How do wasps parasitoids use monarchs as hosts?

Less is known about the extent to which other parasitoids attach monarchs, but at least one wasp in the family Braconidae has been reported in monarchs (Arnaud 1978). The closely-related queen, Danaus gilippus is parasitized by two Chalcid wasps as well as L. archippivora (Arnaud 1978). Current research in the Monarch Lab demonstrates that the wasp Pteromalus puparum (in the family Pteromalidae and the same superfamily, Chalcidoidea, as the two Chalcid wasps found in queens) could be an important pupal parasitoid (Oberhauser et al. in preparation). Pteromalus puparum wasps are tiny, and over 200 can emerge from one monarch pupa.