Subterranean termites are the most common pest termite in California, and three of the twenty-three termite species in the state are pests. Termite work begins with an inspection regulated by the Structural Pest Control Board. Local species and local swarm timing are not documented on this site, so they are not stated here.
Key takeaways
- Subterranean termites are the most common pest termite in California, and they are found throughout the state.
- Dampwood termites are more likely on the coast, drywood termites occur across most coastal and Central Valley areas, and the local species for Anderson Valley has not been confirmed.
- Swarms often follow the first fall rains, but no North Coast swarm calendar has been established for this area.
- A termite inspection should produce a written report, and treatment should be scoped from that report.
- The Structural Pest Control Board licenses structural pest control, and termite inspection and treatment are part of that regulated work.
Which termites are the pests in California?
Subterranean termites are the most common pest termite in California, and three of the twenty-three termite species found in the state are pests. Knowing which species is involved is the first step in any termite job.
Termites are social insects that feed on cellulose, which is the material in wood, paper and some other building materials. Not every termite in California is a pest of buildings, and the species that matter most to a homeowner are the ones that find their way into structures. Among those, the subterranean termite is the most common pest termite in the state, according to the University of California's Integrated Pest Management Program.
Subterranean termites live in the soil and need moisture to survive. They reach wood through mud tubes built over foundations, piers and sills, and they can work unseen for a long time. Their presence is often found by a technician looking at the lower part of a structure, or by a homeowner who notices blistered paint, sagging floors or small piles of pellets near a door.
Drywood and dampwood termites live inside the wood they feed on and need less contact with soil. Their pellets can be found on window sills or below infested timber. The identification of the species changes the treatment, which is why a technician should name the termite before recommending work, rather than offering one method for every case.
What damage do termites cause to a house?
Termites feed on the structural and decorative wood in a building, weakening it from the inside. Damage is often hidden behind finishes, so a visible sign usually means the problem is already more advanced than it looks.
The structural timber of a house, including sills, joists, studs and subfloor, is the main concern. Termites hollow out wood along the grain and leave a thin shell that can look sound from outside. A floor that feels soft, a door that sticks for no clear reason or a crack that appears in plaster can all be signs that the timber has been working on for some time.
Termites do not eat through masonry, but they can use any gap, expansion joint or pipe penetration to reach timber. A house with wood in contact with soil, or with a moist crawl space, gives them an easy route. Keeping wood off the ground and reducing standing water near the foundation are standard preventive steps, and they are worth discussing with a technician.
Carpenter ants are often confused with termites. They invade wood to make nests and hollow it out, but they do not eat it. The distinction matters because the treatment differs, and a technician should confirm which insect is present before work begins.
Does the coast or the inland side change the termite risk?
Yes, somewhat. Dampwood termites are more likely in the cool, humid coastal areas, while drywood termites are found along most coastal regions and the Central Valley. The climate on each side of the county differs, so local advice should be based on the site.
The University of California's Pest Notes say dampwood termites are most often found in cool, humid areas along the coast. That makes them a more likely concern for coastal homes than for inland ones, but it is a general statement about where they are most often found. It is not a survey of the coast, and it is not a finding for any particular house.
Drywood termites occur along most of the coastal regions and in the Central Valley, though they are most common in southern California. Subterranean termites are common throughout the state. The point for a homeowner is that a single species is not confined to one side of the county, and the risk on a given property depends on its construction, its moisture and its surroundings.
Summer conditions also differ between coast and inland. Coastal summers are usually cooler and often foggy in the mornings, while inland valleys run much warmer in summer. Those differences affect how a building dries out and how the soil behaves around it. They are a reason to ask a technician about the specific site rather than to assume one answer for the whole county.
Why do termite swarms appear after rain?
Termite swarms often follow the first fall rains, when winged reproductives leave colonies to start new ones. No North Coast swarm calendar has been established for this area, so the timing cannot be assumed for a specific property.
Winged termites, often called swarmers or alates, leave a mature colony to mate and start a new one. Their flights are often triggered by warm, humid conditions, and the first fall rains are a common time for swarming in many parts of the state. Seeing a swarm, or the discarded wings left on window sills and near lights, is a sign that a colony is nearby.
A swarm does not mean the house is infested, and an absence of swarms does not mean it is safe. A swarm can come from a colony in the soil or in a tree near the building, and it can happen even when the structure is sound. The swarm is a signal to get an inspection, not a diagnosis in itself.
The University of California's guidance says swarms often follow the first fall rains, but no timetable has been set for the North Coast, and this site does not publish one. A swarm observed in Anderson Valley should be reported to a technician, who can judge what it means for the building and where the colony is likely to be.
What does a termite inspection involve?
A termite inspection looks at the foundation, sills, subfloor, crawl space, attic and any wood in contact with soil. It should end in a written report that says what was found and what treatment, if any, is proposed.
The inspection begins outside, where a technician looks at the foundation, the soil line, the mud tubes and the moisture around the house. Inside, the technician checks the sills, joists, subfloor and any area with a history of leaks. A crawl space or basement is usually the most important part of the inspection, because it is where subterranean termites tend to work first.
The report is the document that matters. It should set out what was found, where it was found, which species was identified and what the technician recommends. It should also say what the inspection could not see, because a sealed wall or a finished floor limits what can be checked. A report that says everything is fine without describing the areas that were looked at is not a full report.
In California, termite inspection and the Branch 3 work that follows are regulated by the Structural Pest Control Board. Ask the technician which branch the work falls under and check the license number with the board. The regulated inspection is the basis for any treatment decision, so keep the report with your records.
What about building new or rebuilding?
Pre-construction termite treatment is done before a building is finished, and it is scoped against the design, the foundation and the build schedule. Its price depends on the site and should be confirmed in writing before the work begins.
A new structure or a rebuild has no existing infestation to find, so a pre-construction treatment is aimed at keeping termites out. Its scope depends on the foundation type, the way the slab or footings are poured, the position of the utilities and the timetable of the build. The treatment has to fit the work that is still to be done, which is why the timing matters.
Ask the provider to show which parts of the structure are covered and when the treatment is applied in the build sequence. Ask whether the plan changes if the design changes, because a late change to the foundation or to a crawl space can alter the work. A written scope protects both the builder and the homeowner.
Local construction patterns in Anderson Valley and the surrounding area are not documented on this site, so this guide does not assume what a particular build will involve. The specific details belong in the scope of the work, and that is what the quote should describe.
What treatment options do technicians use for termites?
Termite treatment usually means either a liquid treatment applied to the soil around a structure or a bait system placed in the ground. The right method depends on the species, the structure and the report.
Liquid soil treatments create a barrier at the foundation and can be applied to the soil before construction or to an existing structure. Bait systems are placed in the ground around a building and draw termites in over time. Each approach has its place, and a technician should explain why one is recommended over the other for a particular building.
Whatever the method, the work should be described in the quote and the report. Ask how the treatment will be monitored, how often the technician will check it and what happens if termites are found again. A treatment that is not monitored is a treatment whose results nobody can see.
Repairs to damaged wood are a separate question. Where timber has been weakened, the structure may need repair or replacement, and that work is for a qualified builder or a regulated repair contractor. Ask the technician whether the report includes repair recommendations, and keep those separate from the treatment price.
Frequently asked questions
Are termites found in Mendocino County homes?
Termites are found throughout California, and subterranean termites are the most common pest termite in the state. The specific species and how common they are in Anderson Valley have not been documented here, so an inspection is the way to know about a particular house.
How can I tell termites from carpenter ants?
Termites feed on wood, while carpenter ants hollow it out to nest without eating it. A technician can confirm which insect is present, and the treatment depends on the answer, so ask before any work begins.
Should I expect termite swarms after the first rain?
Swarms often follow the first fall rains in many parts of California, but no North Coast timetable has been set. A swarm is a reason to have the building inspected, not proof of an infestation or a clean bill of health.
What should a termite report include?
It should name the species, list the areas inspected and the areas that could not be seen, describe what was found and say what treatment, if any, is proposed. A report without those details is incomplete.
Sources
- University of California Statewide Integrated Pest Management Program - Pest Notes
- California Structural Pest Control Board - How do I get a license
This guide is general information for Mendocino County homeowners, not a substitute for an on-site inspection. Prices are estimates. See our disclaimer.