Ryan S. Davis, Arthropod Diagnostician, and Ricardo A
Transcript of Ryan S. Davis, Arthropod Diagnostician, and Ricardo A
Published by Utah State University Extension and Utah Plant Pest Diagnostic Laboratory January 2013ENT-163-12PR
SpidersRyan S. Davis, Arthropod Diagnostician, and Ricardo A. Ramirez, Extension Entomologist
DO YOU KNOW
• Spidersarebeneficialpredatorsthatfeedonpestandnon-pestinsects.
• ThemajorspiderofmedicalconcerninUtahistheblackwidow.
• Brownreclusespidersdo not occurinUtah.• Thereisnostrongscientificevidencethat
hobospiderbitescausenecrotic(flesheating)lesions.
• Indoormanagementofspidersisbestdonebyvacuuming,cleaning,sealingcracksandcrevicesaroundthehome,andtolerance.
• Pesticidesareonlyrecommendedinoutbreaksituationsorwhenmedicallyimportantspiders(blackwidows)arepresent.
Fig.1.Bandedorb-weaverspider(Argiope trifasciata).
INTRODUCTIONSpidersarearachnids,agroupthatincludesother8-leggedarthropodsliketicks,mites,sunspiders,scorpions,andharvestmen(daddylonglegs).Thereareapproximately621speciesofspidersknowntooccurinUtah(AllredandKaston,1983).Spidersarebeneficialpredatorsandthemajorityofthemareharmlesstohumans.Muchfearofspidersresultsfromthefewspeciesthatcanbedangeroustohumans,suchastheblackwidowandbrownreclusespiders,andfromthemanyfalsefactsandmythsaboutspiders.Themajorityofspidershaveweakvenomandareonlycapableofharmingsmallpreythattheysubdueandconsume.Ifbittenbyoneofthesespiderstheremaybesomeslightirritationandswellingsimilartoamosquitobiteorbeesting.ThemajorspiderofmedicalconcerninUtahistheblackwidow.
Allspidersarepredatoryandusedifferentstrategiesforcapturingprey.Somespiderspeciesambush
BIOLOGY
oractivelyhunttheirprey,whileotherstraptheirpreyusingsilkwebs.Spiderscanproduceuptoeightdifferenttypesofsilkthatareusedfordifferentpurposesincludingmakingdraglines,webframethreads,eggsacs,andstickysilkusedtocaptureprey.Spidersinjectvenomintopreyviathefangs,andusefangsandgrindingmouthparts(chelicera)togrindpreyintoanunrecognizablemass.Theyregurgitatedigestiveenzymesintoorontothepreyandsucktheliquidbackthroughthemouth.Thisregurgitationandsuckingcanalsobedonethroughfangbiteholesasincrabspiders.Notethatspidersdonotsuckfoodthroughtheirfangs;fangsareconnectedtothevenomglands,notthestomach.
IDENTIFICATION
Spidersarenotinsectsandarerecognizedbyhavingfourpairsoflegsand2bodyregions(cephalothoraxandabdomen)(Figs.2-3).Theyhavebetween0and4pairsofeyesdependingonthespecies.Themostcommonnumberofeyesis6or8.Spiderspossessapairofpedipalpsormodifiedmouthparts,oftenmistakenforantennaewhichspidersdonothave,usedforsensing,mating,andfeeding.The“boxinggloves”attheendofpedipalpsorenlargedpalpsarepresentonallmalespiders.Forthemostpart,malesspidersaresmallerthanfemales.Newlyhatchedspidersarecalledspiderlingsandlooklikeadults,butsmaller.Theywillmoltmanytimes,continuingtogetlargerastheydeveloptoadulthood.
Spidersarethemostfrequentlysubmittedarachnid
pedipalps
fangs/chelicera
legs
cephalothorax
abdomen
spinnerets
abdomen
thorax
head
wings
legs
antennae
SPIDERS
INSECTS
Figs.4-5.(Top)Totalarachnidorders,and(bottom)mostfrequently
submittedspiderssubmittedtotheUtahPlantPestDiagnosticLabbetween
(UPPDL)1978and2010.
0 200 400 600 800 1000 1200 1400
Funnelweb Spiders
Widow Spiders
Wolf Spiders
Orb-Weaving Spiders
Ground Spiders
Sac Spiders
Woodlouse Spiders
Jumping Spiders
Cellar Spiders
Huntsman Spiders
Crab Spiders
Crevice-Weaving Spiders
Hacklemesh Spiders
Total Spiders Submitted
UTAH’S SPIDERS
totheUtahPlantPestDiagnosticLab(UPPDL),however,otherscommonlyencounteredincludemites(mostlyplant-feedingspidermites)windscorpions/camelspiders,ticks,pseudoscorpions,truescorpions,andharvestmen(Fig.4.).Thereareover600spiderspeciesinUtah,howeverpeoplenormallyencounteronlyafewofthese.Identifyingspiderstospeciesisdifficult,butspiderfamilies,orgroupsofspidersthatlooksimilarandhavesimilarhabits,canberecognizedwithsomepractice.InUtah,thereare13spiderfamiliesthatareregularlyencounteredinandaroundhomes.Seethegraphbelow(Fig.5)foralistofthecommonspiderssubmittedtotheUPPDLandtheirfrequency.Themostfrequentlyencounteredgroupisthefunnel-webspiders,whichincludesthehobospider.HobosarethemostcommonysubmittedspiderbecauseoftheirhabitofmigratingindoorsfromAugusttoOctobertofindmates.
Figs.2-3.(Top)Basicspideranatomy.(Bottom)Basicinsectanatomy.
Funnel-Web Spiders: AgelenidaeThemostcommonfunnelwebspidersincludethehobo(Fig.6)andgrassspiders(Fig.7).HobospidersareverycommoninhomesbetweenAugustandOctoberinUtah.Moreinformationonthehobospidercanbefoundonthehobospiderwebsite.Grassspidersareverycommonoutdoorsinsmallshrubs,grass,andinrockwallsandwoodpiles.Websareflatsheetswithafunnelandasmallholeinthemiddle.Grassspidersarenotofmedicalconcern.
Comb-Footed Spiders: TheridiidaeThisfamilyisnamedaftercomb-likeleghairsthatallowthespiderstowalkontheirdisorganizedcobwebs.Theytypicallyhangupsidedown,andmoverelativelyslowwhenwalkingoutsideoftheirwebs.Worldwide,comb-footedspidersinthegenusLatrodectus(widowspiders:Fig.8)aresomeofthemostvenomousspiders.Othercombfootedspiders(Figs.9-10)canresemblewidowspiders,butdonothavethesameharmfulvenom.
Wolf Spiders: LycosidaeWolfspidersareground-huntingspiders.Theyareeasilyrecognizedbytheireyepattern(Fig.11).Aftermating,femalewolfspidersattachtheeggsactothespinneretsuntilegghatch(Fig.13).Uponegghatch,tinyspiderlingscoverthemother’sbackforprotectionandremainthereabout1week(Fig.12).Wolfspidersareverycommoningardensandturfandshouldbeconsideredbeneficial.
Orb-Weaving Spiders: AraneidaeOrbweaversbuildtheclassiccircular/spiralweb.InUtah,thecat-facespider(Figs.14-15)andbandedgardenspider(Fig.1)arethemostcommon.Thecatfacespiderisusuallyfoundmakingwebsnearlightswhereitcapturesinsects.Thebandedgardenspider(Fig.1)mayencounterhumanactivityinthefallwhenthefemalesearchesforaplacetolayitseggsac.Thesespiderscanhelpreducethenumberofflyinginsectsaroundthehomeandshouldbeleftalone.
Ground Spiders: GnaphosidaeGroundspiders(Figs.16-17)aremostlynocturnal,ground-dwelling,wanderinghuntersfoundinleaflitter,beneathrocks,andwithinandunderdecomposingwood.Silkisusedprimarilyformakingsheltersandforenclosingeggsacs--nothunting.Thesespiderscanoccasionallybefoundindoorsontheground,orclimbingonwallsorceilings.
Sac Spiders: ClubionidaeTheyellowsacspider(Figs.18-19)isacommonhouseholdspiderthatcanbeseenwalkingonwallsandceilings.Duringtheday,itmakesawhitesilkenretreatwheretheceilingandwallsmeet,orincorners.Thevenomisnotharmfultohumans;however,bitescanbepainfulandleavearedbump.Theyaremoreaggressivethanmostspidersandcanbitemultipletimesifmishandledorifcaughtinclothesorbedding.Similarsacspiderscanbefoundoutsideinrolledplantleaves.
Fig.6
Fig.8
Fig.7
Fig.9
Fig.10
Fig.12
Fig.15Fig.14
Fig.16 Fig.17
Fig.18 Fig.19
Fig.11
Fig.13
Page4
Jumping Spiders: SalticidaeJumpingspiders(Figs.22-23)areverycommonbothinsideandoutsidethehouse.Thesesmall,“furry”spidershavegoodvision(Fig.22)andhuntpreyinacatlikefashion.Theyareactiveduringthedaytimeandcanfrequentlybeseenaroundwindowsandbrightareaswherethelighthelpsthemlocateprey.Duringrainyorcloudydays,theycanbefoundhidinginasmallwebretreat.Retreatsarealsousedforprotectionduringmolting,egglaying,andhibernation.
Cellar Spiders: PholcidaeCellarspiders(Figs.24-25)generallyhavelong,slenderlegsandonly6eyes(Fig.24).Theyareoftenfoundindoorsindark,secludedplaceswheretheycanfillunusedareaswiththeclassic“creepy”cobwebs.CertainspeciesofPholcidaecanbeeasilymistakenforbrownreclusespiders(Loxosceles);however,theyarenotharmfultopeople.
Huntsman Spiders: SparassidaeOccasionally,large,goldenspiderswithblack“socks”onthelegs(Fig.26)aresubmittedtotheUPPDLinthefallforidentification.ThegoldenHuntsmanspideristhemostcommonHuntsman,orgiantcrabspider,inUtah,andcangrowupto2-3inchesacross!Theirflatshapeallowsthemtohideeasilyincracks,behindcurtains,andinthecrevicesoftreebark(Fig.27).
Crab Spiders: ThomisidaeCrabspidersgettheirnamefromtheirabilitytowalksideways.Asambushhunters,theywaitmotionlessforpreytocomeintorange.Manyarecoloredtomatchflowers(Fig.28),plants,androcks(Fig.29)whichhelpsthemcaptureprey.Afterenvenomatingprey,crabspiderssucktheprey’sliquefiedinsidesoutofthesmallbiteholes.Whenfeedingisfinished,thepreyappearsintact.
Crevice-weaving Spiders: FilistatidaeMostcommonlyoccrringinUtah’ssoutherncounties,thecrevice-weavingspider(Figs.30-31)canmakeitswebsaroundtheoutsidesofhomeswherecrevicesorgapsprovideprimehabitat.Thisisanotherspiderthatisoftenmistakenforthebrownreclusespider(Loxosceles reclusa),butisnotharmfultohumans.
Fig.20 Fig.21
Fig.22
Fig.25Fig.24
Fig.23
Fig.26 Fig.27
Fig.28 Fig.29
Fig.30 Fig.31
Woodlouse Spiders: DysderidaeWoodlousespiders(Figs.20-21)lookvisciousbecausetheirmountpartsandfangsprojectoutwardfromthebody.Theirpresenceandabundancecanbeassociatedwiththatof“potatobugs”(isopods:Fig.20),theirprimaryprey.Theyarecommonlyfoundoutdoorsingardensandlandscapes,butoccasionallycomeindoors.Woodlouse
OfUtah’sspiders,theblackwidowisthemajorspiderofconcernandshouldbecontrolled.Allotherspidersshouldbetoleratedoutdoors,andminimalmanagementpracticescanreducetheirpresenceindoors.Ideally,theyshouldbecapturedandreleasedwhenfoundinside.Ifadditionalcontroltechniquesaredesiredpleaseuseoneoracombinationofthetechniquesbelow.
Mechanical/Physical: Exclusion• Sealallcracksandcrevicesleadingintothe
homewithsiliconecaulk,expandablefoam,orscreen.
• Installweatherstrippingarounddoorsandwindows,especiallyalldoorsleadingtotheoutside,includingthegaragedoor.
CleaningandHabitatModification• Vacuumregularly.Spiders,webs,andegg
sacscanbesuckedup,directlyeliminatingtheproblem.
• Minimizeclutter.Spiderslovesecludedplacestohideandlayeggsacs.Simplifytheenvironmentinsidebycleaningregularlyandstoringclutterinsealablestoragebins.Outside,moveoreliminaterockandwoodpiles,oranythingthatcreatesspiderhabitat.
• Replaceexteriorlightingwithsodiumvaporlights(yellowbulbs)whicharelessattractivetoinsects.Insectsareattractedto“normal”exteriorlightsatnight.Theincreaseininsects(spiderfood)willalsoattractanincreasednumberofspiderslookingforfood.
MonitoringSpiderstickytrapsthataresoldinlawnandgardencenterscanbeplacedalongbaseboardstoprovideanindicationofwhattypeofspidersarepresent,wherehteyarecomingfrom,andcanprovidesomecontrol.TrapscontaininghobospiderattractantsarenotrecommendedforindoorusebetweenAugustandOctober,asthismayleadtoanincreaseinhobospidersinthehome.
Chemical: Insecticidesshouldonlybeusedforspidersifthereisaseriousinfestation.Avoidcalendar-basedspraysforspidersthatput“barriers”aroundstructures.Ifchemicalsarenecessaryforspiders,theyshouldbetargetedandtimedwithspideractivityandlifecycles,andatmakingdirectcontactwiththespider.Insecticidaldustscanprovidesome
CONTROL controlofspidersinvoidsandsecludedplaces,andcanevenbepuffeddirectlyontospiderwebs.Aerosolformulationscanbeeffectivewhendirectlysprayedataspider,buthaveminimalresidualeffectagainstspiders.Thereareover900insecticidesregisteredforcontrolofspidersinUtah.Themostcommonactiveingredientsare:deltamethrin,lambda-cyhalothrin,permethrin,pyrethrin,andtetramethrin.Whenusingsprays,microencapsulatedformulationsofinsecticidesaremosteffectiveagainstspidersoutdoors.Followingaretipsonchemicalcontrolofspiders.
• Insecludedareas,crawlspaces,cracksandcrevices,orwallvoids(areaswherepeoplewon’tbecomingincontactwithchemicals),useadustformulationofaninsecticidelikeTriDiepurchasedatthelocalhomeandgardenstore.Donotusethisproductasabroadcasttreatment,wherepeoplemaycomeincontactwithit.
• Liquidordustinsecticidesmaybeapplieddirectlytowebs(thisworksespeciallywellforblackwidowspiders).
• Aerosolsprayscanbeusedtodirectlysprayspiders;spidersnotdirectlycontactedwiththistreatmentwillnotdie.
• Ifanoutsidetreatmentisdesired,insecticidespraysarebesttimedwhenhoboeggsacsarehatching.Thiswilldependlargelyontemperature,butyoucanexpecteggstohatchfrommidMaytomidJuneinnorthernUtah.
Bite Prevention Tips• Tokeepwanderingspidersoutofyourbed,
removethebedskirtandpullthebedoutfromthewallabout8inchesfromAugusttoOctober.
• Takecautionwhenpickingclothesupoffthefloororinlaundrybaskets.Spidershidingintheseclothescanbemistakenlygrabbed,resultinginabite.
• Shakeoutclothingbeforeputtingiton,especiallyiftheclothingwasonthefloor.
• Storechildren’stoysoffofthefloorsospiderscan’tcanhideunderthem.
• Wearalongsleeveshirtwithsleevestuckedintogloveswhenworkingoutdoors,especiallyaroundrockorwoodpiles.
OTHER ARACHNIDS
UtahStateUniversityiscommittedtoprovidinganenvironmentfreefromharassmentandotherformsofillegaldiscriminationbasedonrace,color,religion,sex,nationalorigin,age(40andolder),dis-ability,andveteran’sstatus.USU’spolicyalsoprohibitsdiscriminationonthebasisofsexualorientationinemploymentandacademicrelatedpracticesanddecisions.UtahStateUniversityemployeesandstudentscannot,becauseofrace,color,religion,sex,nationalorigin,age,disability,orveteran’sstatus,refusetohire;discharge;promote;demote;terminate;discriminateincompensation;ordiscriminateregardingterms,privileges,orconditionsofemployment,againstanypersonotherwisequalified.Employeesandstudentsalsocannotdiscriminateintheclassroom,residencehalls,orinon/offcampus,USU-sponsoredeventsandactivities.ThispublicationisissuedinfurtheranceofCooperativeExtensionwork,actsofMay8andJune30,1914,incooperationwiththeU.S.Dept.ofAg.,NoelleE.Cockett,VicePresidentforExtensionandAgriculture,UtahStateUniversity.
Page6UPPDL,5305OldMainHill,LoganUT84322,utahpests.usu.edu T:435.797.2435
Precautionary Statement:UtahStateUniversityExtensionanditsemployeesarenotresponsiblefortheuse,misuse,ordamagecausedbyapplicationormisapplicationofproductsorinformationmentionedinthisdocument.Allpesticidesarelabeledwithingredients,instructions,andrisks,andnotallareregisteredforediblecrops.“Registereduse”pesticidesmayonlybeappliedbyalicensedapplicator.Thepesticideapplicatorislegallyresponsibleforproperuse.USUmakesnoendorsementoftheproductslistedherein.
IMAGES & REFERENCESFigures: 1,4-6,12-13,26RyanS.Davis,UtahStateUniversityExtension. Figures: 31 EdwardL.Manigault,ClemsonUniversityDonatedCollection,Bugwood.org.Figures: 2-3ErinHodgson,IowaStateUniversity. Figures: 33RichardL.Coviello,UCDavisIPMProgram.
Figures: 7,9,16-25,29 JosephBurger,Bugwood.org. Figures: 34 GaryAlpert,HarvardUniversity,Bugwood.org. Figures: 8,14-15,32WhitneyCranshaw,ColoradoStateUniversity,Bugwood.org. Figures: 35 UniversityofIdaho.Figures: 10 UniversityofWisconsin,DepartmentofEntomology,Bugwood.org. Figures: 36 DavidCappaert,MichiganStateUniversity,Bugwood.org.Figures: 11 JoelSmith,UtahStateUniversity. Figures: 27MarieKnight,UniversityofFlorida,Bugwood.org. Allred,D.M.,andKaston,B.J.1983.AlistofUtahspiders,withtheirlocalities.GreatBasinFigures: 28JonYuschock,,Bugwood.org. Naturalist,April.Vol.43,No.3:pp.494-522.Figures: 30,37SturgisMckeever,GeorgiaSouthernUniversity,Bugwood.org.
ADDITIONAL RESOURCES1.Utah’sTop20Arachnids 4.SpiderMyths:UniversityofWashingtonBurkeMuseum
2.ColoradoStateUniversityFactSheet 5.SpidersofNorthAmerica(Book)
3.UniversityofCaliforniaDavisFactSheet 6.TheBiologyofSpiders(Book)
Spider Bites • Ifyouseeaspiderbite,youshouldcatchthespiderforidentification.Findingarandomspiderinthehouse
afteramysteryskinirritationoccursdoesnotimplicatethespider.• Cleananddisinfectthebiteusingatopicalaniseptic,andcoverwithasterilebandage.• Monitorthebiteandvisityourdoctorifsymptomsprogress.• Secondarybacterialinfectionsarepossibleafteranyspiderorinsectbite,andcanbecomeseriousifleft
untreated.
Figs.32-37.OthercommonarachnidsinUtah.Thepicturesarenottoscale.Ingeneral,ticks,mites,andpseudoscorpionsaresmall,whileharvestmen,sunspiders,andscorpionsarelarger.(Toplefttoright)harvestman(daddylonglegs);camelspiderorsunspider;RockyMt.woodtickfemaleandmale.(Bottomlefttoright)pseudoscorpion;two-spottedspidermites;scorpion.
Fig.32 Fig.33 Fig.34
Fig.35Fig.37
Fig.36
FactSheetSeries:Insects—Beneficial;Structural;Nuisance;Biting,Stinging,HealthRelated