252 Million B.C.T. - The Insects Were Exterminated

During the Great Dying (the Permian-Triassic Extinction Event) of 252 million years ago, the only mass extinction (mass extermination) of insects occurred.

At the end of the Permian, the biggest mass extinction in history took place, collectively called the Permian–Triassic extinction event.  In this extinction event, it is estimated that thirty percent (30%) of all insect species became extinct making the Permian-Triassic extinction event the only mass extinction of insects in Earth's history until today.

The Permian had great diversity in insect and other invertebrate species, including the largest insects ever to have existed. The end-Permian is the only known mass extinction of insects, with eight or nine insect orders becoming extinct and ten more greatly reduced in diversity. Palaeodictyopteroids (insects with piercing and sucking mouthparts) began to decline during the mid-Permian; these extinctions have been linked to a change in flora. The greatest decline occurred in the Late Permian and was probably not directly caused by weather-related floral transitions.

Most fossil insect groups found after the Permian–Triassic boundary differ significantly from those that lived prior to the Permian-Triassic extinction. With the exception of the Glosselytrodea, Miomoptera, and Protorthoptera, Paleozoic insect groups have not been discovered in deposits dating to after the Permian–Triassic boundary. The caloneurodeans, monurans, paleodictyopteroids, protelytropterans, and protodonates became extinct by the end of the Permian. In well-documented Late Triassic deposits, fossils overwhelmingly consist of modern fossil insect groups.