Spiders Inhabiting the Colonial-webs of the Fall Webworm, Hyphantria cunea DRURY (Lepidoptera : Arctiidae)

Abstract

Two hundred fifty-five spiders, representing 34 species and 10 families, were recorded from the colonial-webs of the fall webworm at two localities in Tokyo. The most common spider species was Misumenops tricuspidatus which accounted for 25.5% of the total number of spiders. The spider fauna in the colonial-webs varied somewhat between two localities and between generations. Mean number of spiders per colonial-web was 0.37. Frequency distribution of spiders inhabiting the colonial-webs was approximately fitted with Poisson distribution. Mean number of the fall webworm larvae per colonial-web was larger in the colonies of the 2nd instar larvae having no spider compared to those having spiders, but no differences were detected between the colonial-webs with spiders and without spiders in other instars. The rate of predation on 3rd and 4th instar larvae was the highest in female mature M. tricuspidatus in the laboratory condition.