Feeding Activity of Carabid Beetles and Spiders on Gypsy Moth Larvae (Lepidoptera: Lymantriidae) at High-density Prey Populations²

Pitfall traps and tree bands were used to collect arthropods at two sites in southeastern New Hampshire during the 1982–83 outbreak of gypsy moth. Pitfall traps caught more individuals (74% of total) than tree bands. Carabid beetles (59%) and spiders (22%) were the dominant groups. Twenty-two genera and 48 species of carabid beetles and 31 genera and 43 species of spiders were collected. Spiders had more species and a larger proportion (38%) collected under tree bands than did carabid beetles (12%).

Guts of all individuals were tested for presence of gypsy moth proteins using ELISA. Fourteen genera and 26 species of carabid beetles tested positive with the highest percent (50%) recorded for Calosoma frigidum Kirby. Twenty-eight genera and 31 species of spiders tested positive with the highest percent (57%) recorded for Haplodrassus bicornis (Emerton). Positive test results were generally higher in tree band collections for species in either group. Positive tests may have been overestimated in the carabid beetles through carrion feeding, and in the spiders because of the extended period required to digest meals.