In the months of June and July the Red Pine (Pinus resinosa) and the white Pine (Pinus strobus) show by the exuding pitch that they are suffering from the attacks of an insect. The wounds occur on the main stem below, the insertion of the branch. On cutting into the bark the injury is found to be caused by a small larva, which, when full grown, measures 16 to 18 millimetres. The head is shining chestnut brown with black mandibles. The body is livid or blackish green, naked, with series of black dots, each dot giving rise to a single, rather stout, bristle.