Termite swarming season in Southern California has two parts, and our 13-person team handles both: subterranean termites fly after rain in spring and fall, and drywood termites fly in daylight in summer and fall. A swarm is a mature colony sending out its reproductives. Don't spray it. Bag a sample and call us at (951) 535-4220.
Step outside in Temecula or Murrieta on a warm afternoon a day or two after a good rain and you might see it: a loose cloud of small, dark, winged insects lifting off the lawn by the stem wall, drifting toward the porch light or crawling up the inside of a window. That's a subterranean termite swarm, and it's the one event in a colony's life a homeowner is meant to see. The workers and soldiers stay hidden in the soil and the wood. The swarmers are the announcement.
This post is about the swarm as a season: what's happening, why rain sets it off, how to tell whether it came from your house or the neighbor's, and what to do in the days after. It focuses on the western subterranean termite, which UC IPM calls California's most common subterranean termite. The daytime flight of drywood termites in summer and fall is a different event with a different cue, and our drywood swarming post covers it.
What a termite swarm is and why it happens
A termite swarm is a mature colony releasing its winged reproductives, called alates or swarmers, to mate and start new colonies. It's reproduction. UC IPM explains that a colony spends years growing before it produces swarmers at all, and once it does, it sends them out in flights when the weather is right. The swarmers are weak fliers. They go a short distance, land, drop their wings, pair up and look for a place to start: for subterranean termites that's damp soil against wood, and for drywood termites it's a crack in exposed wood. Almost all of them fail. Birds, lizards, ants and dry air take most of them within a day. The handful that succeed are how a new colony begins in a planter box in Menifee or along a fence line in Wildomar. For you, the flight proves one thing: a colony old enough to reproduce is established in or close to your home.
When do subterranean termites swarm in the Temecula Valley?
After a soaking rain, on a clear day, in spring or in fall. UC IPM's Pest Note on subterranean termites describes the western subterranean termite swarming in daylight on clear days after a soaking rain, in spring or fall, and in Southwest Riverside County the flights follow the storms: a wet week in Murrieta, then a bright, mild afternoon, then swarmers. The season runs until the soil dries out in late spring. In Oceanside, Carlsbad and Vista as much as in Hemet and Perris, the storms set the dates, so there's no single day to circle on a calendar. If you want a rule of thumb for the valley: the first warm, still afternoon after each rain between the first fall storm and the end of spring is a swarm afternoon somewhere in your neighborhood. Drywood termites follow a different cue and fly in daytime in summer and fall with no rain involved at all.
Why do subterranean termites swarm after rain?
Because subterranean termites live in the soil and die quickly in dry air, so the swarmers need the ground soft and the air humid to survive the flight and dig in afterward. Rain gives them both. It softens the soil so a new pair can tunnel in, it raises the humidity so the swarmers don't dry out, and the warm, still day that follows a storm gives them lift. UC IPM ties subterranean swarming to moisture for exactly this reason. It's also why the same colony flies more than once in a season: a flight after the first storm, nothing during the dry stretch, another flight after the next rain. In the Temecula Valley that pattern can repeat several times between the first fall storm and the last spring one. If you noticed a swarm after one rain and then nothing, the colony didn't leave. It's waiting on the next storm, and there's no reason for you to wait with it.
How do I know the swarm came from my house and not the neighbor's?
Where the swarmers came out tells you. Swarmers that appear inside the house, crawling up a window, coming out of a crack between the slab and the baseboard, emerging from a garage wall or piling up in a bathtub, came from a colony that's feeding on your structure. Swarmers you only see outside, lifting off the lawn, the planter or the base of a fence post, could be from a colony in the soil around your home or the neighbor's, and that colony still has your foundation within reach. Look for the exit point. Subterranean swarmers often leave through a small mud-covered slit near the ground, at the base of a stem wall, a garage door jamb or a wood fence post where it meets the dirt. Mark that spot and look for mud tubes within a few feet of it. Either way, call us. A colony in the soil next door has your stem wall within reach, and an inspection tells you whether it's already there.
Signs of subterranean termites besides a swarm
Mud tubes first. Pencil-wide, soil-colored tunnels running up the stem wall, a garage post, a pier in the crawl space or a plumbing pipe at its slab penetration are the signature UC IPM describes, and they're the thing to look for in the week after a swarm. Then soft or hollow wood at ground level: baseboards, door frames and sill plates that give under a screwdriver and reveal muddy, soil-packed galleries inside. Then blistered or bubbled paint low on a wall where the termites have tunneled just under the surface and brought moisture with them. Then doors and windows near the floor that have started to stick. And the quiet signs: damp soil held against the stucco higher than the weep screed, a planter or deck post in contact with the ground, a leaking hose bib or shower pan, which are the conditions that bring subterranean termites to a house in the first place. One sign is worth a call. Two in the same corner of the house are a reason to book soon.
What to do during and after a swarm
During: don't spray. Close the window or door they're coming through if you can, grab a jar or a zip bag and collect a dozen insects, and take photos of where they're emerging. Spray does nothing to the colony in the ground and it destroys the evidence that shows an inspector the exit point. After: leave the wings and any mud at the exit alone, note the date and the rain that came before it, and walk the foundation line looking for tubes. Then phone Jenni on (951) 535-4220 and describe what you saw. Tyler Williams, our termite inspector, checks the accessible areas of the house, the garage, the attic and, where the house has one, the subarea, identifies the species and finds where the activity is. The inspection and estimate are free. Customers choose us for how fast we come out, and swarm season is when that counts, because the next storm is already on the forecast and the colony is already working.
How are subterranean termites treated?
At the ground, where the colony lives. Fumigation is a drywood termite method, for colonies spread through the framing, and it doesn't reach a colony in the soil. Subterranean control takes one of two forms, and UC IPM describes both. The first is a soil treatment around and beneath the foundation that the colony can't cross on its way to the wood. The second is bait placed around the home, which the foraging workers feed on and carry back, so the colony itself is affected rather than just the termites near the house. Along with either, the conditions that drew them in get fixed: the sprinkler hitting the stucco, the soil piled above the weep screed, the planter built against the stem wall, the fence post or deck support set straight into dirt. Which method fits depends on the house and the findings, which is why the inspection comes first. We do the termite treatment in-house, and Dylan Reed is the one who does it. Our termite control page explains what we do for both species.
How to lower your home's risk before the next swarm season
Take away the moisture and the wood-to-soil contact, because those are what subterranean termites follow. Before the winter storms arrive, aim the sprinklers away from the stucco and the stem wall and shorten the run times near the house. Pull soil and mulch down so the weep screed, the metal strip at the bottom of the stucco, is visible all the way around. Get the firewood up on a rack and away from the wall. Fix the hose bib that drips and the shower pan that keeps the slab damp. Check that the downspouts send water away from the foundation and out of the planter against it. Trim the shrubs so the wall can dry. Set fence posts and deck supports on concrete where you can. Then, in the quiet months, have the house inspected. A winter inspection, when the ground is wet and the tubes are fresh, is a good time to catch a colony before it sends its first flight through your kitchen window.
Common questions
What do subterranean termite swarmers look like?
Small, dark brown to brownish-black insects with brownish-gray wings that are all the same length and reach well past the body, which is how UC IPM describes the western subterranean termite. They come out in daylight after rain, often many at once, from a slit near the ground or a crack by the baseboard. To tell them from winged ants, our drywood swarming post has the three checks.
Does a swarm inside the house mean termite damage?
It means a mature colony is established in or next to the house. Whether it has reached your framing, and how far, is what the inspection answers. Swarmers that came out inside the house point to activity in the structure. Swarmers outside point to a colony in the ground close enough to reach your foundation. Either way, the sooner Tyler looks, the better the odds the answer stays small.
What about my kids and pets during termite treatment?
Let Jenni know about children and pets at booking, and ask the technician for the re-entry time on whatever was used. The label on the product sets that time, and every one of our technicians is licensed through the state. Ask about the plan for your house before the work starts.
Will the swarmers come back next year?
Yes, if the colony is left alone. Once a colony is mature it sends out flights every swarm season, so the flight you saw is the first one you noticed and won't be the last. Treating the colony is what stops the next one, and the inspection finds where it is. Call (951) 535-4220.
How long after the swarm do I have before damage gets worse?
The colony has been feeding for years already, so the swarm doesn't start a clock, it reveals one that's been running. There's no need to panic over a week, and there's no reason to wait for the next storm either. Call (951) 535-4220, get the inspection on the calendar, and in the meantime leave the evidence where it is and walk the foundation line for tubes.