If you clean up the little pellets and they come back a few days later, that's the most important clue in the whole situation. Here's what it's telling you.
The call usually goes like this: "I keep finding these little pellets on the windowsill. I vacuum them up, and a few days later they're back." The recurrence is the part that matters most — and it's the part people tend to underweight. Those pellets are almost always frass, drywood termite droppings, and the fact that they keep reappearing after you clean them up tells you the colony producing them is still there, still active, and still working.
Cleaning up frass doesn't get rid of termites any more than emptying a trash can gets rid of whatever keeps filling it. Here's what you're actually finding, and what the recurrence is telling you.
What You're Actually Looking At
Drywood termite frass has a specific look, and once you've identified it correctly you won't mistake it again.
| What it is | Appearance | What it means |
|---|---|---|
| Frass (drywood droppings) | Small oval pellets ~1mm long, six-sided/ridged, uniform tan-to-brown, no odor | Active drywood colony nearby |
| Sawdust | Irregular, fibrous, powdery, inconsistent size | Wood-boring beetles, or recent cutting/drilling |
| Rodent droppings | Larger (4–8mm), dark, tapered ends | Rodents — unrelated to termites |
| Carpenter ant debris | Shredded fibrous wood mixed with insect parts, no uniform pellet shape | A carpenter ant nest, not termites |
If what you're finding matches that first row — small, uniform, oval, ridged pellets with no smell — you're looking at drywood termites. Our full field guide to identifying termite damage covers the other signs that tend to show up alongside frass.
Why It Keeps Coming Back
Drywood termites don't store waste inside their galleries — they push it out. Workers periodically clear frass through tiny "kick-out holes" (about the size of a pinhead) to keep their tunnels from filling up. That means a single active colony produces frass continuously, for as long as it stays active. Some colonies push out a little every day; others do it in less frequent batches. Either way, sweeping up what's on the sill doesn't touch the source — the kick-out hole is still there, and the colony behind it hasn't gone anywhere.
Frass is a symptom, not the problem. This is the same reason surface fixes don't work — like spraying swarmers with bug spray, which we covered in I sprayed termite swarmers with Raid: treating what you can see does nothing to the colony living inside the wood.
Where It's Coming From
Frass falls almost straight down from the hole that produced it, which makes the location of the pile a genuinely useful clue. Pellets on a windowsill usually mean the source is in the frame directly above. A pile along a baseboard means to look up the wall above that spot. The kick-out hole itself is easy to miss — pinhead-sized, often mistaken for an old nail hole. A flashlight held at a low angle across the surface will often catch the small shadow it throws.
What It Confirms — and What It Doesn't
Recurring frass confirms one thing clearly: there's an active drywood colony near where you're finding it. What it doesn't tell you is how large the colony is, how long it's been established, or whether it's the only one — drywood colonies are often independent, so a home can have separate activity in a window frame, the attic, and the garage all at once. It also can't tell you what treatment is appropriate; that depends on how extensive and how accessible the activity is, which is what an inspection determines.
What to Do
Stop treating cleanup as the fix. If you can, leave the most recent pile in place before your inspection — the amount and pattern of frass helps the inspector, and a fresh sample makes species identification straightforward. If you need to clean it, snap a photo with a coin next to the pile for scale first.
From there, a free inspection identifies the species, locates the colony (or colonies), and gives you a written report with treatment options matched to what's actually found. Frass is one of several signs worth checking for together — our 5 warning signs of a termite infestation covers the rest.