Division of Agricultural Sciences and Natural Resources • Oklahoma State University

VTMD-7000

Beef Cattle Ectoparasites

Thebeefcattle industry inOklahomalosesmillionsofdollars annually due to external parasites. These lossesresultfromreducedperformanceduetobloodloss,irritationandannoyance.Indirectly,diseasesaffectingcattle,dogs,andhumansmaybetransmittedbyexternalparasitesofbeefcattle. Flies,ticks,andlicearemajorpestsofcattle.Severalspecieswithineachgroupofparasitesexistandbecauseoftheirseasonaloccurrence,externalparasitecontrolisayearroundconsideration.Properidentificationisnecessaryfordeterminingtheappropriatetreatments.Controlshouldbebasedoneconomicthresholdswhenpossible.Timelyappli-cationsofrecommendedinsecticidesshouldimprovecontrolefforts.Somepestproblemsmayalsobereducedbyavoiding:1)theintroductionofinfestedanimalsintotheherd;2)poornutrition;3)overcrowding;4)sloppyfeedingandwateringofanimals;and5)inadequatemanurehandling.Eliminationoffly-breedingsitesaroundfeedlotsorpremisesreducesfilthflies,(housefliesandstableflies). Whentreatmentbecomesnecessary,insecticidesmaybeapplieddirectly tocattleassprays,dusts,pour-ons,orself-treatmentdevices.Theymaybegivenorallyorsubcu-taneouslyinjected,administeredasabolus,fedastreatedfeedsormineralblocks,orinself-treatmentdevicessuchasbackrubbers,dustbags,oilersoreartags.Flypopulationsaroundlivestockpremisesaretreatedwithresidualsprays,mists,andbaits.TheOSUExtensionAgents’HandbookofInsect,PlantDisease,andWeedControlisupdatedannuallyandhasalistofrecommendedinsecticidesandmanagementpracticesforthevariouspestsdiscussedinthispublication.

Pasture Flies Hornfliesarethemostnoticeableandabundantfliesonpasturedcattle.Thesesmallblood-suckingfliesarecommonfromAprilthroughOctober.Leftuncontrolledtheymayreachseveralthousandperhead.Adultsare3/16”inlengthandfeedintermittentlyonthebodiesofcattleandspendmostoftheirtimerestingonthebacksofcattle(Figure1).Femaleslayeggsinfreshcowmanure,andinhotweatherthehornflycancompleteitslifecyclefromeggtoadultin10days.Thisrapiddevelopmentallowshornflypopulationstoexplodeinashort timeandcontributestotheresistanceproblemas-

sociatedwithhornflies.Emerginghornfliesmaytravel10milessearchingforcattle,inwhichcase,draggingpasturesmaybeaquestionablepractice. Control of horn flies should begin when 100 flies perhead are observed. Researchers have shown that 15 to30lbs.ofextragainincalvesisachievedoverthesummerwhenhornfliesarecontrolled.Eartagscontinuetoprovideaconvenientmethodofhornflycontrol.However,resistanceacrossthestatevarieswithpastusageofeartagscontainingpyrethroids.Producersshouldrotatefromorganophosphateeartagsafterthreeormoreyearstoaprogramusingsprays,backrubbers,dustbagsorusepyrethroideartags.Donotuseeartagscontainingpyrethroidsformorethanoneyear.Alternatingcontrolprocedureswillprovidethebestlong-termhornflycontrol. Thestablefly,normallyapestaroundanimalpremises,hasbecomeaproblemonpasturedcattleinthelatespringandearlysummerinrecentyears.Thisflyis1/4”inlengthandbothsexesarefiercebiters.Thesefliesconcentrateonthelegsandbellies,andcattleoftenstandinwaterforhourstogetrelief.Thesuggestedeconomicthresholdisfivefliesper leg(Figure2). Under theseconditions treatmentmaybeeconomicallysound.Thoroughsoakingoffeetandlegswithasprayisrequiredforgoodcontrol.Persistenceofaninsecticideisshort-livedwhenanimalswadeinwaterortallgrass.Self-treatmentdevices,eartags,orpour-onsseldomgiveeffectivecontrolofstableflies. Horsefliesarelargeandrangeinsizefrom3/8”tooveraninchinlengthdependingonthespecies(Figure3).Thefemaleflyfeedsintermittentlyandfrequently.Thisfeedinghabitmakessomehorsefliesagoodvectorofanaplasmo-sis.ThemostcommonhorseflyinnorthcentralOklahoma,Tabanus abactor,wasconfirmedtobeamechanicalvectorofanaplasmosismorethan40yearsago.Inmosthorseflyspecies,onlyonegenerationoccursperyear.Mostspeciesarenumerousinbrushandtree-coveredpasturesespeciallynearcreekbottoms.Thelarvaedevelopinwetsoilsormoistsoilsinheavilywoodedareas.Treatingthesoilforthelarvaestageisimpractical.Forspecieswithpreferredfeedingsitesalongthebacksofanimals,backrubbersprovidesomecontrolofhorseflies.However,horseflyspeciesfeedonthelegsandundersidesandanycontrolisoftenpooratbest. Unlike thepreviousmentionedflies, facefliesarenotbloodsuckers.Thislargeflyis5/16”inlengthandresemblesthehousefly.Itfeedsonfloweringplantsaswellastears,

RobertW.BarkerProfessorofEntomology

BillStaceyNEDistrictExtensionDirector

RussellWrightProfessorofEntomology/Dept.Head

OklahomaCooperativeExtensionFactSheetsarealsoavailableonourwebsiteat:

http://osufacts.okstate.edu

Oklahoma Cooperative Extension Service

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Figure 1. Horn flies on back of cow.

Figure 2. Stable flies as they normally appear on legs of cattle.

Figure 3. A horse fly with horn flies on cattle.

saliva,mucus,andbloodoozingfromanimals.Whileresearchhasnotshownproductionlossesfromthedirecteffectoffacefly nuisance, it has been demonstrated that face flies areimportant inspreadingMoraxella bovis, thebacteriumthatcausespinkeyeincattle.FacefliesareactivefromMarchthroughOctoberandaremostprevalentafterJune.LargenumbersoffaceflieshavebeenreportedinpreviousyearsfromNortheasternOklahoma,butrecentlypopulationshavebeenverylow.Duringheavyoutbreaks,producersshouldconsidercontrollingthispest,especiallyifpinkeyeisacom-monproblem.

Anotherflythatistroublesometocattleistheheelfly.Thispestisaboutthesizeofahoneybee.Heelflieslayeggsoncattleinthespringandearlysummerthathatchintolarvaethattunnelthroughtheskin.Animalsbeingchasedbyheelfliesoftenexhibituncontrolledfearthatcausesthemtorunwildlywiththeirtailshighintheair.Sprayingduringthistimemightprovidesomeshort-termrelief.Controlofthispestisusuallydirectedatthelarvalstageorgrub.Cattleshouldbetreatedforgrubsaftertheheelflyseasonbutatleastsixweeksbeforegrubsappearintheback.InOklahoma,October1shouldbethecutoffdateforgrubtreatment.Treatmentwithanyofthenewmaterialslistedforcontrolofintestinalwormswillalsocontrolthelarvalstageofcattlegrubs.

Premise Flies Fliesthatmostoftenoccuraroundanimalpremisesarethehouseflyandthestablefly.Flypopulationsmayreachextremelyhighnumbersaroundfarmbuildingswherefeedandanimalsarelocated. Thehousefly isacommonpestreadilyrecognizedbymosteveryone.Itisadullgraywithfourstripesbehindtheheadandhasapalegraytocreamcoloredabdomen.Itisabout5/16”inlengthwithsponging-suckingmouthpartsandmayspreaddiseasefromanimaltoanimalorfrommanuretofeed.Houseflylarvaedevelopinfreshmanure.Eggtoadultdevelopmentmayrequireaslittleas8daysforcompletion. Stable flies may become numerous around premisesbecause femalesdeposit eggsonmoist decayingorganicmatter.Spilledfeed,wethay,andstrawmixedwithmanuremakeexcellentbreedingsitesforthestablefly.Eggtoadultdevelopmentrequiresthreetofourweeks. Premiseflycontrolshouldbeginwithagoodsanitationprogram.Ensuregooddrainageofconfinementareas.Re-movemanureregularlyandcleanaroundfeedingareastoeliminatebreedingsites.Keepweedsundercontrolaroundthesitetofurtherreduceflynumbers. Several species of parasitic wasps are commerciallyavailable.ResearchindicatesthatsomespeciesofparasiticwaspshavebeenverysuccessfulincontrollinghousefliesinconfinedpoultryhousesintheeastandinCalifornia.Research

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Figure 4. Lone star tick (male, female, and nymph from left to right).

Figure 5. Gulf Coast tick (female, male, and nymph from left to right).

inKansasandNebraskahasshownthatparasiticwaspsarenotverysuccessfularoundfeedlots.Withoutgoodsanitation,controlofhousefliesandstableflieswillbepoorwithparasiticwasps.Also,colonyraisedparasiticwaspsmaynotdowellwhenintroducedintostressfulclimaticconditionsthatoftenprevailinOklahoma. Diatomaceousearthismarketedforflycontrol.However,littleornoflycontrolwillbeachievedbyusingdiatomaceousearthasafeedadditive,aerosol,dustbag,handdust,orotherapplicationmeasure.Untilscientificdatasuggestsotherwise,itisnotarecommendedpracticetousediatomaceousearthforflycontrol. Electrocuterlighttrapsaremarketedforflycontrol.Thelighttrapsthat“zap”insectsmaybehelpfulintight,enclosedareas, especially indoors with good sanitation. However,outdooruseofthesetrapsdoesnoteffectivelyreducenum-bers. Ultrasonicdevicesaremarketedforflycontrolalso.Ultra-highfrequencysoundwavesgeneratedbythesedevicessup-posedlydisruptliving,mating,andsurvivalofpests.However,researchhasnotbeenabletodemonstrateeffectivecontrolusingthesedevices.

Lice FourspeciesofliceoccuroncattleinOklahoma.Threespecies are sucking lice while the fourth is a biting louse.Suckingliceconsistoftheshortnosedcattlelouse,longnosedcattlelouse,andthelittlebluelouse.Thefourthspeciesiscommonlyreferredtoasthecattlebitinglouse.Suckinglicearemoreimportantfromaneconomicstandpoint. Licespendtheirentirelifecycleontheirhost.Thelifecyclerequiresthreetofourweeksduringcoldweather.Carrieranimals intheherdseemtoharbor infestationsthroughouttheyear.Lownumbersexistduringwarmmonths,butwiththeonsetofcoolertemperatureshighnumberssoondevelop.Tenormorelicepersquareinchhavesignificantlyreducedweightgainsincattlewhilelightinfestationsdidnot. Liceshouldbecontrolledinlatefallratherthanwaitinguntilspringwhenobvioussymptomsdevelop.Herdswithahistoryofspringtimeliceproblemsshouldreceiveapreventivetreatmentinthefall.Introducingnewcattleintotheherdmayspreadlice.Inspectcattlebypartingthehairandexaminingtheskinforlice.Iftwoormorelicearefoundperfour-inchareaexamined,treatmentshouldfollow.Ringwormissometimesmistakenforliceinfestations.Ifcattleappearlousyafterlicetreatments,ringwormmaybeinvolved.

Ticks SeveralspeciesofticksattackcattleinOklahoma.Thewintertickisaone-hostspeciesthatfeedsprimarilyonlargehoofedanimals. Itcanbeasevereproblemoncattleandhorses in some areas. Male ticks are effective vectors ofanaplasmosisbecausetheyoftenareremovedfromahostthrough grooming and may attach to another host, thusspreadingtheanaplasmosispathogen.LarvaeattackhostanimalsfromearlyOctoberthroughApril,molttonymphsonthehost,feedandthenmolttotheadultstagewhilestillonthehost.Bothmalesandfemalestakeabloodmeal,mate,andthentheengorgedfemaledropstothegroundandlayseggs.TickpopulationsonthehostpeakbetweenlateOctoberandmid-February.

Theblack-leggedtickisathree-hostspeciesthatismostabundantintheeasternone-halfofOklahoma.Thelarvaefeedonlizards,birds,androdents,whiletheadultsfeedprimarilyoncattle,horses,deer,dogs,cats,andhumans.TheadultactivitybeginsinearlyOctoberandcontinuesintoApril. Thelonestartick(Figure4) isthemostabundanttickspeciesintheeasternone-halfofthestate.AlllifestagesofthistickattackcattleandothermammalsandcanbeaseverepestfromMarchuntilAugust. The Gulf Coast tick (Figure 5) occurs in the easternone-halfofOklahoma,intoKansas,Missouri,Arkansas,andTexas.Larvaeandnymphsattackrodentsandbirds,whiletheadultistheonlylifestagethatfeedsoncattle,specificallyontheears.Adulttickfeedingcausesdamagetotheearsofcattle,commonlyreferredtoas“gotchear,”whichreducesthemarketvalueofananimal.Recently,theGulfCoasttickhasbeenshowntobeanintermediatehostforaprotozoanparasiteofdogsandothercanines.Themodeoftransmis-sionisthroughoralingestionofaninfectedadulttick.Thedisease, hepatozonosis, is a very debilitating and painfulcondition.Dogsusedforworkingcattleinareaswhereticksoccurcouldbeatrisk. TheAmericandogtickoccursthroughoutOklahomaandwilloccasionallyinfestcattle.Thistickhasbeenincriminatedasavectorofanaplasmosisandthusisanimportantspe-cies. Thespinoseeartickisaone-hostsofttickspeciesthatfeedsdeepintheexternalearcanalofcattleandmanyothermammals.LarvaeattackhostsinMarchandmayfeed40to270daysbeforedroppingfromthehostasanengorgednymph.Theadultofthistickdoesnotfeedandisrarelyseen.

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Tickcontrolisachievedbyvegetativemanagement(thereductionofunderbrushinsomecases)andtheuseofvari-ousinsecticides.MostoftheeartagsforhornflycontrolwillcontrolorpreventinfestationsofGulfCoastticksorspinoseearticks,butthepyrethroidtagsarethemosteffective.Inordertobemosteffective,tagsshouldbeplacedineachear

bymid-Marchtopreventinitialinfestations.Selecteartagsbased on label instructions for control of these ear ticks.Eartagswillnotcontrollonestarticksoranytickthatfeedsovertheentirebody.Formoreinformationonticks,refertoFactSheetVTMD-7001,“CommonTicksofOklahomaandTick-BorneDiseases.”

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IssuedinfurtheranceofCooperativeExtensionwork,actsofMay8andJune30,1914,incooperationwiththeU.S.DepartmentofAgriculture,RobertE.Whitson,DirectorofCooperativeExten-sionService,OklahomaStateUniversity,Stillwater,Oklahoma.ThispublicationisprintedandissuedbyOklahomaStateUniversityasauthorizedbytheVicePresident,Dean,andDirectoroftheDivisionofAgriculturalSciencesandNaturalResourcesandhasbeenpreparedanddistributedatacostof20centspercopy.0607