Carpenter Ants, Insect Damage
and Tree Stumps Next to the House
Wood-eating insects in the Northwest go where the wood is wet. Russ notes the signs he can see, from a pile of sawdust in the crawlspace to an old tree stump a few feet from the foundation.
Russ wrote up signs of wood-destroying insects, or the conditions that invite them, at 26 recent inspections. Tree stumps close to the house led the list at 10 houses. The rest were ant frass, insect-damaged wood, ant activity inside walls, and damage a report called WDI (wood-destroying insect) evidence.
A home inspection isn’t a pest inspection. These are the signs Russ can see while he’s under and around the house.
What insects show up here
In the Portland metro and SW Washington, carpenter ants and moisture ants are the common ones in reports. Carpenter ants don’t eat wood; they dig nests in it and push out frass. Moisture ants nest in wood that’s already wet and decaying. Subterranean and dampwood termites live here too. Every one of them likes wet wood, which is why insect findings and moisture findings usually show up side by side.
Signs Russ notes
A Portland report found a rim board on an exterior wall with significant insect damage and recommended a licensed pest control professional evaluate and treat it, followed by a contractor repairing the wood. Another Portland report noted what appeared to be carpenter ant frass in the crawlspace and recommended a pest professional find the nest and the extent of any damage.
In Beaverton, ant activity and frass turned up beneath a living room window seat near an outlet and the baseboard. That’s inside a wall. The report sent it to a licensed pest control operator, with a note that nest material can end up in outlet boxes.
Stumps and wood in the soil
Ten houses had a tree stump close to the house. Russ’s report wording: stumps near the home can attract wood-destroying insects, and removal by a qualified person reduces the risk to the structure. A rotting stump a few feet from the foundation is a food source and a nest site right next to the sill plates.
Scrap lumber and form boards left in the crawlspace do the same thing from the inside; the crawlspace wood debris post covers those.
The moisture side
Insects follow water. A plumbing leak in the crawlspace, siding that touches soil, a planter bed against the foundation, or a downspout dumping at the wall all set up the wet wood these insects want. The siding clearance post and the plants against the house post cover two of the usual setups.
Real Inspection Photos
Insect Findings From Russ's Inspections
Insect signs from Russ's recent reports.
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What appeared to be carpenter ant frass at the sill. -
Frass on the foundation wall below framing with active insect damage. -
Insect damage on a roof rafter in the attic. -
A stump close to the house. Stumps near a home can draw insects.
What Russ checks
He looks at visible framing in the crawlspace, basement, garage and attic where accessible, and at the exterior where wood meets soil. He notes frass, insects, damaged wood, stumps near the house and wood debris, and probes wood that looks soft where he can reach it. He doesn’t identify insect species, open walls, or treat anything. He doesn’t offer pest inspections. Signs of insects get a referral to a licensed pest control professional, and damaged framing gets a qualified contractor.
- Look for small piles of coarse sawdust under joists and sills
- Check for winged ants inside in spring
- Note any tree stump near the foundation and any wood scrap on the crawlspace soil
- Look where siding and trim meet the ground outside
- Find any leak or wet wood near the signs
Signs of wood-destroying insects, or the stumps and wood debris that invite them, came up at 26 of Russ’s recent inspections. A pest control professional identifies and treats the insects. Removing stumps and wood near the house and fixing the moisture are what keep them from coming back.
For more on what Russ looks at under the house, see the guide to the crawlspace before you make an offer. To set up an inspection, you can book online.
Wood-Destroying Insect FAQ
