Symbioses Between Insects and Spiders: An Association BetweenLepidopteran Larvae and the Social Spider Anelosimus Eximius(Araneae: Theridiidae)

There are many instances of relationships between insects and spiders that are not simply relationships between predators and prey. Bristowe (1941) cites numerous examples either from his own extensive experience or from a broad review of the diverse literature. Moths have been reported to associate with spiders' webs both as adults and larvae. Thus Pocock (1903) reported a case of commensalism between the gregarious spider Stegodyphus sp. (Erisidae) and the moth Batrachedra stegodyphobius Walsingham. The unnamed species of Stegodyphus from South Africa had small lepidopteran larvae crawling about within the communal web. These fed upon "the carcases of the flies or other insects which, with infinite labour and patience, the spiders hauled up as near their nest as possible. . . ." Pocock states that pupation occurred within the nest (= web) and that, after emergence, adult moths moved about the web walking, leaping and fluttering. Reportedly the moths did not get caught in the sticky (cribellate) silk "being gifted apparently, like the spiders themselves, with some safeguard against the stickiness of the threads, which proved so fatal to other insects" (1903: 169). Brach (1977) reports that the webs of Anelosimus studiosus, in Florida are shared by a host of other arthropods including pyralid "webworms." He comments that the relationship between these other arthropods and the Anelosimus is not clear, but that the majority "are found in the periphery of senescent webs and may be physically isolated from contact with colony members by their own silken retreats" (1977:155). (1976:12-16) report on a pyralid moth