Diamondback Moth Parasitoid Wasp

Diadegma semiclausum is native to Europe but has spread to, or been introduced to, other parts of the world, including Asia, Egypt, South Africa, Hawaii, Australia and New Zealand. Its preferred temperature range is between 15 and 25 °C (59 and 77 °F), so in tropical countries it is found in cooler climates at higher altitudes. It is attracted to cruciferous vegetables on which diamondback moth larvae are feeding, responding to chemical cues released by the larvae and the damaged tissues. It also parasitises the leek moth (Acrolepiopsis assectella).

The adult female Diadegma semiclausum searches out first instar larvae of its host and lays a single egg inside; it does not lay an egg if the larva has already been parasitised. The female wasp can lay several hundred eggs over the course of about three weeks if it finds sufficient nectar or other sugary food to sustain it. When the egg hatches, the wasp larva feeds inside the moth larva, and when the moth larva makes a cocoon, the wasp larva pupates inside. It emerges after eight to ten days, leaving a dry husk behind. The whole cycle takes about 19 days.