Termite Swarmer

Termite swarmers, or alates, are the winged reproductive caste produced by a mature termite colony once it has grown large enough to spare individuals for dispersal. Triggered by warm, humid conditions—classically a mild day following rain in spring or early summer—hundreds to thousands of swarmers erupt simultaneously from a single colony in a brief, synchronized flight.

The swarm itself lasts only minutes to an hour. Swarmers are weak fliers and are quickly scattered by wind, which is why homeowners often notice them clustered at windows, porch lights, or other bright surfaces rather than in open flight. Most swarmers are eaten by birds, spiders, ants, and other predators within a short time of taking flight, and only a small fraction survive to found new colonies.

Because swarmers are the visible sign of a termite colony's reproductive cycle, their appearance indoors or near a foundation is often used as a general indicator of termite activity in the surrounding area, though the swarmer itself does not cause structural damage.

• Body dark brown to black, soft, roughly 1/4–3/8 in (6–10 mm) long excluding wings
• Two pairs of long, milky to smoky-gray wings of equal length and shape, extending well past the tip of the abdomen
• Straight, bead-like (moniliform) antennae
• Thick waist with no constriction between thorax and abdomen
• Lookalike: winged ants, which have two pairs of unequal-length wings, elbowed antennae, and a narrow pinched waist
• Discarded, shed wings littering a windowsill are a classic sign a termite swarm has occurred nearby

Swarmers emerge from subterranean, drywood, or dampwood termite colonies located in soil, tree stumps, buried wood, or structural lumber. Timing varies by species and region: many subterranean species swarm on warm, still, humid afternoons in spring, while some drywood species swarm in late summer or fall, often at dusk and attracted to light. Termites and their swarms occur worldwide in temperate and tropical regions wherever suitable wood or cellulose material and moisture are present.

After a brief flight, swarmers land, break off their wings along a pre-formed suture, and pair up with a partner in a behavior called tandem running. A successful pair digs into soil or wood together to excavate a small chamber, mate, and found a new colony as king and queen. Within the parent colony, the vast majority of termites are sterile worker and soldier castes that feed on wood, leaf litter, and other cellulose material, playing an important ecological role in breaking down dead plant matter and recycling nutrients.

Termites undergo gradual (incomplete) metamorphosis: eggs hatch into nymphs that resemble small versions of the adults and molt repeatedly, developing into workers, soldiers, or, in a mature colony, winged reproductive alates. A colony must reach a certain size and maturity, often several years, before it begins producing swarmers annually. A founding pair that survives dispersal becomes the king and queen of a new colony, which may persist and grow for many years.