Diet of the Big Brown Bat, Eptesicus Fuscus, From Pennsylvania and Western Maryland

We used fecal analysis to describe the diet of Eptesicus fuscus in Pennsylvania and western Maryland. We examined spatial variation in diet composition among three populations and temporal variation within a maternity colony. Temporal patterns of prey use were compared with similar data collected previously from a maternity colony in Indiana. Overall, Coleoptera (58–82%), especially Scarabaeidae (14–31%), were the dominant prey items. Hemiptera, primarily Acrosternum hilare (5–19%), were also major prey, and Tettigoniidae (not previously reported) were prey of two populations (6%, 17%). Significant spatial and temporal variation existed in diet composition among populations and use of major prey types, respectively. Comparison of temporal data collected in this study and in Indiana indicated a nearly identical pattern in the use of Scarabaeidae. These insects are abundant in the spring, and the data suggest widespread specialization on Scarabaeidae in April and May. Several insects preyed on by E. fuscus in this study are serious agricultural pests.