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.