A. obliqua may complete development from egg to adult in less than 21 days. Various stages overwinter, depending on species, giving rise to adults in spring.
Adults feed on pollen, nectar and aphid honeydew.
Females must feed on pollen for proper egg maturation. Females oviposit in the midst of aphid colonies, using honeydew as an ovipositional stimulant, and laying hundreds of eggs each. There are three larval instars. Larvae pierce aphids with their mouth hooks, sucking fluids from the bodies before moving to other prey. Each larva may consume hundreds of aphids during its development.