Is Termite Damage Old or Active? How to Tell the Difference

Half the termite calls we take in the San Gabriel Valley start the same way: "the previous owner said this was treated." Old damage does not need treatment. An active colony does. Telling them apart is most of what a termite inspection is for, and the honest starting point is that the damage itself cannot tell you.

Why the damage alone cannot answer it

Termite galleries do not heal. A board hollowed out in 1998 looks the same today, and a pellet pile can sit inside a wall void for years and spill out the day someone hangs a picture. The University of California's pest note on drywood termites is blunt: it is not possible to determine from fecal pellets alone whether an infestation is currently active, or how extensively the wood is infested. Pellet color does not help either; it tracks the wood the termites ate, not the date.

The signs that mean active, now

The signs that usually mean old

• Dry, brittle tubes that stay broken for weeks.
• A pellet pile that never grows once the spot is cleared and dated.
• Galleries with no termites in them, packed with old pellets and dust.
• Damage that has been painted over more than once, with no fresh pellets at the surface.
• Plugged drill holes from a prior treatment, and a filed report to match. The Structural Pest Control Board keeps inspection and completion reports on file and can provide copies for a property, so a prior treatment can be checked rather than taken on faith.

None of these is proof on its own. Termites can abandon one gallery and keep working ten feet away, which is why "old" is a conclusion we reach after the checks above, not a glance.

What happens on the inspection

Under California Business and Professions Code section 8516, no company may issue an opinion about the presence or absence of wood-destroying pests until a licensed Branch 3 inspection has been made, and the report is filed with the Board. On ours, we sound and probe accessible wood, look for live insects, tape and date pellet piles, break a section of any tube we find, and note what we could not reach. Damage goes on the report as a finding either way. Whether the recommendation is treatment or repair only depends on whether activity is confirmed. Our guide to reading a California termite report explains the sections.

Drywood vs. subterranean changes the test

Drywood termites live entirely inside the wood, so the pellet recheck is the test that matters. Subterranean termites come from the soil and are driven by moisture; a tube can be abandoned when a leak is fixed and reoccupied when the next one starts. For them the tube test plus a look at the moisture source tells the story. Our termite evidence guide shows what each kind of evidence looks like.

What to do with old damage

If no activity is confirmed, no treatment is warranted. The wood may still need repair for structural reasons, and the area should be rechecked at the next annual inspection because the conditions that invited termites once are usually still there. If activity is confirmed, a localized treatment handles limited drywood activity and bait stations handle a soil colony; widespread activity is a fumigation conversation.

Sources

• UC IPM Pest Notes: Drywood Termites (University of California)
• UC IPM Pest Notes: Subterranean and Other Termites (University of California)
• California Business and Professions Code § 8516 (WDO inspection before any opinion or work; reports filed with the Board)
• California Structural Pest Control Board