Short answer: In Riverside, drywood termites swarm in daylight from July into November, heaviest in September and October on hot, still afternoons. Subterranean termites swarm on warm days after rain, which in the Inland Empire means late fall through spring. A swarm means a mature colony is already nearby, and a pile of identical wings inside the house means it is already in the wood. An inspection starts at $125.
The statewide answer you will see online runs March through October, with the two species jammed together. That calendar is written for the coast. Riverside’s heat pushes the drywood season later and stretches it, and our dry winters shift the subterranean swarms to whenever the rain finally comes. Here is the local calendar and what to do at each point on it.
The Riverside Termite Swarm Calendar
| Months | Who is swarming | What you see |
|---|---|---|
| July to August | Drywood, early | A few swarmers at a window on a hot afternoon. Easy to mistake for flying ants. |
| September to October | Drywood, peak | Piles of wings on sills and floors. The most termite calls we take all year. |
| November | Drywood, tail end | Warm afternoons still produce flights. Cooler nights slow them down. |
| First rain to spring | Subterranean | Swarms from the soil on the first warm day after rain, often out of a crack in a slab or patio. |
The UC Statewide IPM Program states that the most common sighting of drywood termites is flying adults during daytime hours in summer and fall, and places the western drywood termite’s home range along the coast and inland into the deserts east of Riverside. This county sits in the middle of that map.
What Triggers Termites to Come Out?
Heat and, for one species, water. Drywood swarmers leave the colony on hot, still days, which is why September afternoons in Riverside produce them and June mornings on the coast do not. Subterranean swarmers wait for soil moisture. The first warm day after a winter storm sends them up, which in a dry year can mean no visible swarm at all and in a wet year means several.
Both are the same event biologically. A colony that has matured, which for drywood termites takes years, releases winged reproductives to pair up and start new colonies. The swarm you see is the colony advertising that it is old enough to breed.
Do Swarming Termites Mean Infestation?
Swarmers outside mean a mature colony is within flying range, usually a neighbor’s fascia, a fence post, or a dead limb. Swarmers or wings inside the house mean the colony is in your wood. Drywood termites live entirely inside the wood they eat and, as UC IPM puts it, are seldom seen except when they swarm. The wings on your windowsill are the first physical evidence most Riverside homeowners ever get of a colony that has been there for years.
That is the answer to the question. Inside, yes. Outside, not yet, but the inspection is cheap and the alternative is finding out in escrow.
How to Tell Termite Swarmers From Flying Ants
All four wings on a termite are the same length and the waist is thick. Ants have a pinched waist, a smaller back pair of wings, and bent antennae. Swarmers lose their wings within hours, so what you usually find is the wings, not the insect. Termite wings are all identical. Ant wings come in two sizes. Our post on flying ants vs. termites has side-by-side photos.
Should You Spray Swarming Termites?
No, and it is the most common mistake we see. Swarmers do not eat wood and they die on their own within a day. Spraying them kills the messengers and does nothing to the colony that sent them. Worse, it destroys the evidence an inspector uses to find where the colony is: the pile of wings marks the kick-out point, and the direction of the flight points back to the wood.
UC IPM is direct that do-it-yourself treatment of drywood termites is not recommended, because the products that control them are not sold to the public and you cannot see the extent of what you are treating. Vacuum the swarmers, leave the wings, photograph everything, and note which room and what time.
What to Do When You See a Swarm in Riverside
Photograph the wings before you clean them up. Note the room, the window, and the time of day. Check the sills of every south and west facing window, because that is where drywood swarmers head for the light. Then look for the other signs of drywood termites: pellets, kick-out holes, blistered paint.
Then get the wood looked at. A termite inspection starts at $125 for homes up to 2,000 square feet and is done by a Branch 3 licensed inspector. The inspection maps the galleries and decides the treatment. Local treatment starts at $495 per area, orange oil at $695, and full-structure fumigation at $2,395 for homes up to 1,800 square feet. Most Riverside homes we inspect after a swarm never need the tent. The full ladder is on our Riverside termite control page, and the numbers behind each option are in our termite treatment cost guide.
Free limited inspections are available to homeowners who just want to know what they are dealing with. Those are not valid for a real estate transaction. Pricing is effective 2026 and confirmed at inspection.
The wings tell you the colony is mature. The inspection tells you where it is.
Inspection from $125 for homes up to 2,000 square feet. Riverside and Moreno Valley offices, family owned since 2012, license PR 7461, Branch 2 and 3.
Schedule a termite inspection or call (951) 653-7964.
Termite Swarm Questions From Riverside Homeowners
What month do termites stop swarming in California?
Drywood swarms in Riverside taper through November and stop when afternoons cool for good, usually by early December. Subterranean swarms depend on rain and can show up any warm day between the first storm and late spring. There is no month in Riverside when a termite inspection is off-season.
Do most houses in California have termites?
Enough of them that a termite inspection is a standard part of nearly every home sale in Riverside County. The western drywood termite is native to this exact area and was in the dead wood along the Santa Ana River long before there were houses to eat. A swarm is a reason to inspect, not to panic.
What are the first signs of termites in your house?
Wings on a windowsill after a swarm, small piles of hard six-sided pellets below a pinhole in the wood, paint that ripples with no water source, and wood that sounds hollow when you knock on it. Pellets are the sign that confirms drywood termites specifically. UC IPM notes the six-sided pellet shape is diagnostic for the species.
Will termites go away on their own?
No. A drywood colony lives inside the wood and does not need soil, water, or anything from outside. It eats until the wood is gone or the colony is treated. A swarm is the colony expanding, not leaving.
Can you ever fully get rid of termites?
Yes, in a structure. A whole-structure treatment eliminates every colony in the house at once, and a correctly located local treatment eliminates the one you found. What you cannot do is stop next year’s swarmers from landing on the house, which is why an annual inspection is standard after treatment and why the inspection matters more than the product.
