Wasps are every skinny-waisted hymenopteran that is not a bee
In entomology a wasp is any narrow-waisted Apocrita that is neither bee nor ant—leaving sawflies aside as broad-waisted cousins. Familiar yellowjackets and hornets in Vespidae live eusocially with queens and workers. Fossils appear by the Jurassic; Cretaceous rocks already hold many surviving superfamilies.
Technically "wasp" is a leftover category: every narrow-waisted hymenopteran that is neither bee nor ant. Because bees and ants evolved from wasp ancestors and sit deep inside the group, wasps do not form a single natural clade. The broad-waisted sawflies, which look wasplike, belong to a separate suborder. Apocrita, the waisted lineage, turns up in Jurassic rocks, and fig wasps with modern anatomy appear in Brazil's Crato Formation about 65 million years before the first fig trees.
Only Vespidae contains social species, among them yellowjackets, hornets and paper wasps, living with an egg-laying queen and sterile workers. Hymenopteran sex is set by haplodiploidy, which makes sisters unusually close relatives and helps explain why societies arise. Social wasps chew weathered wood into pulp with saliva to build combs of hexagonal cells, often inside a protective envelope, and their black-and-yellow warning dress is copied by harmless insects. Most species, though, are solitary: a mated female hunts alone, digging burrows or shaping mud cells like the vase-shaped nests of potter wasps.
Parasitoids dominate the numbers. An estimated 100,000 ichneumonoid species lay eggs in or on other insects, and the larvae eventually kill their hosts; pompilids target spiders, and some species parasitise other parasitoids. In one Peruvian study, 18 wasp species lived on 14 fly species within just two kinds of climbing squash. Growers exploit this appetite, using wasps against pests such as whitefly on tomatoes, and nearly every one of around 1,000 tropical fig species has its own pollinating wasp.
Extremes are striking. The Asian giant hornet reaches 5 cm, tarantula hawks drag off spiders far heavier than themselves, and a female giant ichneumon measures 12.5 cm including its wood-boring ovipositor. At the small end, the mymarid Dicopomorpha echmepterygis, at 139 micrometres, is the tiniest insect known. Culture noticed them early: Aristophanes staged The Wasps in 422 BC, and H. G. Wells gave giant wasps three-inch stings in 1904.
Source: Wasp
