Therefore, it is general practice, when discussing the body of an apocritan in a technical sense, to refer to the mesosoma and metasoma (or gaster) rather than the "thorax" and "abdomen", respectively.

The evolution of a constricted waist was an important adaption for the parasitoid lifestyle of the ancestral apocritan, allowing more maneuverability of the female's ovipositor.

Larvae are legless and blind, and either feed inside a host (plant or animal) or in a nest cell provisioned by their mothers.

[6] Aculeata is a monophyletic group that includes those species in which the female's ovipositor is modified into a stinger to inject venom.

The social Aculeata feed their young prey (paper wasps and hornets), or pollen and nectar (bees), or perhaps seeds, fungi, or nonviable eggs (ants).

Some traditional taxa such as the Parasitica (containing many families of parasitoid wasps) have been found on molecular analysis to be paraphyletic.