In the war between parasite and host, the parasitic wasp and the pea aphid are locked in a battle for survival. New research shows that this cunning parasite sniffs out differences between protected and unprotected aphids, and alters its egg-laying strategy, in order to overwhelm aphid defenses and ensure survival of wasp offspring. The wasp lays an egg inside the pea aphid, where the egg hatches and converts the aphid’s insides into a wasp nursery. The wasp larva uses the still-living aphid as a food source, eventually pupating inside the aphid and emerging as a fully-formed mature wasp. However the pea aphid is not defenseless. It is protected by a bacterial symbiont.