Wasp
Wasps first appeared in the fossil record in the Jurassic, and diversified into many surviving superfamilies by the Cretaceous. They are a successful and diverse group of insects with tens of thousands of described species; wasps have spread to all parts of the world except for the polar regions. The largest social wasp is the Asian giant hornet, at up to in length; among the largest solitary wasps is a group of species known as tarantula hawks, along with the giant scoliid of Indonesia ("Megascolia procer"). The smallest wasps are solitary chalcid wasps in the family Mymaridae, including the world's smallest known insect, with a body length of only , and the smallest known flying insect, only long.
Wasp
There are estimated to be 100,000 species of ichneumonoid wasps in the families Braconidae and Ichneumonidae. These are almost exclusively parasitoids, mostly utilising other insects as hosts. Another family, the Pompilidae, is a specialist parasitoid of spiders. Some wasps are even parasitoids of parasitoids; the eggs of "Euceros" are laid beside lepidopteran larvae and the wasp larvae feed temporarily on their haemolymph, but if a parasitoid emerges from the host, the hyperparasites continue their life cycle inside the parasitoid. Parasitoids maintain their extreme diversity through narrow specialism. In Peru, 18 wasp species were found living on 14 fly species in only two species of "Gurania" climbing squash.