Braconidae stinging caterpillar
Click on image to view larger. Parasitic wasps
Adults of many species are very small (ranging from 1/100 to 3/4 inch long). They vary in shape and coloration but usually have long, filiform or elbowed antennae, clear or colored wings with characteristic venation and a narrow waist between the thorax and abdomen. Many females have a spine-like ovipositor at the tip of the abdomen.
Larval stages of parasitic wasps develop inside or outside of a single host during one or more of the host developmental stages. Those that kill their hosts are called parasitoids. Most insect groups including aphids, beetles, caterpillars, flies, sawflies, scale insects and true bugs are attacked by parasitic wasps.
Biology and details of development vary with species. Adult wasps emerge from pupae and females seek suitable host insects into or on which to oviposit eggs singly or in clusters. Usually, a larva hatches from an egg and develops through several instars before forming a pupa. However, some parasitic wasps, such as Copidosoma spp., undergo polyembryony, whereby an egg inserted into a host divides and gives rise to hundreds of larvae.