What are the Major Groups of Insects?
Insects are the most diverse group of animals in existence. With over a million described species, and estimates of total species count ranging up to 30 million, insects make up between half and 90% of all animalian biodiversity. This is all the more impressive because insects aren’t even an animal phylum, they’re just a class within phylum Arthropoda. The oldest known insect fossil is Rhyniognatha hirsti from the Devonian, about 396 million years old. Since then, insects have been diversifying, particularly since the emergence of flowering plants about 125 million years ago. The most primitive insect group is order Archaeognatha (jumping bristletails), which only has about 300 species. Along with order Thysanura (silverfish), these two orders are the only two within class Insecta that are wingless. Other wingless animals formerly classified as insects, such as springtails, proturans, and diplurans are now considered basal lineages apart from Insecta, and are instead placed in their ow
