The insects are classified into about 32 orders and 939 families. Dragonflies and damselflies form the order Odonata (25 families). The word Odonata comes from the Greek for tooth and is a name derived using a classification devised by Fabricius. Johan Christian Fabricius (1745-1808) was a Danish entomologist and economist who classified insects based on their mouthparts, which he thought were more important than other traits like wings, because feeding provides the sustenance of life.
Entomologists have been puzzled as to why Fabricius chose the name Odonata for the dragonflies and damselflies since the mandibles of most insects are toothed and a name indicating "toothed mandibles" is no more significant for dragonflies than it would be for beetles or grasshoppers. For more information on the name Odonata see the article The significance of the dragonfly name "Odonata" by Clarence E Mickel in the Annals of the Entomological Society of America.
Front view of the head of a four-spotted chaser (Libellula quadrimaculata) showing the chewing mouthparts:
Side view of the head of a male southern hawker (Aeshna cyanea):
4 years ago