Ryan S. Davis, Arthropod Diagnostician, and Ricardo A ... · PDF fileRyan S. Davis, Arthropod Diagnostician, and Ricardo A. Ramirez, ... The “boxing gloves” at the end of ... sac

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