Mating occurs during periodic mating swarms when the winged males and queens emerge from the colony. Mating flights occur during many periods from early spring through summer. Most follow within a few days of a heavy rainstorm. After mating, the queen seeks a nest site and attempts to begin the colony. Colony development is slow.
Nests are inconspicuous for several months until a large population of worker ants is produced.
Ant nests usually are produced underground and colonies contain tens of thousands of workers. The large carpenter ants construct nests in wood that is almost always partially decayed. Other than the occasional carpenter ant colony, few ants in Colorado form a nest indoors, with the exception of the pharaoh ant. Worker ants forage constantly during the warmer months of the season. The workers lay down a chemical trail as they forage, which helps direct other workers to foods.