Observations on the nesting behaviour of seven species of Crabro (Hymenoptera,Sphecidae)

Summary

Data are presented on the nests and prey of seven species of Crabro from diverse localities in North America. In two instances (virgatus and largior) this is the first published report. Further information is provided for the following previously studied species: argusinus, advena, cribrellifer, latipes, and monticola. Behavioural differences among these species are not conspicuous. Most are rather general fly predators, but cribrellifer appears to show a strong preference for Asilidae. There are also differences in type of soil used for nesting and in antipredator behaviour such as approach flights and daily cycles of activity. Two species, largior and monticola, provision their nests early in the morning, before miltogrammine flies are active in numbers. All species probably make cells of two sizes, larger cells containing more prey and producing females, smaller cells males.