Drywood termites are structurally distinct from subterranean species in one critical way: they require no soil contact and no external moisture source to survive. Their entire colony, from the queen to the foraging workers, lives inside the wood they are consuming. This makes the soil-based treatment approaches that work against subterranean termites completely ineffective against drywood termites, and it makes them harder to detect because there are no mud tubes and no connection to the ground that gives the infestation away. Detection depends almost entirely on finding frass, locating kickout holes, or identifying swarm events linked to specific wood in the structure.
Species, Range, and Distribution
The primary drywood termite species damaging US structures are the Western drywood termite (Incisitermes minor), found across California, Arizona, Nevada, and the Pacific Coast states, and the Southeastern drywood termite (Incisitermes snyderi), found along the Gulf Coast and Atlantic seaboard from Florida to Virginia. The West Indian drywood termite (Cryptotermes brevis) is an invasive species present in Florida, Hawaii, and Gulf Coast cities including New Orleans and Houston. It is considered the most destructive drywood species globally because of its tolerance for lower-humidity environments that would limit other drywood species.
Drywood termites are largely absent from the upper Midwest, the northern Great Plains, and New England, where winter temperatures and low humidity are inhospitable to them. Homeowners in warm coastal climates face the highest risk. The risk also extends to wood items that can harbor small colonies in transit: antique furniture, picture frames, wooden structural components in imported goods, and lumber are all documented vectors for introducing drywood termite colonies to new locations and new climates.
Colony Structure and Size
A drywood termite colony is considerably smaller than a mature subterranean termite colony, typically containing a few thousand individuals rather than hundreds of thousands. The colony starts with a single mated pair that finds a suitable crack or crevice in exposed wood, seals themselves inside, and begins producing eggs. Growth is slow: after five years, a drywood colony may contain only a few hundred workers, making early infestations genuinely difficult to detect from damage alone. After ten or more years, a colony may produce secondary reproductives that establish new galleries in adjacent wood, gradually expanding the infestation through a structure over time.
Because colony growth is slow and colony size stays small relative to subterranean species, a single localized drywood termite infestation discovered early is often manageable with targeted DIY treatment. The challenge is that multiple independent colonies can be present simultaneously in different parts of a structure, each having entered through a separate swarm event at different points in time. Identifying all active colonies before treating is important, because localized treatment addresses only the colony it directly contacts.
Identifying Drywood Termites by Their Signs
Frass is the most reliable indicator of active drywood termite activity. Drywood termites push their fecal pellets out of the gallery through small openings called kickout holes, and these pellets accumulate in small piles beneath the hole. The pellets are dry, hard, and hexagonal in cross-section, which distinguishes them from other wood-boring insect frass and from sawdust or debris. They range in color from cream to dark brown or reddish brown, reflecting the color of the wood being consumed.
Frass piles accumulate directly below kickout holes, typically appearing as small conical mounds on floors, windowsills, furniture surfaces, or baseboards. The kickout hole itself is small, typically about 1 mm in diameter, and is often sealed with a thin fecal membrane between clearing events. Probing the wood surface around the hole with a thin wire or awl often reveals the soft, hollow gallery just behind the surface. Locating the kickout hole above a frass pile identifies exactly where the colony is active in the wood, which is the essential starting point for targeted treatment.
Swarms are another identification point. Drywood termite alates are larger than subterranean alates and have a distinctive orange-brown head and thorax with pale or yellowish wings. Swarms for drywood species typically occur on warm evenings in late summer or fall, often triggered by specific temperature and light conditions, and the alates are strongly attracted to artificial light sources. Finding large winged insects near interior light fixtures on a warm evening, with discarded wings accumulating nearby, indicates a drywood swarm from within the structure or from a nearby external colony attempting to establish. The visual differences between termite alates and flying ant alates, including wing size, waist shape, and antenna form, are covered in the termites versus flying ants comparison.
DIY Treatment Options for Drywood Termites
Localized treatment is the appropriate DIY approach when the infestation is confined to identifiable areas of wood and the affected wood is accessible. Two product categories cover the practical DIY options: termite foam injected directly into galleries, and boron-based wood treatments applied to wood surfaces and injected into gallery networks.
Termite foam products use an expanding foam carrier to deliver an insecticide, typically fipronil, imidacloprid, or permethrin, into the gallery network through the kickout hole or through small holes drilled at intervals along the gallery. The foam expands through the gallery on contact, making contact with workers and reproductives throughout the active portion of the colony. Foam is particularly effective in accessible areas such as attic framing, furniture, window frames, door frames, and exposed structural members. The best termite foam guide covers available products, application technique, and the situations where foam is the most appropriate tool.
Boron-based wood treatments, including Tim-bor (disodium octaborate tetrahydrate) and Bora-Care, work through a different mechanism. Boron is a mineral that disrupts termite digestion and kills workers that consume wood treated with it. Borate products dissolved in water penetrate into the wood and remain effective as long as the wood stays dry and unpainted. They are most useful as a preventive treatment on unfinished wood in crawl spaces, attics, and during construction or renovation when wood surfaces are accessible. For established infestations, borate treatment is most effective when injected into the gallery network and applied to all exposed wood surfaces in the affected area at the same time.
When Whole-Structure Treatment Is Required
Whole-structure heat treatment and sulfuryl fluoride tent fumigation are the options for severe or widespread drywood termite infestations where localized treatment cannot reach all active colonies. Both require licensed professional applicators and are not available as DIY options. Heat treatment involves raising the temperature of the entire structure to a level lethal to termites, typically above 120 degrees Fahrenheit for a sustained period. Fumigation uses sulfuryl fluoride gas to penetrate all wood surfaces and voids throughout the structure. Both methods eliminate all active drywood termite colonies in the structure simultaneously, which localized treatment cannot guarantee.
If an inspection reveals multiple active colonies throughout a structure, or if colonies are inaccessible within finished walls or roofing assemblies, professional fumigation or heat treatment is the reliable path to complete elimination. The criteria for deciding between DIY localized treatment and professional whole-structure treatment are covered in the how to get rid of termites overview.
Prevention for Drywood Termites
Drywood termite prevention focuses on sealing potential entry points and treating exposed wood surfaces before an infestation begins. Alates enter structures through gaps in siding, unscreened attic vents, gaps around window and door frames, cracks in eaves and fascia boards, and any exposed unfinished wood surface where a mated pair can seal themselves in and begin a new colony. Sealing these entry points with caulk, installing fine-mesh screens over attic and foundation vents, and keeping exterior wood surfaces painted or finished reduces the number of viable entry sites available to swarming alates.
Preventive borate treatment of attic framing, crawl space lumber, and any unfinished structural wood provides long-lasting residual protection because boron remains in the wood indefinitely as long as the wood is not leached by moisture or painted over. This is particularly practical during renovations when walls are open and framing is exposed. For secondhand wood furniture and antiques, inspecting items carefully before bringing them inside is the most reliable prevention measure, since small drywood termite colonies in furniture can go undetected for years before frass or swarm activity reveals their presence.