Three specimens of the last instar larva of Herculia intermedialis Wlk. were collected in the debris of sawdust, spider silk, etc. accumulated under a loose piece of bark on the trunk of a standing pine (Pinus rigida Mill.). These hibernating larvae were taken at Buzzards Bay, Mass., on the nineteenth of April. When disturbed the larvae wriggled backwards and dropped to the ground on a thread of silk. Prior to pupation, which occurred April 21, the caterpillars ate a quantity of bark and rotten wood. Just what their true food is remains to be discovered.