Western Subterranean Termites

This is a caste system, not a straightforward life cycle. Like all termites, this species goes through incomplete metamorphosis, so there is no pupal stage. Eggs hatch into an undifferentiated immature that sources still call a larva despite the lack of true larval metamorphosis. From there, individuals branch into workers, soldiers, or nymphs, and only the nymph path leads toward winged alates. Other individuals, called supplementary or neotenic reproductives, can step in to replace a king or queen that dies, keeping the colony going. Founding colonies grow slowly. At the end of its first year, a new colony may have grown to only about 75 individuals, and very few of the pairs that fly each year ever successfully found a colony that survives to maturity. A mature colony, by contrast, can run into the hundreds of thousands of individuals, and a single home's footprint can sit above several separate colonies at once. Once established, a queen can lay eggs at a rate the sources describe as sometimes thousands in a single day. Kings and queens can live a decade or more, while individual workers live one to several years. One more thing: recent genetic work has found that what gets called the western subterranean termite is technically a species complex, a group of several genetically distinct lineages rather than one uniform organism, some of which have not yet been formally named. It is a research detail more than a field-identification one.

Almost impossible to tell apart

The honest headline: this species and the eastern subterranean termite are almost impossible to tell apart by looks. Same genus, same caste appearance, same general size range. A size or color difference between the two species circulates on some websites, but it does not trace back to any university extension or federal source. If you need to know which one you have, the answer is range and swarm season, not what it looks like under a hand lens.

Wing venation names the genus

Wing venation is the tell that matters, and it separates this genus from other termites, not this species from its eastern cousin. Alate wings are brownish-gray with only a few hairs, and two dark, heavily sclerotized veins run along the base of the wing. That sparse-to-hairless wing surface is the same check used to rule out the Formosan subterranean termite, whose alate wings are covered in fine hairs.

Soldier head shape

It is the other genus-level tell. A rectangular, narrow, pale to light-brown head with no eyes and long, curved, toothless mandibles marks this as a Reticulitermes soldier, as opposed to the oval-headed soldier of a Formosan colony. A small gland opening called a fontanelle sits on the head of soldiers and alates, though it may be indistinct.

Sizes, for reference

Alates run about 0.38 to 0.4 inch (around 10 mm) including wings, workers about 0.18 inch (roughly 4.5 mm) and are often compared to a grain of rice, and no published source gives a soldier body length.

Termite or flying ant

Check the waist first: a termite is the same width end to end, an ant has an obvious pinch. Then the wings: a termite's four wings are all the same length and shape, an ant's front pair is noticeably longer. Then the antennae: straight and beaded on a termite, elbowed on an ant. California's own extension program frames this exact question, termite or ant, as one of the most common calls homeowners make.

Pacific dampwood termite

It is a very different-looking insect sharing the same region. Its reproductives can exceed an inch long including wings, roughly two and a half to three times the length of a western subterranean termite alate, and it needs no soil connection at all, infesting wet or damp wood directly. It is described as the largest termite species found in the Pacific Northwest.

Drywood termites in California

Drywood termites are a real possibility in California, less so in the Pacific Northwest. In California, drywood termites are most common in the south but also occur along the coast and in the Central Valley, and in the Pacific Northwest there is no evidence the species has become established. Either way, the distinguishing test is the same one used for other subterranean-versus-drywood comparisons: soil tube presence and the shape of any droppings, since drywood termites need no soil contact and nest directly in dry wood.

Two other genera, other schedules

Two other subterranean genera turn up in parts of this range and swarm on a different schedule entirely. Heterotermes aureus, the most destructive subterranean termite in the Sonoran Desert portion of southeastern California, flies in the early evening and is drawn to light. The Formosan subterranean termite, established in a small area near San Diego, also swarms at dusk under lights and has the hairy-winged tell noted above. A native relative, Reticulitermes tibialis, overlaps this species' range in parts of Nevada and Idaho, but no published source gives a specific field tell separating the two, so the two cannot reliably be told apart by eye.

Termites are social cockroaches

A true thing worth knowing: termites are taxonomically social cockroaches. They sit in the order Blattodea alongside cockroaches under current taxonomy, though some sources still use the older name Isoptera. It is the same reclassification that applies to every termite, not something specific to this species.

Swarms of winged reproductives

Primarily in fall, after the first soaking rain. A swarm overhead does not automatically mean a house is infested, but winged termites emerging directly from the ground or from wood at the property is clear evidence of a mature colony nearby.

Shelter tubes

Shelter tubes, the most commonly seen evidence of an infestation. Built from saliva mixed with soil and bits of wood, and sometimes constructed right over a concrete foundation to bridge from soil to wood. Researchers describe four distinct types: working tubes connecting soil to wood, exploratory or migratory tubes that never reach wood, drop tubes running from wood back to soil, and swarm tubes built for reproductives to emerge from.

Darkening or blistering wood

Darkening or blistering of structural wood, typically thin at the surface and easily punctured with a knife or screwdriver, with the outer shell often left looking intact.

Workers visible in a broken tube

Live workers and soldiers visible if a tube is broken open.

Damage that follows the grain

Damage that follows the wood grain, hollowing the softer springwood and leaving the harder summerwood, a pattern distinctive enough on its own to positively identify subterranean termite activity rather than some other cause.

No reliable sound and no smell

No published source attributes any audible or odor-based sign to this species.

Keep a 12-inch barrier

Use smooth concrete, coarse sand, or other inorganic material between the soil surface and any structural wood under a building.

Ventilate and dry the substructure

Keep substructures ventilated and dry. Moisture is what draws this species into wood in the first place.

Remove wood piles and scrap

Remove wood piles, untreated fence posts, and buried scrap wood near the structure. They function as food and as a bridge for a colony even before it reaches the house.

Repair cracks and leaks at once

Repair foundation cracks, plumbing leaks, faulty grades, and exterior wood defects immediately. These are the entry points that let termites bypass any barrier that has been put in place.

Use resistant wood or footers

Use termite-resistant wood or concrete footers for any structural element that has to touch soil, and finish exterior wood with sealants or paint.

Watch stucco that runs to grade

Watch stucco siding that runs down to the ground. It can let termites travel unseen between the stucco and the foundation, a detail worth paying particular attention to in California.

Call for a tube or a swarm

Call a professional if a shelter tube shows up on an interior or exterior wall, or if thousands of flying insects suddenly appear in a bathroom or kitchen. Those are the two moments most homeowners actually notice a problem.

Inspect every three to five years

A standing inspection every three to five years is the baseline recommendation, regardless of whether anything looks wrong, especially for a home with any prior termite history.

This is not a DIY pest

This is not a do-it-yourself pest. Retail termite pesticides are not effective against an established colony, and in California all of the products that actually work are restricted to professional, licensed use.

No need to panic over a swarm

There is no need to panic over a swarm. A colony takes roughly a year to grow to only about 75 individuals and years more to mature, so an active infestation represents years of unseen growth rather than a sudden event. Note the exact location of any swarm for an inspector instead of rushing a decision.