Thirty-five colonies of three species of carpenter ant were examined: 25 of Camponotus herculeanus, 9 of C. noveboracensis, and 1 of C. pennsylvanicus. Workings were examined in about 150 trees. No major differences were noticed in the biology of the first two species.

All individuals were taken from two overwintering, torpid, C. herculeanus colonies; the larger contained 6,000 workers, 550 winged forms, and 6,500 larvae. Larvae were of two sizes and it is thought that the life cycle covers two years in New Brunswick. Frequency curves of worker head widths show that there are majors and minors, the minors being more numerous, especially in small colonies.

Each colony typically occupied several trees, only one of which contained the brood; the others had less extensive workings. Entrances were underground and led to tunnels connecting the trees within each colony. Surplus wood chips were buried in the ground. Ant activity in the tunnels was continuous through the day and night; few ants were seen on the forest floor.

Woodpeckers are important enemies and had attacked one third of the brood trees.

The workings frequently assist wind breakage and damage butt logs. From the roots they extend to a height of 4-6 ft., occasionally higher. 1% of the spruce, and 2-4% of the balsam fir examined had been attacked. This may lead to loss of 10% of merchantable volume, and possibly a higher figure for eastern white cedar.