How one parasitic wasp becomes the victim—of another parasitic wasp

Karma is a real pest for parasitoids, tiny parasitic wasps that lay their eggs on caterpillars. That’s because the way they protect their hungry young from the caterpillar’s immune system sends out a chemical calling card that lures other parasites, which feast on the offspring, according to a new study.

For the parasitoid’s brood, a caterpillar is a walking nursery and buffet. But that brood is on the menu for wasps called hyperparasitoids, which lay their eggs on the parasitoid offspring. Researchers previously found that hyperparasitoids sniff out their victims using the distinctive aroma a plant emits when being munched by a parasitized caterpillar.