When most Pittsburgh homeowners think about termites, they picture wood-destroying insects that can cause serious damage to their property. While that’s accurate, not all termites are the same. Understanding the difference between subterranean and drywood termites can help you identify which type you’re dealing with and determine the best course of action to protect your home.
In the Pittsburgh area, subterranean termites are far more common, but drywood termites can occasionally be found here as well, particularly in homes with imported wood furniture or materials from warmer climates. Let’s break down the key differences between these two termite species and what each means for your home.
Where They Live
The most fundamental difference between subterranean and drywood termites is right in their names: where they make their homes.
Subterranean Termites
Subterranean termites live in underground colonies that can contain anywhere from several hundred thousand to several million individual termites. These colonies are typically located in the soil around and beneath your home. The termites build extensive tunnel systems underground and construct mud tubes to travel between their colony and food sources above ground.
Because they live in soil, subterranean termites need constant access to moisture. They can’t survive in dry conditions for long, which is why they build those protective mud tubes when traveling across concrete, metal, or other materials they can’t eat through. These tubes maintain the high humidity levels the termites require.
Drywood Termites
Drywood termites, on the other hand, live directly inside the wood they’re consuming. They don’t need soil contact and don’t build colonies underground. Instead, they establish their nests within wooden structures, furniture, or lumber. A drywood termite colony is much smaller than a subterranean colony, typically containing only a few thousand individuals at most.
Because they live inside dry wood, drywood termites have adapted to survive with very little moisture. They extract the water they need from the wood they eat and from humidity in the air. This means they can infest wood anywhere in your home, from roof rafters to furniture, without needing ground contact.
How They Access Your Home
The way these two termite types enter your home is dramatically different, which affects both how you prevent them and how you treat infestations.
Subterranean Termites
Subterranean termites typically enter homes from the ground up. They build mud tubes from their underground colonies to wooden structures in your home. Common entry points include:
- Foundation cracks and gaps
- Areas where wood touches soil directly
- Spaces around utility lines and pipes entering the home
- Concrete expansion joints
- Hollow blocks in foundation walls
Once they find an entry point, subterranean termites can access virtually any wooden structure in your home by building mud tubes along foundation walls, through crawl spaces, and up interior walls.
Drywood Termites
Drywood termites have a completely different method of infestation. During swarming season, winged reproductive drywood termites fly to new locations and bore directly into exposed wood. They often enter through:
- Attic vents
- Cracks in exterior wood
- Gaps around windows and doors
- Exposed wood trim and siding
- Wooden furniture brought into the home
Drywood termites can also be introduced into homes through infested furniture, picture frames, or other wooden items purchased or moved from areas where drywood termites are more common.
Signs of Infestation
Knowing which type of termite you’re dealing with is important because each leaves different telltale signs.
Subterranean Termite Signs
The most obvious sign of subterranean termites is the presence of mud tubes. These pencil-width tubes are typically found on foundation walls, basement walls, crawl space supports, and other surfaces the termites travel across. Other signs include:
- Soft or hollow-sounding wood
- Damaged wood with a honeycomb pattern inside
- Discarded wings near windows and doors in spring
- Swarms of winged termites emerging from soil near your home
- Sagging floors or ceilings
- Bubbling or peeling paint
Drywood Termite Signs
Drywood termites don’t build mud tubes, so their presence is harder to detect initially. The primary sign of drywood termites is frass, which is the technical term for termite droppings. Drywood termites push their fecal pellets out of small holes in the wood, creating small piles that look like sawdust or coffee grounds. Other signs include:
- Small piles of pellet-shaped droppings below wooden structures
- Tiny holes in wood surfaces (kick-out holes where they push out frass)
- Discarded wings near wooden furniture or structures
- Hollow-sounding wood when tapped
- Visible galleries and tunnels if you break open infested wood
The frass from drywood termites is distinctive because the pellets are uniform in size and have a hexagonal shape when viewed under magnification. This is one of the clearest ways to differentiate drywood termite activity from other wood-damaging pests.
Damage Patterns
Both termite types cause serious damage, but they do it differently.
Subterranean Termite Damage
Subterranean termites typically cause more extensive damage because their colonies are much larger. They eat wood following the grain, creating a honeycomb pattern of galleries separated by thin layers of wood. They avoid eating through the surface layer of wood, which is why damaged areas often look fine from the outside while being completely hollowed out inside.
Because subterranean termites need moisture, they often introduce water into the wood as they eat, which can cause warping, buckling, and what looks like water damage. Structural supports, floor joists, and foundations are particularly vulnerable because they’re closer to the termites’ underground colonies.
Drywood Termite Damage
Drywood termites create smoother galleries that cut across the wood grain. They eat both hard and soft wood portions, creating large chambers connected by smaller tunnels. The galleries tend to be cleaner and have less debris than those created by subterranean termites.
Because drywood colonies are smaller, damage accumulates more slowly. However, drywood termites can infest multiple wooden items throughout your home simultaneously, which can lead to widespread damage over time. They’re particularly problematic in attics, where they can damage roof supports and rafters undetected for years.
Climate and Geographic Considerations
Pittsburgh’s climate plays a significant role in which termite species you’re most likely to encounter.
Subterranean Termites in Pittsburgh
Subterranean termites thrive in Pittsburgh’s climate. The Eastern Subterranean Termite is native to our region and is by far the most common termite problem local homeowners face. Our cold winters don’t eliminate them because their underground colonies stay insulated below the frost line. They become active in spring when soil temperatures rise and remain a threat throughout the warm months.
Pittsburgh’s moisture levels, especially during spring and summer, create ideal conditions for subterranean termites. Homes with drainage problems, damp basements, or crawl spaces are particularly vulnerable.
Drywood Termites in Pittsburgh
Drywood termites are much less common in Pittsburgh because they prefer warmer, more consistently humid climates like those found in southern states. However, they can still appear here, particularly in:
- Homes with imported furniture from southern states
- Properties with architectural salvage or reclaimed wood from warmer regions
- Buildings with wood that was infested before being shipped to Pittsburgh
- Homes near businesses that import wood products
While you shouldn’t assume every termite problem is drywood termites, they’re worth considering if you notice frass or damage in wooden furniture, picture frames, or wood that came from outside the region.
Treatment Differences
The treatment approach for these two termite types is completely different, which is why proper identification is crucial.
Treating Subterranean Termites
Subterranean termite treatment focuses on creating a barrier between the colony in the soil and the wood in your home. Common treatment methods include:
Liquid termiticides: Professional-grade chemicals are applied to the soil around and beneath your home’s foundation, creating a treated zone that kills termites trying to reach your home or return to their colony.
Baiting systems: Stations containing termite bait are placed around your property. Termites feed on the bait and carry it back to their colony, eventually eliminating the entire population.
Direct wood treatment: In some cases, infested wood is treated directly with termiticides or removed and replaced.
Treatment typically requires accessing the soil around your foundation, which may involve drilling through concrete slabs, treating crawl spaces, or trenching around the exterior foundation.
Treating Drywood Termites
Drywood termite treatment focuses on eliminating the termites living inside the wood itself. Methods include:
Spot treatments: Individual pieces of infested wood are treated with termiticides or removed entirely.
Fumigation: For severe infestations affecting multiple areas, the entire structure may need to be tented and fumigated with gas that penetrates wood and kills termites throughout.
Heat treatment: Raising the temperature of infested areas to levels that kill drywood termites.
Wood replacement: Heavily damaged wood is removed and replaced with new, treated lumber.
Drywood termite treatment often requires more targeted approaches since the termites are living in the wood itself rather than traveling from an external colony.
Prevention Strategies
Preventing these two termite types requires different approaches based on their biology and behavior.
Preventing Subterranean Termites
- Eliminate wood-to-soil contact around your home
- Fix moisture problems in basements and crawl spaces
- Ensure proper drainage away from your foundation
- Seal cracks and gaps in your foundation
- Keep mulch and wood debris away from your home’s exterior
- Store firewood at least 20 feet from your house
- Have regular professional inspections
Preventing Drywood Termites
- Inspect furniture and wood items before bringing them into your home
- Seal cracks and gaps in exterior wood
- Apply wood treatments or sealants to exposed wood
- Install screens on attic vents
- Paint or stain exposed wood to seal it
- Be cautious when purchasing used furniture, especially from southern states
- Inspect attics and other out-of-the-way areas regularly
Why Professional Identification Matters
Many homeowners try to diagnose termite problems themselves, but misidentification can lead to ineffective treatment and wasted money. Using a treatment designed for subterranean termites on a drywood termite infestation won’t work, and vice versa.
Professional pest control technicians are trained to identify termite species accurately and choose appropriate treatment methods. At Stewart Termite & Pest Control, we’ve dealt with both subterranean and drywood termites in Pittsburgh homes for nearly 30 years. We know how to spot the subtle differences and implement the right treatment strategy the first time.
The Bottom Line
While both subterranean and drywood termites can damage your Pittsburgh home, understanding the differences between them helps you recognize signs of infestation and take appropriate action. Subterranean termites are the primary concern for most Pittsburgh homeowners, but drywood termites can’t be completely ruled out, especially in homes with imported wood or furniture.
If you notice any signs of termite activity in your home, don’t guess which type you’re dealing with. Contact Stewart Termite & Pest Control at 412-822-7610 for a professional inspection. We’ll accurately identify the termite species, assess the extent of damage, and implement the most effective treatment plan to protect your home.