This order contains the sawflies, bees, ants and wasps and is the third largest order of the class Insecta. There are about 16,300 species reported in North America.

Sawflies have the abdomen broadly joined to the thorax. Other Hymenoptera such as the bees, ants and wasps have the basal segment of the abdomen fused with the thorax and the abdomen separated from the thorax by a distinct constriction.