The short answer: subterranean termites live in the soil and build mud tubes to reach your house, so they’re treated with liquid termiticide barriers or bait stations in the ground. Drywood termites live entirely inside the wood they eat, need no soil contact and push out piles of tiny, pellet-shaped droppings, so they’re treated in the wood itself, with whole-structure fumigation for widespread infestations or localized spot treatments for small ones. Getting the ID right matters because a soil treatment does nothing for drywood termites, and tenting a house won’t stop a subterranean colony living in the yard. Here’s how to tell them apart and what each treatment involves. For the wider picture on protecting your home, see our pest control guide.
Part of our Pest Control guide →
In this guide
Key Takeaways
- Mud tubes on foundations, piers or walls point to subterranean termites.
- Small piles of hard, six-sided pellets below kick-out holes point to drywood termites.
- Subterranean termites are found in nearly every US state; drywood termites are concentrated in the warm southern coastal belt and the Southwest.
- Subterranean treatment targets the soil (liquid barrier or baits); drywood treatment targets the wood (fumigation, heat or spot treatment).
- Some homes in the South have both, so a professional inspection that identifies the species comes first.
Side-by-Side Comparison
| Factor | Subterranean termites | Drywood termites |
|---|---|---|
| Where the colony lives | In the soil, foraging up into wood | Inside dry wood, no soil contact |
| Moisture needs | High; need contact with damp soil | Low; get water from the wood they eat |
| Key sign | Pencil-width mud tubes | Pellet-shaped droppings (frass) |
| Damage pattern | Galleries follow the soft grain, packed with soil | Clean, smooth galleries cutting across grain |
| Colony size | Often very large | Small, but a house can hold many colonies |
| Where in the house | Sills, joists, framing near ground level | Attics, eaves, window frames, furniture, anywhere |
| US range | Nearly every state | Mostly southern coastal states, Southwest, Hawaii |
| Main treatments | Liquid soil barrier, bait stations | Fumigation, heat, localized wood injection |
How Subterranean Termites Live
Subterranean termites, including the native eastern subterranean termite and the more aggressive invasive Formosan termite, nest in the soil and must stay moist. To reach the wood in your house without drying out, workers build shelter tubes of soil, saliva and droppings up foundation walls, piers, plumbing and even through cracks in slabs. They feed on wood from the inside and pack their galleries with soil, so damaged timber looks layered and dirty when you break into it.
Because they come from the ground, subterranean damage usually starts low: sill plates, rim joists, floor joists, door frames and baseboards near the slab or crawlspace. Anything that holds moisture against the foundation, such as leaking gutters, mulch piled against siding, or wood-to-soil contact at decks and steps, makes an attack more likely.
How Drywood Termites Live
Drywood termites skip the soil entirely. A pair of winged swarmers lands on exposed wood, often in an attic vent, eave or window frame, chews in and seals the entrance. The colony grows slowly inside that one piece of wood and adjoining framing, getting all the moisture it needs from the wood itself. Colonies are small compared with subterranean ones, but a house in a heavily infested area can be colonized by many separate drywood colonies over the years.
Because they don’t need the ground, drywood termites can turn up anywhere: second-story framing, roof sheathing, wood trim, hardwood floors and even furniture moved from one house to another. Their galleries are clean and smooth, with no soil, and they periodically push droppings out of small round “kick-out” holes.
How to Tell Them Apart
Mud tubes vs pellets
This is the single most useful clue. Brown, pencil-width tubes running up a foundation, across a crawlspace pier or along a basement wall mean subterranean termites. Break a section open; if you see small cream-colored insects or the tube is rebuilt within days, it’s active. Small piles of hard, gritty pellets, each about the size of a grain of sand and six-sided with ridges under magnification, mean drywood termites. The pellets often collect on windowsills, floors or attic insulation directly below a pinhole in the wood. For a full checklist of what to look for, see our guide to the signs of termites.
Swarmers and season
Both types swarm, and both leave discarded wings on windowsills. Eastern subterranean termites generally swarm during the day in spring, often after a warm rain. Formosan termites swarm in the evening in late spring and early summer and are strongly attracted to lights. Drywood swarms vary by species and region, with many swarming in late summer or fall, often at dusk or night. Swarmers alone won’t always settle the ID, but where and when you find them adds evidence. Swarmers are also easily confused with flying ants; termites have straight antennae, a thick waist and two pairs of equal-length wings.
Location and damage
Damage near ground level with soil in the galleries points to subterranean termites. Damage high in the structure, in attic framing, window frames or furniture, with clean, smooth tunnels and no soil, points to drywood termites. Formosan subterranean termites can also nest above ground where there’s a steady moisture source, such as a roof leak, which is one reason an expert inspection is worth it in Gulf Coast states.
Where you live
Subterranean termites are found in nearly every US state, with the most pressure in the Southeast and warm, humid regions. Drywood termites are concentrated in a band across southern coastal states, especially Florida, the Gulf Coast, Southern California, Arizona and Hawaii. If you live in the upper Midwest or New England, drywood termites are unlikely unless they arrived in infested furniture or lumber.
Why the Treatments Are Different
Treatment follows biology. Subterranean colonies live in the soil, so the goal is to cut them off from the house or eliminate the colony through the soil. Drywood colonies live in the wood, so the goal is to kill them where they are.
Subterranean termite treatment
- Liquid termiticide barrier. A professional trenches around the foundation and treats the soil, and may drill through slabs, porches and patios to reach soil underneath. Modern non-repellent products are picked up by foraging termites and spread through the colony. Protection typically lasts several years, depending on the product and soil.
- Bait stations. Stations set in the ground around the house at intervals contain cellulose laced with a slow-acting growth regulator. Workers carry it back and the colony declines over months. Baits require ongoing monitoring visits.
- Combination. Many companies spot-treat active areas with liquid and install baits for long-term monitoring.
We compare these two approaches in detail in liquid termite treatment vs bait.
Drywood termite treatment
- Structural fumigation (tenting). The house is covered with tarps and filled with a gas fumigant that penetrates all the wood, killing every drywood colony in the structure, including ones nobody found. You’ll need to leave for a few days. It offers no residual protection, so new swarmers can re-infest later. Our guide on how to prepare for termite tenting covers what to remove and bag.
- Whole-structure heat treatment. The house or a section is heated until wood core temperatures are lethal to termites. No chemicals, but heat can be uneven and may not reach every colony, and heat-sensitive items need removing.
- Localized treatment. Drilling and injecting insecticide or foam directly into infested galleries, or applying borate to exposed wood. Effective when the infestation is small, accessible and well mapped; risky when there may be hidden colonies elsewhere.
- Wood replacement. Removing and replacing a badly damaged board removes the colony inside it.
Borate products applied to bare wood during construction or renovation help deter both types; see our guide to borate wood treatment for termites.
Which Is Worse?
Subterranean termites, as a group, cause more damage nationwide because they’re found almost everywhere and their colonies are large. Formosan termites are especially destructive where they occur. Drywood termites work more slowly, but because colonies are hidden in wood with no mud tubes to give them away, infestations can spread through a house for years before anyone notices. Neither is something to ignore.
Which Should You Choose? A Treatment Decision Guide
- If you find mud tubes or soil-packed damage near the foundation: treat for subterranean termites with a liquid barrier, baits or both.
- If you find pellet piles and the damage is in one window frame or a small, accessible area: ask about localized drywood treatment and a full inspection to rule out other colonies.
- If you find pellets in several rooms, the attic and eaves: fumigation or whole-structure heat is usually the reliable choice.
- If you live in Florida, Southern California or the Gulf Coast and see both signs: you may need both a soil treatment and a drywood treatment.
- If you’re unsure: bag a sample of droppings, wings or insects and have a licensed inspector identify them before agreeing to any treatment.
What a Good Inspection Should Tell You
Before you sign a treatment contract, the inspector should be able to name the species (eastern subterranean, Formosan, western drywood, and so on), show you the evidence that led to that ID, and mark every area of activity on a diagram of the house. Ask what the proposed treatment covers, whether it carries a retreat or repair warranty, how long that warranty runs and what renewal costs. For drywood termites, ask specifically why they recommend spot treatment versus fumigation, and how they’ll confirm there are no hidden colonies. If two companies disagree on the species, get a third opinion. Our guide on how to choose a termite company lists the questions worth asking.
Prevention for Both Types
- Keep mulch, soil and firewood away from siding; leave a few inches of visible foundation.
- Fix leaks, clean gutters and direct downspouts away from the house.
- Ventilate crawlspaces and keep them dry.
- Eliminate wood-to-soil contact at decks, steps, fences and trellises.
- Seal or screen attic vents and keep exterior wood painted or sealed to deter drywood swarmers.
- Inspect used furniture and lumber before bringing it into the house in drywood regions.
- Schedule an annual professional inspection in high-risk areas.
For a broader look at protecting your home and garden from pests, see our pest control guide.
Frequently Asked Questions
Can I treat drywood termites myself?
Small, accessible infestations can sometimes be spot-treated with labeled products injected into galleries, but you can’t easily confirm there are no other colonies. Widespread drywood infestations need professional fumigation or heat.
Does tenting kill subterranean termites?
Fumigation kills termites in the wood of the structure at the time, but it doesn’t treat the soil colony, which can send new foragers back in. Subterranean termites need a soil barrier or baits.
What do drywood termite droppings look like?
Tiny, hard, oval pellets with six flattened sides, ranging from light tan to dark brown depending on the wood. They often pile up like coarse sand or ground pepper below a small hole.
Are Formosan termites subterranean or drywood?
Formosan termites are subterranean. They’re an invasive species in parts of the Southeast and Hawaii, with very large colonies that can also nest above ground where there’s a constant moisture source.
How often should I get a termite inspection?
Once a year is a common recommendation in high-risk regions, and before buying a home anywhere. Many treatment plans include annual inspections as part of the warranty.