Fact Sheet No. 5.553 Insect Ser ies|Home and Garden

Quick Facts• Cockroachesareassociated

withfilthandunsanitaryconditions.

• Knowntocarrydiseaseorganisms,theyhavenotbeentiedtomajordiseaseoutbreaksintheUnitedStates.

• Eggcases,nymphsandadultscanbefoundinaninfestedarea.

• Eliminateunnecessarysourcesofwater,foodandhidingplaces.

• Usetraps,residualandnon-residualinsecticidesprays,andinsecticideduststocontroloreliminatecockroaches.

*Colorado State University Extension entomologist and professor, bioagricultural sciences and pest management. Artwork by Thomas J. Weissling. 6/2012

© Colorado State University Extension. 7/95. Revised 6/12.

www.ext.colostate.edu

Cockroachesareamongthemostundesirableinsectintrudersinthehome.Theyareassociatedwithfilthandunsanitaryconditions,althoughtheyoccasionallyinvadethebest-kepthomes.

Thoughknowntocarryvariousdiseaseorganisms,cockroacheshavenotbeenassociatedwithanymajordiseaseoutbreaksinthiscountry.Theinsectsalsoproduceasecretionthathasarepulsiveodorandcanaffecttheflavoroffood.Cockroachescancauseallergicreactionswhensensitivepeoplecomeintocontactwithcontaminatedfoodorhousedust.

BiologyThreecockroachlifeformscanbefound

inaninfestedarea.Theeggcaseisthesizeandshapeofabeanandcontains10to20cockroacheggs(Figure1).Thefemalemaycarrytheeggsarounduntiljustbeforetheyhatchor,insomespecies,shemayhidetheminsomeprotectedarea.Astheeggshatch,youngcockroaches,ornymphs,emerge.Similarinshapeandcolortotheadults,theyaresmallerandwingless.Theirhabitatsandfoodpreferencesarethesameasthoseof adults.

Cockroachesareactiveatnight,sodaytimeobservationisagoodsignofaheavyinfestation.Theypreferprotectedareas,suchascracksandcrevices,torestandhide.Althoughcockroachespreferstarchyfoodsandmeats,theywilleatanythingofplantoranimalorigin.

Common SpeciesTherearemorethan50speciesof

cockroachesintheUnitedStates.However,onlyfivearelikelytobefoundinColorado.

TheGerman cockroachisthemosttroublesomeofallcockroaches.Oneofthe

smallerspecies,1/2inchwhenfullgrown,itislightbrownwithapairofparallelbrownbarsbetweentheheadandthefrontofthewings(Figure2).Thisspeciesusuallyisassociatedwithbuildingswherefoodispreparedorstored.Itcommonlymigratesfrominfestedareasintonearbydwellingsormaybecarriedinonfoodcontainers.Favoritehomehabitatsarewarm,moistareas,suchaskitchensinksandappliances,bathroomsinks,and furnaces.

TheAmerican cockroachisthelargestpestspeciesfoundinColorado–upto2incheslong.Itismahogany-coloredwithayellowmarginaroundtheheadandaroundtheshieldbehindthehead(Figure3).Althoughoccasionallyfoundinhomes,theAmericancockroachmorecommonlyisfoundinwarm,moistareasofindustrialor

by F.B. Peairs*

Cockroaches

Figure 2: German cockroach. (Photo from the K. Gray Image Collection, Oregon State University.)

Figure 1: Brownbanded (top) and American (bottom) cockroach egg cases.

commercialbuildings.Furnaceorboilerrooms,sewersandheattunnelsarefavoredenvironments.

Thebrownbanded cockroachissimilarinsizeandcolortotheGermancockroach.Itcanbedistinguishedbythelackofbrownbarsontheshieldinfrontofthewingsandbythepresenceoftwolightbandsacrossthewingsandabdomen(Figure4).Itprefersawarmer,drierenvironmentthantheGermancockroachandoftenisfoundinceilings,lightfixtures,furnitureandappliances,especiallytelevisions.

Theoriental cockroachisintermediateinsizebetweentheGermanandtheAmericancockroachandmuchdarker.Theadultshavewingsthatdonotreachtheendoftheabdomen(Figure5).Manyconsideritthemostrepulsivecommoncockroach,primarilyduetoitsstrongodor.Thisspeciespreferscool,damp,darkareas.Forthisreason,itofteniscalleda“waterbug.”Commonhabitatsincludesewerdrains,dampcrawlspaces,basementsandcellars.Infestationsaremostcommoninthespringandfall.

Thewood cockroachpreferstheoutdoorsandusuallyisfoundinwoodpiles,indeadtreesandunderbark.Attractedtolights,itoccasionallyentershomesandcausesgreatalarmbecauseitissoeasilyconfusedwithpestcockroaches.Thewoodcockroachhasawhitebandthatrunsaroundtheheadandtheshieldbehindthehead.Usuallyitdoesnotsurviveormultiplyindoors.

Cockroach ManagementThethreekeystoeffectivecockroach

managementarepreventionandsanitation,detectionandchemicalcontrol.Satisfactorycockroachcontrolwillnotbeachievedunlesseachofthesestepsisfollowed.

Prevention and Sanitation

Ifcockroachesaremigratingintoabuildingorfromanotherpartofabuilding,installweatherstrippingandcaulkingwhereplumbingpassesfrominfestedareasintouninfestedareas.Eliminatehidingplaces.Forexample,caulkcracksand crevicesindark,moistareastodiscouragecockroaches.Inspectitemsbroughtintoabuilding,especiallyfoodcontainers,furniture,appliancesandclothing.Theadultsandyoungareeasytorecognize.Becausesomecockroachesgluetheireggcasestovarioussurfaces,takeparticularcaretolookfortheeggs.

Cockroachesneedfood,waterandshelter.Waterisparticularlyimportant,whichiswhyinfestationsaremostcommoninkitchensandbathrooms.Makeanyplumbingrepairsandmodificationsneededtoeliminateasmuchstandingwateras possible.

Donotallowfoodparticlestoaccumulateinareasaccessibletocockroaches.Commonfeedingareasincludeunwasheddishes,petdishes,uncoveredpetfoodcontainers,litterboxes,wastecontainers,andareasunderrefrigerators,stoves,sinksandfurniture.Repairfaultyplumbingandeliminateunnecessarysourcesofwater.Reduceshelterforcockroaches;donotstoreunnecessarynewspapers,boxes,ragsandsimilaritemsthatprovidehidingplaces.

Detection

Detectionisanimportantelementofcockroachcontrol.Cockroachestendtoconcentrateincertainareas.Controlsaremoreeffectiveiftheyaretargetedatthesespots.Cockroachtraps,small,open-endedboxes,containanattractantandstickysubstancethatretainstheinsectsoncetheyenter.Usethemtolocateinfestationsandtodeterminewhenpopulationsrequireadditionaltreatment.Trapscanbeeffectiveincatchingtheoccasionalinvader,buttheywillnoteliminateestablishedcolonies.Trapsaremosteffectivewhenplacedagainstwallsundersinks,incabinetsandinbasementcorners.Iftwonightspasswithoutacapture,movethetraptoanotherlikelyarea.

Insecticides are poisons. Treat them as such.

Boric acid powder is relatively safe for humans, but do not expose children and pets to it.

Baits are long lasting and are most effective when placed in small amounts in many locations. Figure 3: American cockroach. (Photo from

the K. Gray Image Collection, Oregon State University.)

Figure 4: Brown-banded cockroach. (Photo from the K. Gray Image Collection, Oregon State University.)

Figure 5: Oriental cockroach. (Photo from the K. Gray Image Collection, Oregon State University.)

Chemical Control

Cockroachinsecticidesincluderesidualsprays,nonresidualsprays,dustsandbaits.Useacombinationforeffectivechemicalcockroachcontrol.

Allcockroachinsecticidelabelscontainimportantinstructionsandprecautionstoensureeffectivenessandtoprotectthesafetyofhumansandpets.Read, understand and follow all label instructions whenapplyinganyresidualspray,nonresidualspray,dustorbait.

Colorado State University, U.S. Department of Agriculture and Colorado counties cooperating. CSU Extension programs are available to all without discrimination. No endorsement of products mentioned is intended nor is criticism implied of products not mentioned.

Residual insecticide sprays leaveatoxicdepositonsurfacesandwillkillcockroachesforacertaintimeperiod,usuallytwotofourweeks.Applytocracksandcreviceswherecockroacheshideandareaswheretheywalkinsearchoffood.Sprayuntilthesurfaceiswet,butavoidoverapplicationsthatpuddleorrunoff.

Insecticidesarepoisonsandshouldbetreatedassuch.Usedimproperly,theycandamagelinoleum,carpets,drapesandpaint.Variousinsecticides,underavarietyofcommercialnames,areavailableforresidualtreatmentsagainstcockroaches.Someproductsareavailabletohomeowners,whileothersarelimitedtolicensedpestcontroloperators.Residualinsecticidetreatmentsaregenerallyeffective,butcockroaches,especiallytheGerman,havedevelopedinsecticideresistanceinmanypartsofthecountry.

Nonresidual insecticide sprayseliminatecockroachesonlyoncontact.Theywillnoteliminateaninfestationbutarequitehelpfulwhenusedwithresidualtreatments.Severalshort-lastingaerosolinsecticidescontaintheactiveingredientspyrethrinsorresmethrin.Theyirritatecockroachesandcanflushthepestsoutoftheirhidingplacesandforcethemintoareastreatedwitharesidualinsecticide.Thisflushingactionalsoisusefultodeterminewhetherornotcockroachesarepresent.Flushingagents,however,candrivethemintopreviouslyuninfestedpartsofthebuilding.

Insecticide dustscanpenetratecockroachhidingareasthatotherinsecticideswillnotreach.Whenappliedtodrylocations,theyhavealongerusefullifethanresidualsprays.Somedustscontainconventionalinsecticides,whileotherscontainnoorganicchemicals.

Boricacidpowder(alsoavailableasaresidualspray),availableunderseveralcommercialnames,isrelativelysafeforhumans,butdonotexposechildrenandpetstoit.Itcancauseskinirritationsifimproperlyhandled,anditwillharmhouseplants.Applyboricacidonlytohidingplacesandrunways.Itisslowacting.Donotexpectcompletecontrolforatleastoneweekafterapplication.Boricacidisamongthebestcockroachinsecticides.Combinedwithitsrelativesafety,thismakesitagoodchoiceforhomeowners.

Otherdustsarebasedonsilicaaerogelordiatomaceousearth.Theseareappliedinthesamemannerasboricacid.Theymaynotbeaseffectiveasboricacidbecausetheyarerepellenttothecockroach.However,theycankeepthepestsoutofcertainareas,suchaswallvoidsandattics.Whileboricacidispoisonous,silicaaerogelanddiatomaceousearthactbyrubbingofftheprotectivewaxesthatcoverthecockroach’sbodyandcausedeathbydehydration.

Baitscanbeappliedtoareasthatcannotbesprayedordusted.Theyconsistofanattractant,suchaspeanutbutterorsyrup,andanonrepellentinsecticide,suchasboricacid.Baitsarelonglastingandaremosteffectivewhenplacedinsmallamountsinmanylocations.Mostbaitsareavailableinchild-andpetproofcontainers.Baitsaremuchmoreeffectiveiftheyaretheonlyfoodsourceavailable.Goodsanitationisespeciallyimportantforthistypeof control.

Professional Pest ControlIfthesituationissevereoritisunclear

whattodo,professionalpestcontrolservicesareavailable.Thesecompaniesemploytrainedpestcontroloperatorsand

haveaccesstoinsecticidesandequipmentthatarenotavailabletoprivateindividuals.Chooseacompanywiththesamecareyouusetoselectotherservicesforthehome.

Biological ControlBiologicalcontrolusesoneorganism

tocontrolanother.Whereinsecticidesareundesirableoritisnotnecessarytoeliminatecockroachescompletely,considerabiologicalcontrolprogram.Suchprogramshavenotbeenpopularinthepastbecausemanyfindthebiologicalcontrolagenttobeasdistastefulasthecockroaches.Additionally,insecticideusewouldhavetobeminimizedoreliminated,becausethebeneficialorganismoftenisevenmoresusceptibletoinsecticidesthancockroaches.

Manykindsoforganismsattackcockroaches:toads,bacteria,protozoa,beetles,mitesandwasps.Parasiticwaspshavehadthemostsuccess.Thesearetinyinsects,harmlesstohumans,thatlaytheireggsinthecockroachcase.Theeggshatchintoimmaturewaspsthatfeedonthecockroacheggs.Waspscanreducecockroachnumbersdramaticallyandkeepthematlowlevels,buttheycannotcompletelyeliminatetheproblem.Parasiticwaspshavebeenusedsuccessfullyinnonresidentialofficebuildingsandwarehouses,butnotinresidentialbuildingswherethereismuchlesstoleranceofcockroachesandotherinsects.

ReferencesCornwell,P.B.1968.The Cockroach.VolumeI.

Hutchinson,London,391pp.Cornwell,P.B.1976.The Cockroach.Volume

II.Hutchinson,London,557pp.Roth,L.M.,andE.R.Willis.1957.The

medical and veterinary importance of cockroaches.SmithsonianMiscellaneousCollection134(10):1-147.