Patch-Specific Foraging by the Robber Fly Megaphorus willistoni (Diptera: Asilidae)

Abstract

The insect prey of the robber fly Megaphorus willistoni (Cole) were sampled in three habitat patches characterized by different plant species and assemblages of potential prey. The prey taken by M. willistoni varied with differences among sites in the relative abundance of Hymenoptera. Predator electivity was consistently positive for large bees, tiphiid wasps, and sphecid wasps and was usually negative or zero for small halictid bees and non-Hymenoptera. The relationship of the results to studies of the foraging behavior of individual robber flies is discussed