Spiders

Did You Know?

• Spidershave8legs,2bodysegments,and2palpsinsteadofantennae

• BlackwidowspidersarethemajorspiderofmedicalconcerninUtah

• BrownreclusespidersareNOTfoundinUtah

• Spidersarebeneficialorganismsbecausetheypreyuponmanyotherpestinsects

• Thebestcontrolmethodsforspidersincludeexclusion,cleaning,reducingclutter,andtolerance

Above:Figure1.Hobospiderfemaleandeggsac.

Right:Figure2.Bandedgardenspider.

IPM Fact Sheet # 1 July 2013

Utah

PESTPRESS

Management Tools for a Healthy Learning EnvironmentSpooky Spiders

General Info:

Spidersarearachnids,closelyrelatedtoother8-leggedcrittersliketicks,mites,harvestmen,andscorpions.Spidersshouldbeconsideredbeneficial,astheyhelptokillotherpestsbothinandoutofbuildings.InUtah,thereareonlyafewspidersthatweshouldtreatwithcaution.

What do they look like?

Spidersvaryinsizefromthetarantuladowntothecongenialjumpingspider,andsmaller.Mostspidershave8eyes,butotherscanhavebetween0to6eyes!Spidersdon’thaveantennae.Theyhavemodifiedmouthpartscalledpedipalps.Inmalespidersthesepalpsareenlargedandlooklikeboxinggloves.The“boxinggloves”arenotanidentifyingfeatureofthehobospider,butofmalespidersingeneral.Spidersonlyhavetwomajorbodysegments,whereasinsectshavethree.

Life Cycle

TherearemanydifferentkindsofspidersinUtah,buttheyallgothroughthesamebasiclifecycle:egg,immaturesthatgrow(molt)throughmanystages,finallyreachingthereproductiveadultstage.Thisprocesscantakemonthstoyearsdependingonthespider.

Common Utah Spiders

Themostcommonspidersarethefunnelwebspiders,includingthehoboandgrassspiders.Othercommonspidersincludethewoodlouse,orbweavers,wolfspiders,jumpingspiders,groundspiders,thehacklemeshweavers,sac,andwidowspiders.

Any products, services or organizations that are mentioned, shown or indirectly implied in this publication do not imply endorsement by Utah State University. Utah State University is an

affirmative action/equal opportunity institution.2013

Managing Spiders with Integrated Pest Management

• Caulk,sealandscreenallentrypointsintothebuildingtoexcludespiders.

• Changeexteriorlightingfromthestandardlightstosodiumvaporbulbstoreducepreyinsectsattractedtothebuilding.

• Vacuumregularlytosuckupspiders,webbing,andotherinsectswhichcanserveasfoodforspiders.

• Minimizecluttertoreduceareassuitableforspiderstohide,reproduce,andlayeggs.

• Usestickytrapsalongbaseboardstomonitorandhelpcontrolgrounddwellingspiders.

• Interiororexteriorinsecticidalspraysaregenerallyineffectiveatreducingspiderpopulationsinthelong-term,butmayprovidesomeshort-termknockdownandrepellency.

• Insecticidaldustscanbeusedinlowtrafficareassuchasboilerrooms,crawlspaces,andvoidsforlongerresidualcontrolofspiders.

Themajorspiderofmedicalconcernistheadultfemaleblackwidow.Thissolidblackspiderhasabulbusabdomen(hindsection)andaredhourglassonitsunderside(notontop).Thisspiderisfairlyclumsyoutofitswebandbitesusuallyonlyoccurifahandisstuckintheweb,orifaspiderisinadvertentlygrabbedwhilecleaninginareaslikethegarageorshed.

Blackwidowscomeoutatnightandcapturepreyintheircobweb-likewebs.Searchforwidowsatnightwithaflashlightandcarefullycrushspiders,ortreatthespiderdirectlywithanaerosolinsecticide.

Sinceblackwidowsdon’tmoveeasilywhenoutsideoftheirwebs,theywaitforpreytocometothem.Often,exteriorlightingwillattractmanyinsectsthattheycatchintheirwebsandeat.Changingtheexteriorlightingtosodiumvaporbulbs(theyellowbulbs)reducesattractionofpreyinsectsandwillhelpkeepwidowsawayfromthegrounds.

Right:Figure4.Femaleblackwidowspiderwithredhourglassontheundersideoftheabdomen(WhitneyCranshaw,CSU,Bugwood)

For more info, check out:

Spiders: USU Extension http://extension.usu.edu/files/publications/factsheet/spidersn-2012pr.pdf

Top 20 Arachnids: USU Extension http://utahpests.usu.edu/uppdl/htm/top-20-arachnids

The Hobo Spider Page: USU Extension http://utahpests.usu.edu/uppdl/htm/hobo-spiders

Spiders in the Home: CSU Extension http://www.ext.colostate.edu/pubs/insect/05512.html

Colorado School IPM:http://colordoipmcenter.agsci.colostate.edu/

Left:Figure3.Wolfspiderwithnewlyhatchedspiderlingsonherback