When termites swarm in Southern California: a season by season guide for Long Beach

Why termites swarm at all

Swarmers, also called alates, are the reproductive caste of a mature colony. A colony raises them for months, then releases them on a day when temperature, humidity and light line up. They fly briefly, drop their wings, pair off and try to start new colonies. Most fail, but enough succeed that a neighborhood with older wood framing stays under steady pressure year after year.

A swarm from inside the house means a mature colony is already in the structure, usually several years old. A swarm you see outdoors, on a fence or a neighbor's eave, means colonies are close by and your wood is a landing target.

Winter, December through February: quiet but not idle

Winter is the slowest stretch for swarms in Long Beach, though colonies keep feeding because our winters are mild. Western subterranean termites in the soil benefit from winter rain, which moistens the ground and helps colonies grow toward the spring flight.

This is a good season for the work that swarms tend to interrupt. Crawlspaces are cooler and easier to work in, attic temperatures are bearable, and there is time to fix earth-to-wood contact, leaky hose bibs and clogged gutters before spring. If you saw drywood swarmers last fall and never dealt with them, winter is a sensible time to get an inspection and plan treatment calmly.

Spring, February through May: subterranean flights after rain

Western subterranean termites are the spring swarmers. The classic pattern is a warm, still, sunny day that follows a rain, often in the late morning. The swarmers are small and dark, nearly black, with pale translucent wings, and they come up through cracks in a slab, gaps at baseboards, bathroom plumbing openings or the soil along the foundation.

Indoors you will often find them near the ground floor: around a tub, at a sliding door threshold, in a garage along the slab edge. Outdoors you might see them rising out of a lawn, a planter bed or a gap between the driveway and the house.

A spring swarm inside a slab home in Los Altos or a raised bungalow in Rose Park points strongly toward subterranean termites and a soil-based treatment plan, such as a liquid barrier or a bait system.

• Look for: small dark swarmers, low in the house, after rain
• Check for: mud tubes on the foundation, slab cracks, wet crawlspace soil
• Likely next step: subterranean inspection and a soil treatment plan

Early summer, June and July: the lull and the buildup

Early summer often brings marine layer mornings that keep the coast cool, and swarm activity drops off for most species. Drywood colonies are busy raising the alates that will fly later in the year, and you may notice more pellets appearing as activity picks up in warm attics.

This is a good window to look for drywood clues before the fall flight. Check the tops of garage walls, attic floors near the eaves, the sills of west-facing windows and the space under exposed rafter tails. A fresh pellet pile in June or July often marks a colony that will swarm a few weeks later.

Late summer and fall, August through October: drywood season

This is the season Long Beach is known for. Western drywood termites typically swarm on warm, sunny afternoons from roughly August into October, and the first heat wave of late summer often sets off a big flight across many neighborhoods at once. Swarmers are slightly larger than subterranean ones, with a reddish brown head and smoky dark wings.

They come out of kick-out holes and small openings in the wood itself: attic vents, eaves, window frames, door trim, built-in cabinets and occasionally furniture. In Bluff Park, California Heights or Belmont Heights it is common to find swarmers on the inside of upstairs windows or collecting around an attic hatch. Downtown and in Alamitos Beach, residents of older courtyard buildings sometimes see them on several floors at once because the colony is in shared framing.

Pacific dampwood termites can also fly in late summer and fall, often near dusk and drawn to lights. They are much larger, and around Naples and the marinas they point to wet wood in docks, decks or seawall lumber.

What to do in the first hour after a swarm

Swarmers themselves are harmless to people and do not eat wood. Most die within hours indoors because they dry out. The goal now is to keep evidence and avoid making the source harder to find.

Avoid spraying the area with insecticide or sealing up the openings they came from. Sealing the hole hides the colony without killing it, and the next swarm will simply find another exit. A vacuum is fine for cleanup once you have a sample. If you want someone to look at what you have, a person answers at (562) 636-0445 around the clock.

• Collect a few swarmers and wings in a sealed bag or on clear tape
• Photograph where they gathered and note the time and the weather
• Look above and around that spot for pellets, small holes or mud
• Then vacuum the rest and keep pets away from the pile

How swarm timing shapes the treatment calendar

Swarm season does not set the treatment date, but it affects planning. Fumigation can be done any time of year, and many homeowners prefer to tent soon after a fall swarm reveals how widespread the problem is. Local drywood treatments are easiest when kick-out holes and pellets are fresh and the colony locations are clear.

Subterranean treatments go best when the soil is not saturated, so a liquid application right after a heavy storm sometimes waits a few days. Bait systems can be installed any time and keep working through the following swarm seasons. Either way, a swarm is a signal to act within weeks, not a reason to panic overnight.

Reader questions