The larvae of these pests feed for weeks on conifer foliage.
There are more than 100 species of sawflies known in the U.S., and the most common feed on conifer foliage. Coincidentally, the sawfly is not technically a fly. It is in the order
Hymenoptera, which includes ants, wasps, and bees. The common name “sawfly” comes
from the saw-like apparatus at the tip of the adult sawfly’s abdomen. It
uses this “saw” to slit plant tissue which allows for easy insertion of
eggs. Sawfly larvae resemble that of moth and butterfly caterpillars,
but have six or more pairs of false legs (prolegs) on their abdomen.
Caterpillars have five or fewer pairs of prolegs.
Source: The Morton Arboretum Photos: Gerald J. Lenhard, Louisiana State University, Bugwood.org; Steven Katovich, USDA Forest Service, Bugwood.org; USDA Forest Service - Region 8 - Southern , USDA Forest Service, Bugwood.org