Spring is the main swarming season for many subterranean termites. There are several subterranean termite species, and they don’t all swarm at the same time. (On the other hand, dampwood and drywood termites typically swarm in the summer.) Species generally swarm based on favorable weather conditions.
Varying conditions may mean that swarms will occur at different times. For example, some species prefer more moisture than others. Separation in swarm timing may be a matter of a few weeks, or time of day. Swarming also is linked to age and maturity of the colony. While there isn’t a distinct age, most native subterranean termite colonies will not produce a swarm unless the colony is at least three to four years old.