Heterospecific Hymenoptera found inside the nests of bombus impatiens (Hymenoptera: Apidae).
The nests of social Hymenoptera are particularly attractive to species engaging in resource robbing due to their concentration of resources. Here, the identity of heterospecific intruders in Bombus impatiens Cresson (Hymenoptera: Apidae) nests are described, with a particular focus on intrusion by invasive species - Vespula germanica (Fab.) (Hymenoptera: Vespidae) and Anthidium oblongatum (Illiger) (Hymenoptera: Megachilidae). While V. germanica is well known as a resource robber, this is the first time Anthidium spp. have been documented entering the nest of a social heterospecific. Of 16 B. impatiens colonies placed in a field in Lansing, MI, eight had heterospecific intruders, including Apis mellifera L. (Hymenoptera: Apidae), A. oblongatum, and V. germanica. Motivations behind entering a foreign nest are discussed.