology andEntomology, will help you stay up to date.Iowa State University recommendationstake into account a number of facts; ef-fectiveness of a material, FDA rulings,toxicity, ease of use, availability of a ma-terial, and cost. You may find that ISUrecommendations differ slightly fromthose of surrounding states. Differences:in cost and availability will lar~ely ac~count for these.CATTLE ECTOPARASITES:Cattle grubs: The control of cattle grubs',has received a big boost from the dfscov-,ery of systemic insecticides. Grub controlis now possible to achieve before the d'am-,age to the hide and loin area occurs. The'one systemic material which farmers in~Iowa will find most usable, at the present~time, is Co-Ral (Chemagro Chern. Corp."Kansas City, Mo.), a polyphosphate. Ap-,plied as a spray as soon after the end of'the fly season as possible, it is absorbed',8~through the skin and systemically killsthe young grubs wherever they are in thea11in1al's body. Advantages of Co-Ral in-clude 90 to 99 percent control of grubs,fall application before cold weather, con-trol with one application, and excellentlouse control as a bonus. Many farmers,after using Co-Ral for a season, havestated that the louse control alone isworth the extra cost. Disadvantages in-clude a material cost of 50 to 85 cents perhead. Also, the material should not beused on lactating dairy cows because itappears in the milk.Mix Co-Ral at the rate of 4 pounds ofthe 25 percent wettable powder in each25 gallons of water. One gallon will treatone to two head, depending on the sizeof the animal. Spraying equipment pres-sures should approximate 250 pounds ifpossible. If this high pressure equipme11tis 110t available, 80 to 100 pounds pres-sure will be adequate provided ~ pound ofhousehold detergent is added to each 25gallons of spray.For grub control on dairy cattle, rote-none dusts applied every 30 days duringthe time the grubs are present in the backsof the cattle will do an adequate job. Sucha treatme11t should be a must in area con-trol programs where farmers have agreedto treat all cattle in a given area to elimi-nate "gadding" of cattle caused by theadult grub flies during the summer.Cattle lice: As you know, cattle may beinfested with either the blood, sucking orthe chewing lice. Either type may be con-trolled by the cattle grub spray of Co-Raldescribed above. Other materials ap-proved for spray-use on beef cattle include0.5% toxaphene, 0.5% methoxychlor,0.5% malathion, and 0.3% Korlan (DowChern. Co., Midland, Mich.). None ofthese materials should be used on lactat-ing dairy cows, nor should they be usedon cattle to be slaughtered within a 60-day period.Many farmers are going to the use ofcattle oilers and back-rubbers for the con-trol of cattle lice. These do a good job ofkeeping louse populations below economiclevels at a reduced labor cost. One thingto keep in mind, however, any automatic90curryi11g device or back rubber which af-fords the animal a solid, sharp-edged rub-bing surface is likely to crush any cattlegrubs present in the animal's back, andmay cause an anaphylactic shock, or ab-scess formation. We feel that back-rubbersof this type should be discouraged duringthe cattle grub season.Approved materials for use in back-rub-ber applications for louse control include5% toxaphene, 5% methoxychlor, 5%DDT, 3% malathion, and 1.3% Korlan.Controlling the louse populations ondairy cattle requires the use of rotenonedusts or pyrethrins sprays, applied twicenine days apart. None of the materialsother than these two, can be used on lac-tating cows due to the appearance of thematerial in the milk.Cattle fly control: We have tradition-ally had orily two important flies feedingon cattle during the summer months, butmay be threatened by a third species thiscoming year. The two old acquaintancesare the stable fly and the horn fly. Thethreat from the east is the face fly, Muscaautumnalis.The horn fly is the first to appear onour cattle each spring. They cluster onthe backs of the cattle, feeding and rest-i11g alternately. Untreated beef herdssometimes support a horn fly populationof more than 1000 per head.The stable fly sucks blood from theanimal, requiring about two minutes toobtain a blood meal, and then it flies offto rest on fences, barn walls, or vegeta-tion. At one time you may be able tocount as many as 100 stable flies perhead on untreated beef herds. From thestandpoint of damage, numbers, and dis-ease carrying, the stable fly is by farthe most serious pest.The face fly is not a blood feeder. Itfeeds on the mucous secretions aroundthe eyes, nostrils, and other body open-ings. Its damages are caused by annoy-ance and perhaps its ability to carry dis-ease.The control of flies on animals differsconsiderably between beef and dairyherds. Beef cattle on pasture will beprotected from the horn fly through theIowa State University Veterinarianuse of the back-rubber, utilizing one of thesame chemicals des-cribed under lousecontrol. Or the louse control sprays maybe used for horn fly control, applying oneof them every two to three weeks duringthe summer months. These treatmentswill not do an adequate job of controllingthe stable fly, however.Controlling flies on cattle in the feedlot is a different matter. Stable flies be-come even more important in and aroundthe feed lot than they are on pastured cat-tle. The same treatment for the animalscan be used, but residual sprays on thefences, undersides of feed bunks, barnwalls, and even surrounding vegetationare required for control of the stable fiy.Chemicals for these residual treatmentsare diazinon, malathion, or Korlan. Dia-zinon will be effective for the longest per-iod of time, lasting about two weeks inopen areas.Dairy cattle fly control is limited to thepyrethrin-type fly sprays applied to theanimals every day. This application willdo an excellent job of controlling all typesof biting flies on the cows. There is fed-eral approval for the use of methoxychlormalathion dust on the backs and shouldersof dairy cattle, but this treatment will con-trol only the horn fly and not the more inl-portant stable fly. The insecticides listedabove for residual area treatments maybe used in the dairy barn as well as otherlivestock buildings.The control of face flies apparently re-quires the daily use of the pyrethrin sprayson the heads of the animals. This meansthat beef cattle are going to continue tobe plagued by this pest. Dairy cows willbe protected by the daily sprays if particu-lar attention is paid to the "face" of thecow.Swine EctoparasitesMange and lice: The most importantpests of swine are the various mange-causing mites, and the blood-feeding louse.We have been advocating a preventivetreatment for these pests. In one group ofsows, which showed no signs of mange orlice and which had received no chemicaltreatment for six months, an examinationrevealed the presence of Sarcoptes scabieiin the ears of almost 100 per cent of them.Issue 2, 1960This meallS possible transmission of themites to their litters.It is our conviction that sows shouldbe treated whether or not symptoms ofmange or pediculosis are present. Thetreatment should be done either about 30days before farrowing, or as the sow isbeing put into the farrowing stall. Lin-dane, (gamma Benzene Hexachoride,U.S.P.), as a 0.05~o spray, applied at thistime, will control both the mites and thelice, preventing the infestations on thepigs. The same chemical added to thewash water as the sow goes into the stallalso seems to do an adequate job.Sheep EctoparasitesSheep scab: The problem with "wet111ange", caused by the mite Psoroptes equivar. ovis, continues to be serious here inIowa. Many farm flocks 11ave required thequarantine-dip activities. Much of theproblem could be prevented if farmerswould be certain that any new animalsthey obtain are dipped before they arebrought to the farm. This applies to ani-mals from within Iowa as well as fromother states, and to animals bought notonly in the sale barn but fronl othersources.Approved dips now may contain eitherlindane or toxaphene. Be sure you reportany sheep scab cases that you diagnoseto the State Veterinarian's office. Eventhough you are afraid you will lose aclient by such reporting, the livestock in-dustry of your area a11d the state willbenefit from the supervised quarantineand dipping which is required of suchcases.Sheep keds (ticks): Melophagus ovinus,the wingless, blood-sucking fly of sheep,is vvidespread. It can cause serious lossesto young lambs. It reduces the quantityand quality of wool from the ewes. Thereis no reason it should continue as wide-spread as it is, with the many moderninsecticides which will kill it. An annualdusting, spraying, or dipping with DDT,toxaphene, rotenone, malathion, Korlan,or Co-Ral will do the job. Shearing timeaffords an excellent opportunity for thiscontrol program.-End91

Large Animal Ectoparasite Control

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Large Animal Ectoparasite Control

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