In studying populations of wood-boring beetles in dead trees or logs, it is usually the larval form with which the worker must deal. The various species have different habits and although they may be present in very large numbers, some may do no direct damage to the wood. For any estimate of the existing damage-potential, larval identification is therefore an obvious prerequisite. During recent studies of wood-boring beetles in fire-killed pine in northern Ontario, the larva of Acmaeops proteus was by far the most common encountered, but its identity remained uncertain until a programme of rearing larvae from known adults was carried out. The apparent absence of a published larval description of this, one of the most common cerambycids in our eastern coniferous forests, has prompted the preparation of this brief description.