Napa's beautiful old redwood homes are exactly what drywood termites love. Here's how to tell them from subterranean termites, and why it matters.
Why old Napa homes attract them
Part of what makes Napa Valley so beautiful is the historic housing stock, the downtown Victorians, the Craftsman bungalows, the old stone-and-wood buildings upvalley in St. Helena and Calistoga, many built from aged redwood and old-growth lumber more than a century ago. That same beautiful old wood is exactly what the drywood termite is built to exploit. Unlike its soil-dwelling cousin, the drywood termite needs no ground contact at all: winged reproductives simply fly in on a warm evening and bore directly into dry, sound wood, setting up a colony inside the framing, eaves, fascia, and window and door trim.
So an older Napa home offers a drywood colony everything it wants, decades of seasoned wood with no need for soil moisture. That's why these termites turn up so often in the valley's historic homes, and why owning one of those homes means keeping an eye on the wood.
The signs to look for
Drywood termites are secretive, but they leave a distinctive calling card: small piles of hard, six-sided fecal pellets, often mistaken for sawdust or coffee grounds, that collect on windowsills, floors, or surfaces beneath the infested wood. The termites push these pellets out through a tiny kick-out hole, so a little pile that keeps reappearing after you sweep it up is a strong sign of an active colony overhead.
The other sign is a swarm. On a warm day, winged reproductives leave the colony to start new ones, and you may find them at a window or a pile of discarded wings on a sill. Finding pellets or swarmers means it's time for an inspection to map how far the colony has spread inside the wood, because the extent decides the treatment.
Drywood versus subterranean
Napa has both termites, and telling them apart matters because the treatments are completely different. Subterranean termites live in the soil and must stay connected to it, so they build pencil-width mud tubes up the foundation and crawl-space piers and swarm in spring, usually after rain. Drywood termites live entirely in the wood, leave pellets rather than tubes, and swarm in the warm months. An older home with a raised foundation can host both at once, one in the framing above and one coming up from the soil below.
It's also easy to confuse a termite swarm with flying ants. Termites have a straight, thick waist, straight antennae, and four equal-length wings; ants have a pinched waist, bent antennae, and front wings longer than the back. When in doubt, save a few and have them identified, because the wrong treatment wastes money and leaves the real colony working.
How the wood gets treated
For drywood termites, the treatment depends on how widespread the colony is. A limited, accessible infestation, say a single infested beam or window frame, can often be handled with local wood treatment of the galleries. When the activity is widespread through an older home, whole-structure fumigation is the reliable way to reach every colony in the wood at once, which is a common approach for the valley's historic houses. Subterranean termites, by contrast, are treated at the soil with a liquid termiticide barrier around the foundation.
The first step for either is always an inspection of the slab, crawl space, attic, eaves, and trim to identify which termite is present and how far it has spread. An experienced local exterminator who knows Napa's older homes matches the plan to what's actually found, rather than defaulting to one method for every house.
Call and describe what you're seeing. We'll match you with a Napa-area provider.