 Two particular species of social wasp it has been known to infect are "Polistes gallicus" and "Polistes dominula".Younger members of a wasp colony tend to be targeted, although "X. vesparum" displays parasitic behavior in all stages of this host.According to Fabio Manfredini of Pennsylvania State University, co-author of an animal behaviour study of this insect's odd life cycle, published on 8 October 2011, the parasite infects a European paper wasp and completely alters its worker caste behaviour.