阅读理解ThebrownwidowspiderbecameestablishedinSouthernCaliforniainearly2000andhasbecomepartofthelocalspiderfamilyinurbanLosAngelesandSanDiego．Thebrownwidowspideris

　　阅读理解

　　ThebrownwidowspiderbecameestablishedinSouthernCaliforniainearly2000andhasbecomepartofthelocalspiderfamilyinurbanLosAngelesandSanDiego．ThebrownwidowspideriscontinuingitsexpansioninSouthernCaliforniaandcouldpossiblymovenorthwardintoCentralCalifornia．

　　ThebrownwidowissuspectedtohaveevolvedinAfricaalthoughitwasfirstdescribedfromSouthAmericawhichaddsconfusionastowhereitmighthaveoriginated．ItisatropicalandsubtropicalspiderhavingestablishedpopulationsinHawaiiFloridapartsofAustraliaSouthAfricaandJapan．InNorthAmericathebrownwidowwasrestrictedformanydecadestotheFloridapeninsula．Howeveraroundtheyear2000itstartedshowingupinotherGulfCoaststates．BrownwidowsarenowknownfromTexastoGeorgiaandSouthCarolina．

　　Thebrownwidowbuildsitswebinprotectedsitesaroundhomesandinwoodyvegetationwithbranches．Sometypicalsitesselectedbybrownwidowsforwebbuildingareemptycontainerssuchasbucketsandnurserypotsmailboxesentrywaycornersundereavesstorageclosetsandgaragesundercarriagesofmotorvehiclesthatarestationaryforlongperiodsandtheundersidesofoutdoorfurniture．Theychooseplacesthataremoreexposedthansiteschosenbyblackwidowsandthereforeappeartobeathigherriskforinteractionswithhumansasfarasbitesareconcerned．

　　Onerecentstudydemonstratesthatthebrownwidowspiderislesspoisonousthanotherwidowspecies．Thereasonfortheweakereffectofbrownwidowbitesonhumansispossiblybecausethebrownwidowdoesnothavemuchpoisonasitslargerrelativesbutitisreallyathreattohumansastoitspoison．Thetwomajorsymptomsofabrownwidowbitewerethatthebitehurtwhenitwasgivenanditleftaredmark．Thesetwosymptomsarenotmuchdifferentfromthebiteofnormalhouseholdspiders．

　　Thereisnospecificinformationregardingthecontrolofbrownwidowsbyfarmchemicals．Mostcurrentadviceiswhatisusedforcontrollingspidersingeneral．Thereforemostcommerciallya