When do subterranean termites usually swarm?

Subterranean termites typically swarm in the spring, and this swarming behavior is closely tied to environmental conditions, such as temperature and humidity. Specifically, swarming often occurs when temperatures rise and the humidity levels increase, which happens primarily between late winter and early summer. The months of January to June represent the ideal timeframe when conditions begin to warm up, allowing for the reproductive cycle of subterranean termites to manifest in the form of swarming. During this period, colonies produce winged reproductive termites, commonly known as alates, which leave the nest to mate and start new colonies.

While swarming might be observed outside of this general range under very specific conditions, the primary and most prevalent swarming period for subterranean termites is indeed from January to June, making this option the most accurate.