The Tenthredinidae is the largest family of sawflies, with well over 6000 species worldwide. Larvae are typically herbivores and feed on the foliage of trees and shrubs, with occasional exceptions that are leaf miners, stem borers, or gall makers. The larvae of externally-feeding species resemble small caterpillars. Metamorphosis is complete.
The family has no easily-seen diagnostic features, though the combination of 5-9 antennal flagellomeres plus a clear separation of the first abdominal tergum from the metapleuron can reliably separate them. These sawflies are often black or brown, and from 3-20 mm long. Like other sawflies they lack the slender "waist," or petiole, between the thorax and abdomen, which are instead broadly joined.
Females use their sawlike ovipositor to cut slits through barks of twigs, into which translucent eggs are wedged, which damages the trees. They are common in meadows, and in forest glades near rapid streams. Adults eat little, while larvae feed on foliage of streamside trees and shrubs, especially willow.