The various species of wasps fall into one of two main categories: solitary wasps and social wasps. Adult solitary wasps live and operate alone, and most do not construct nests (below); all adult solitary wasps are fertile. By contrast, social wasps exist in colonies numbering up to several thousand individuals and build nests—but in some cases not all of the colony can reproduce. In some species, just the wasp queen and male wasps can mate, whilst the majority of the colony is made up of sterile female workers.
The following characteristics are present in most wasps:
- Two pairs of wings (except wingless or brachypterous forms in all female Mutillidae, Bradynobaenidae, many male Agaonidae, many female Ichneumonidae, Braconidae, Tiphiidae, Scelionidae, Rhopalosomatidae, Eupelmidae, and various other families).
- An ovipositor, or stinger (which is only present in females because it derives from the ovipositor, a female sex organ).
- Few or no thickened hairs (in contrast to bees); except Mutillidae, Bradynobaenidae, Scoliidae.
- Nearly all wasps are terrestrial; only a few specialized parasitic groups are aquatic.
- Predators or parasitoids, mostly on other terrestrial insects; most species of Pompilidae (e.g. tarantula hawks), specialize in using spiders as prey, and various parasitic wasps use spiders or other arachnids as reproductive hosts.
- A pair of talons