SELECTION OF TERRESTRIAL GASTROPOD PREY BY CYCHRINE AND PTEROSTICHINE GROUND BEETLES (COLEOPTERA, CARABIDAE)

I examined the relative feeding preferences of five carabid beetle species for terrestrial gastropod prey. Scaphinotus marginatus Fischer, thought to be a snail specialist, discriminated among seven species of potential prey by size and species, with the slug Deroceras reticulatum (Muller) being the most preferred. Scaphinotus marginatus appears to use its elongated and narrowed mouthparts, head, and thorax to prey upon terrestrial snails without having to crush their shells. The relative feeding preferences of four pterostichine generalist predators (Pterostichus adstrictus Eschscholtz, P. pennsylvanicus LeConte, P. protractus LeConte, and P. surgens LeConte) for two species of small snails [Discus cronkhitei (Newcomb) and Euconulus fulvus (Muller)] also were examined. Although all four carabids ate E. fulvus in varying proportions, only P. protractus consumed D. cronkhitei. I suggest that snail shell thickness and differing feeding preferences affect which snail species are eaten by these pterostichines.