Comparative Nesting Behaviors of Crabro rufibasis and Crabro arcadiensis (Hymenoptera: Sphecidae: Crabroninae)

Abstract

The nesting behaviors of Crabro rufibasis (Banks) and C. arcadiensis Miller, 2 ground-nesting predatory wasps native to Florida, were compared in detail. Among the features examined were nesting habitat, male behavior, nest structure, nest construction, sequence of activities in the nest, daily activity patterns, orientation flights, hunting behavior, prey transport, provisioning and storing times, nest provisions, prey positions, egg placement, larval development, cocoon structure cleptoparasites, seasonal occurrence, and apparent population sizes. Emergence cages placed over completed nests of C. rufibasis of the January-February generation yielded wasp progeny and an unexpectedly large number of cleptoparasitic sarcophagid flies. Direct and circumstantial evidence suggested that C. rufibasis is primarily a winter species in southern Florida and has only a partial second generation in the spring, whereas C. arcadiensis is apparently univoltine in the spring. C. rufibasis and C. arcadiensis were remarkably similar behaviorally but differed partly in seasonal occurrence, choice of nesting sites, and proportions of fly families taken as prey. These apparent behavioral differences may have developed only recently as C. rufibasis moved into areas modified by man for fruit production and ranching. Both Floridian species differ from other known Crabro in having unusually long vertical burrows with nearly all cells within 11 cm of a vertical line through the entrance.