Life Cycle

Life for the Ichneumonid begins as an egg when females locate a host and oviposit her eggs in, on, or near it. The following photo provided by PBS Nature is that of Megarhyssa macrurus as she oviposits her egg onto the larva of a wood-boring horntail wasp.

When the larvae hatch, they either feed on the host from the outside (ecto-parasite), or from within (endo-parasite). When the host is dead or moribund, the larvae pupate (this is when endo-parasites emerge from the host). It is known that some hosts, although moribund, spend their last bit of energy to protect the parasitoids.

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This video by Natural Geographic takes us on a journey of the larval ichneumonidae life cycle. Note how the caterpillar, although wounded, protects the parasitoids while they pupate.