Chrysalis-parasite
Guides
Pteromalus cassotis
Pteromalus cassotis is a gregarious parasitoid wasp in the family Pteromalidae that specializes in attacking monarch butterfly chrysalides. A single female may lay numerous eggs in one host, with documented emergences of up to 425 adult wasps from a single chrysalis. The species exhibits extreme female-biased sex ratios, averaging 90% female offspring.