[1] Female Aphidius nigripes emit pheromones soon after emerging from their pupa to attract winged males.

There is a trend for A. nigripes to preferentially allocate unfertilized male eggs to the earlier, smaller instars of aphids.

When the wasp larvae are nearly ready to emerge, they alter the behavior of their hosts in different ways depending on the time of year.

This leads to faster development of the wasp pupa due to increased temperature and decreases their risk of hyperparasitism.

Larvae completing their development late in the year cause the aphids to crawl downwards and find concealed spots.