Houston’s biggest termite swarm event happens every May, when Formosan subterranean termites launch into the air by the thousands to mate. If you’ve seen clouds of winged insects around streetlights or piles of translucent wings on your windowsill, you’re witnessing one of the most predictable pest events in the Houston calendar. Here’s what it means, how to tell what you’re looking at, and what to do about it.
When Houston Termites Swarm
Formosan subterranean termites, the most destructive species in the Houston area, swarm on a remarkably consistent schedule. Texas A&M entomologist Robert Puckett puts it simply: the mating window falls the week before and the week after Mother’s Day. That means the peak typically runs from late April through mid-to-late May.
These termites are picky about their flight conditions. They take off on warm, humid evenings with little wind, usually after a few days of rain. In Houston’s climate, that combination is easy to come by in spring. The swarmers are strongly attracted to outdoor lights, which is why you’ll see massive congregations around porch lights, streetlamps, and illuminated storefronts. If your lights are on and your windows are open, they’ll come inside too.
Native eastern subterranean termites also live in the Houston area and can swarm earlier in spring, sometimes starting in February or March during warm spells. Their swarms tend to be smaller and happen during the daytime, making them less dramatic but still worth paying attention to. Drywood termites, less common in Houston, typically swarm in late summer or early fall.
Swarmer or Flying Ant?
Flying ants swarm around the same time of year, and the two insects look similar at a glance. But three physical differences make identification straightforward if you can get a close look at one:
- Wings: Termite swarmers have two pairs of wings that are equal in length. Flying ants have two pairs of unequal length, with the front wings noticeably larger.
- Waist: Termites have a thick, straight waist with no pinch between the thorax and abdomen. Ants have a distinctly narrow, pinched waist.
- Antennae: Termite antennae are straight or gently curved. Ant antennae have a sharp bend, giving them an elbowed appearance.
If you find shed wings on a windowsill, check whether they’re all roughly the same size. Equal-length wings point to termites. You can also collect a few specimens in a plastic bag for a pest inspector to confirm.
What Indoor Swarmers Tell You
Where you find swarmers matters more than how many you see. Swarmers spotted outside your home, buzzing around lights, are a nuisance but not necessarily a sign of trouble. They could have launched from a colony in a neighbor’s yard, a nearby tree stump, or any patch of soil within flying distance.
Swarmers emerging inside your home are a different story. If winged termites are coming out of your walls, baseboards, or flooring, a colony is likely living in or directly beneath your house. These insects didn’t wander in through a door. They tunneled up from an established nest and emerged indoors, which means the infestation has been active long enough for the colony to mature and produce swarmers. That process takes several years for most termite species.
In many cases, you won’t see the swarm itself. You’ll find the aftermath: dozens or hundreds of dead swarmers on windowsills, near light fixtures, or in bathtubs and sinks. Termite swarmers that emerge indoors die quickly because they can’t reach moist soil. You might find only their shed wings, which detach easily and pile up in small drifts near windows and doors.
What to Do During a Swarm
Your first instinct might be to grab a can of bug spray. Don’t bother. Killing swarmers does nothing to address the problem. Every swarmer that emerges indoors will die on its own within hours because it can’t survive without moist ground. The colony that produced those swarmers, potentially numbering in the millions for Formosan termites, continues feeding on wood underground and inside your walls regardless of what happens to the swarmers.
Instead, focus on documenting what you see. Note where the swarmers are emerging from if you can tell, take photos, and save a few specimens. Then get a professional termite inspection. A trained inspector can check for mud tubes along your foundation, probe wood for damage, and use moisture meters to identify areas of active feeding. Most pest control companies offer free inspections, though an independent inspector with no financial stake in selling treatment can provide an unbiased assessment.
Reducing Swarm Activity Around Your Home
You can’t stop a citywide swarm, but you can make your home less attractive to swarmers on those humid May evenings. Turn off unnecessary outdoor lights or switch to yellow-spectrum bulbs, which are less attractive to insects. Close windows and doors at dusk, and make sure your screens are intact. Even a small gap is enough for a swarmer to squeeze through.
Longer term, reducing termite risk in Houston means managing moisture and wood contact around your foundation. Subterranean termites need soil moisture to survive, so fix leaky faucets and irrigation heads near your foundation, grade soil so water drains away from the house, and keep mulch at least several inches from the slab. Store firewood well away from exterior walls. If you have wooden fence posts, deck supports, or landscape timbers in direct ground contact near the house, those are prime entry points for colonies expanding their territory.
Houston’s warm, humid climate and heavy clay soils create ideal conditions for subterranean termites year-round. The swarm you see in May is just the visible moment in a cycle that runs continuously underground. A home that has never been inspected or treated is worth checking even if you haven’t seen a single swarmer inside, especially if it was built on a slab, which is common in the Houston area and gives termites a direct path from soil to framing through small cracks in the concrete.