What is "larch sawfly"

The larch sawfly (Pristiphora erichsonii) is a species of sawfly. The adult sawfly resembles a black wasp, is about ½ inch in length with a thick waist and has brown to orangish markings on the abdomen. Larvae have black heads, gray-green bodies with white undersides, and are about 15–18 mm long when full grown. Larvae occur in groups and characteristically curl their bodies upward in a "J" shape when disturbed.

In the spring when larch trees are leafed out and the new growth is expanding, the female sawfly can be seen depositing eggs in new shoots near the branch tips.