The short answer: if you find mud tubes running up a foundation or into the framing, you have subterranean termites coming from the soil. If you find small piles of pellet-like frass that look like sawdust or coffee grounds, you have drywood termites living inside the wood itself. The two species live differently and are treated differently — subterranean work usually means soil and localized treatment, while a widespread drywood infestation may call for tent fumigation. Knowing which you have is the first real decision.
What is the difference between the two?
Subterranean termites nest in the soil and need moisture, so they build the mud tubes you see to travel between the ground and the wood without drying out. In the Bay Area’s irrigated clay soils they stay active roughly year-round, and they swarm after the first heavy fall rains. Drywood termites skip the soil entirely — they live inside dry structural wood and push their droppings out through small kick-out holes, leaving the tell-tale frass. Drywood infestations favor older homes; pre-1960 houses are the common target.
Dealing with this right now in the San Jose area?
A licensed operator can inspect and quote before any treatment.
| Clue | Subterranean | Drywood |
|---|---|---|
| Where they live | In the soil, travel to wood | Inside the wood itself |
| Main sign | Mud tubes on foundation or framing | Pellet-like frass (sawdust look) |
| Moisture need | High — needs soil contact | Low — thrives in dry wood |
| Swarm timing | After first heavy fall rains | Warm weather, often late summer |
| Typical home | Any, especially slab and crawlspace | Pre-1960 homes |
How are San Jose homes affected differently?
Housing stock decides a lot. Pre-war bungalows in Willow Glen, Naglee Park, and the Rose Garden are prime drywood candidates because of their age and exposed older wood. Post-war raised-foundation tract homes in East San Jose give subterranean termites easy soil-to-wood access through the crawlspace, and slab-built Eichlers can hide subterranean activity at the slab edge where framing meets concrete. The irrigated clay common across the valley keeps subterranean colonies damp and busy far longer than drier regions.
Tent fumigation or localized treatment?
This depends on the species and how far it has spread. Subterranean termites are usually handled with soil and localized treatments targeting the colony’s route into the structure. Drywood termites in one beam or window frame can often be treated locally, but when they are established in many parts of the structure, tent fumigation is the method that reaches every gallery at once. On statewide estimates, tent fumigation runs roughly $2,200 to $5,500 — treat that as a statewide guide figure, not a quote, because square footage and construction drive the real number.
What should I do if I think I have termites?
- Photograph the mud tubes or frass and note exactly where you found them
- Do not knock down a mud tube — it helps the inspector confirm active travel
- Check swarm timing: subterranean swarms track the first heavy fall rains
- Get a licensed Branch 3 WDO inspection to confirm species and extent
- Match the treatment to the finding — localized for contained, fumigation for widespread drywood
The first-rain swarm: what San Jose homeowners see
The single most common way people discover subterranean termites in the valley is the fall swarm. When the first heavy rains land — usually sometime between late October and December depending on the year — the moisture and the drop in pressure trigger winged reproductives, called alates, to pour out of mature colonies to start new ones. Indoors, that looks like dozens or hundreds of dark, winged insects at a window or around a light, often followed by a scatter of discarded wings on the sill once they land and shed them. A swarm inside the house is not a nuisance to sweep up and forget — it is strong evidence of an established colony in or right against the structure, because the alates came from somewhere close.
Drywood termites swarm on a different schedule, typically in warm, dry weather in late summer and early fall rather than with the rains, and in smaller numbers. Either way, the wings on the windowsill are often the first and only early warning a homeowner gets, since both species do their real damage out of sight inside the wood.
What tent fumigation actually involves — and its limits
Tent fumigation sounds dramatic, and the prep is real, so it is worth knowing what the week looks like before you commit. The structure is sealed under tarps, a fumigant gas is introduced to penetrate every gallery in the wood, the home is held, and then a licensed operator aerates and clears it before anyone re-enters. You and your pets are out of the house for roughly two to three days, and you prepare by bagging or removing food, medicine, and some plants per the operator’s instructions. The payoff is reach: fumigation is the only method that treats drywood termites throughout an entire structure at once, including galleries no one can see.
The honest trade-off is that fumigation leaves no residual protection. The day the tarps come off, the home is clear — but nothing stops a new drywood swarm from re-infesting down the road, which is why exclusion and periodic inspection still matter afterward. For a problem confined to one accessible beam or window frame, local treatment such as a spot application or heat can solve it without tenting the whole house. That is the real decision the inspection settles: is the infestation contained, or spread widely enough that only a tent reaches all of it. On statewide estimates fumigation runs roughly $2,200 to $5,500 and local treatments far less — but those are guide figures, not quotes, and the inspection drives the number.
Protecting your home between inspections
Most of what invites termites is moisture and wood that touches soil, and both are things a homeowner can manage. Subterranean termites especially need damp conditions and a soil-to-wood bridge, so cutting those off makes your home a harder target.
- Keep irrigation and sprinklers from spraying the foundation and siding
- Fix plumbing and roof leaks promptly — damp framing is an open invitation
- Break earth-to-wood contact: no soil, mulch, or firewood stacked against siding or posts
- Grade soil so water drains away from the foundation, not toward it
- Store firewood and lumber off the ground and away from the house
- Get a licensed WDO inspection periodically, not only when you are selling
Catching termites before the swarm
Because termites work out of sight, the homeowners who avoid the worst damage are the ones who notice the quiet early signs rather than waiting for a swarm or a soft floor. For subterranean termites that means periodically checking the foundation perimeter, the crawlspace, and any spot where wood meets soil for the pencil-width mud tubes they build to travel — a tube is their lifeline, and its presence is a direct tell. For drywood termites it means watching for the small, uniform, pellet-like frass that collects below a kick-out hole, often on a windowsill, baseboard, or the garage floor beneath a beam. Tapping suspect wood that sounds hollow, or finding paint that is blistered or bubbling over a gallery, is another early flag. None of these replace a licensed inspection, but spotting them early is what turns a contained spot treatment into the likely outcome instead of a full tent.
In the valley the single best habit is a WDO inspection on a regular cadence — not only when a sale forces one — because the clock on termite damage runs for years before it shows, and the earlier a colony is caught the cheaper and less invasive the fix.
Termite decisions are expensive to get wrong, which is why the species and the spread have to be confirmed before anyone recommends a tent. Budget Pest Control is licensed with the California Structural Pest Control Board (Company Reg. #5209) and has inspected and treated Bay Area homes since 2007. If you have found mud tubes, frass, or a swarm — or you need a WDO report for escrow — call (209) 563-1650.