[4] Upon encountering a suitable pupal host the Nasonia female uses her ovipositor (stinger) to drill a small hole through its chitinous outer puparium.

Though the Nasonia young develop inside of the host's puparium, as they do not directly enter the body of their prey they are considered ectoparasites.

Specifically, the venom causes developmental arrest in the host, thus redirecting energy from this process toward pathways that produce nutrients required by the developing Nasonia larvae.

The Nasonia males, which emerge several hours before the females, escape by chewing small holes in the hosts puparium.

The males wait by the escape holes for the emerging females (typically their sisters) upon which they immediately court in the attempt at mating.