Nest usurpation and intercolonial cannibalism in Mischocyttarus mexicanus (Hymenoptera: Vespidae)

Previous data show that conspecifics are a threat to paper wasp foundresses (Polistinae) by usurping nests and stealing brood to feed to their own young. Such threats may strongly select for pleometrosis (group nest-founding) in wasps. In this paper, observations of nest usurpation and intercolonial cannibalism in the paper wasp Mischocyttarus mexicanus (Polistinae) are provided. Lone females were more commonly usurped and visited by foreign conspecifics. The only occurrence of intercolonial cannibalism also happened to a lone female. These observations are important for two reasons: (1) this is the first report of conspecific attacks in this species, and (2) they support previous reports that lone females are more vulnerable to attack than females in groups.