A wasp is any insect of the order Hymenoptera and suborder Apocrita that is neither a bee nor an ant. This means wasps are paraphyletic with respect to bees and ants and all three groups are descended from a common ancestor. Although the most commonly known wasps are eusocial insects, living together in a nest with a queen and workers, the majority of wasp species are solitary insects, with each adult female living and breeding independently.
Wasps first appeared in the fossil record in the Jurassic. They are a very successful group of insects and have spread to all parts of the world except for the polar regions. They are also a diverse group with tens of thousands of described species. The largest social wasp is the Asian giant hornet, at up to 5 centimetres (2.0 in) in length; among the largest solitary wasps is the giant scoliid of Indonesia, Megascolia procer. The smallest wasps are solitary chalcid wasps in the family Trichogrammatidae, some of which are just 0.2 millimetres (0.008 in) in length.
Almost every pest insect species has at least one wasp species that preys upon it or parasitizes it, making wasps critically important in natural pest control. Parasitoidal wasps are increasingly used in agricultural pest control as they prey mostly on pest insects without damaging crops.
Social wasps are considered pests when they become excessively common, or nest close to buildings. People are most often stung in late summer, when wasp colonies stop breeding new workers; the existing workers search for sugary foods and are more likely to come into contact with humans; if people then respond aggressively, the wasps sting.
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