Hawaii Termite Inspection Guide: Formosan vs Subterranean (Buyer's Edition)
Hawaii has three termite species that matter to homeowners — and they behave nothing like each other. The Formosan colony in your wall is 20x larger and ten times more aggressive than the drywood swarm in your beachside cottage. Here's how to tell them apart, where damage hides in island framing, and what the inspection should actually cover before you close.
The three species you'll encounter
| Species | Where they live | Damage style |
|---|---|---|
| Formosan subterranean Coptotermes formosanus |
Soil contact + above-ground "carton nests" inside walls + wood. Will tunnel up from soil into framing. | Massive. A mature Formosan colony has 1–10 million termites and can hollow a 2x10 floor joist in 12–18 months. Carton nests block walls and trap moisture, accelerating wood rot. |
| Native subterranean Coptotermes vastator, Heterotermes |
Soil-bound — they need moisture from earth contact. | Slower. Mud tubes up the foundation. Damage is steady but recoverable; colonies are smaller (~250k workers). |
| West Indian drywood Cryptotermes brevis |
Above-ground only. They live entirely inside dry wood — no soil contact required. | Localized. They hollow individual boards (a window header, a door jamb) without tubes or signs from outside. Slow but steady. |
How to tell them apart
Frass (droppings)
Drywood termites push dry, hard, hexagonal pellets out of small "kick-out holes" in infested boards. Looks like coarse coffee grounds piling on the windowsill. Formosan and native subterraneans don't produce frass — they reuse it as building material in the colony.
Mud tubes
Subterranean species (both Formosan and native) build pencil-thick mud tubes up foundation walls, post-and-pier supports, and through wall voids. The tubes look like dried clay-colored toothpaste smeared on concrete. Drywood termites never build mud tubes. If you see tubes, it's subterranean — the next question is just whether it's Formosan.
Swarmer wings on the floor
All three species swarm seasonally. After the swarm, the wings fall off and pile near windows, doors, and lights — looking like crispy little fish scales.
- Formosan swarmers are roughly 12–14mm with caramel- colored bodies. They swarm at dusk on warm humid nights, May–July on Oahu.
- Native subterraneans are smaller (~6mm), darker, and swarm in daytime, March–May.
- Drywood swarmers are very small (~5mm), reddish- brown, and swarm in late summer / early fall.
Carton nests (Formosan-only)
The clinching evidence for Formosan: large, papery, brittle nests inside wall cavities, attics, or under floors. Color of dried mud, texture of cardboard, often a few inches thick. If your inspector finds one, you have an established Formosan colony — typically 3–5 years old by the time it's nest-visible.
Where damage hides in Hawaii framing
Hawaii residential framing has predictable termite-vulnerable points that cheap inspectors skip. A real inspection touches all of these:
- Sill plates on slab foundations and post-and-pier caps. First wood contact above grade — Formosan loves this.
- Bottom plates of exterior walls behind landscape mulch beds. Mulch wicks moisture against the framing.
- Window and door headers facing trade-wind weather. Drywood species enter through tiny stress cracks in the trim.
- Roof rafter tails in unscreened soffits. Drywood colonies frequently establish here on older Hawaii bungalows.
- Floor joists above crawl spaces on post-and-pier construction (still common on the Big Island and rural Maui).
- Stairs to second-floor lanai. Stair stringers contact both ground (or near-ground) and the upper structure — a Formosan highway.
- Bath wall framing behind tile. Persistent moisture + unconditioned space = ideal subterranean habitat.
Pulling termite history before you bid
Property Brief surfaces every public-record termite-treatment permit and any prior structural pest inspection report on file for the parcel. Free up to 10 reports/day per IP.
Run a Property Brief →What the inspection should actually cover
A real Hawaii termite inspection runs $250–450 for a single-family home and takes 60–90 minutes. The inspector should:
- Walk the entire exterior perimeter checking for mud tubes.
- Probe accessible wood (sill plates, fascia, deck boards, fence posts) with a screwdriver. Sound, hard wood resists. Soft, hollow wood doesn't.
- Enter the attic and look for carton nests, swarmer wings, frass piles.
- Crawl under post-and-pier homes (or any accessible crawl space).
- Check garage door framing — often the first place subterranean attacks on slab homes.
- Inspect interior baseboards, especially in baths and the kitchen.
- Provide a written report with a diagram showing where damage was found, what species, and a recommended treatment scope.
A 20-minute "drive-by" inspection where the guy walks around the outside and signs the form for $150 is not an inspection. Insist on the full protocol or hire a different company.
Treatment options at a glance
- Tent fumigation (Vikane gas): the only treatment that reliably kills established drywood colonies through the entire structure. $2–4k for a typical Honolulu single-family. Plan to be out 3 days.
- Termidor / Premise soil treatment: non-repellent liquid injected around the foundation perimeter. Works on subterraneans (Formosan + native) by transferring through the colony. $1.5–3k.
- Sentricon / Trelona bait stations: in-ground stations that subterranean foragers bring back to the colony. Slow (12–18 months for full kill) but effective and ongoing monitoring. ~$1.2k initial + $400/yr.
- Spot localized treatment: direct injection on identified drywood damage. Cheap ($150–400) but only works on isolated infestations — not effective once the colony has spread.