Where carpenter ants spend the winter

While splitting firewood recently, I discovered a colony of black carpenter ants in the wood. A large ash tree had died and was blown down in a wind storm last spring. The tree trunk was about 20 inches across. Cutting the log into blocks for firewood did not reveal the ants, but splitting the blocks with a sledge ax did.

There are five species of carpenter ants in Missouri. The black carpenter is the largest.

The largest ants in my photo are winged females about an inch long. The smaller ones with wings are males. Others, which do not have wings, are either major workers or minor workers. The winged ones are the reproductive ones. They grow their wings in late summer and spend winter in the nest waiting for spring, when they swarm out and fly away to start new colonies. After mating, winged females will lose their wings when they establish new colonies. After mating, winged males will die.

The dark areas in the photo indicate where the workers have carved out the nest cavity deep inside the tree trunk. This area is called a gallery.