Carpenter ants vs termites: how to tell the damage apart
Both can leave a wall full of tunnels. Only one of them is eating your house.
The short answer: one eats wood, one only tunnels in it
Termites eat timber because the cellulose in it is their food. Carpenter ants excavate timber to make room for a nest, and they feed on other things. That difference explains almost every other difference between the two kinds of damage.
It also means the stakes are different. A carpenter ant nest in a damp, softened beam is a warning about moisture. A termite colony in the same beam is a threat to the structure. Do not guess which you have.
What the damage looks like
| Clue | Carpenter ants | Termites |
|---|---|---|
| Inside the galleries | Smooth and clean, almost sanded | Rough, often with mud, soil or dried droppings packed in |
| Debris | Sawdust-like shavings pushed out of small holes, sometimes with bits of dead insects | Little visible debris. Pellets (frass) in some groups, mud lining in others |
| Tubes on surfaces | None | Mud tubes across masonry, slabs and stumps in many species |
| Insects you see | Ants moving in and out, usually at night | Pale workers when timber is opened. Winged forms after rain |
| Sound | A faint rustle in a quiet room | A hollow, papery note when you tap the timber |
Treat the table as a guide to what to tell the inspector, not as a diagnosis. Damage can be old, mixed, or both.
Why a hollow beam is not proof of termites
Hollow timber is the same worry in both cases, so people jump to the worse answer. Sometimes that is right. Sometimes it is a carpenter ant colony working in wood that was already wet, or a borer problem, or old rot.
The reverse mistake is more costly. Cleaner-looking galleries do not rule termites out, because some groups keep their workings tidy. Only a licensed timber pest inspector can say which one it is.
Do not poke, spray or open it up
With ants, spraying can scatter the colony into new spots in the walls. With termites, it is worse: disturbing the colony makes it abandon that run and come back later through a path you cannot see. It also destroys the evidence the inspector reads.
So the rule is the same for both. Leave the timber as it is. Note where you found it, photograph it from a short distance. And keep a few insects in a sealed container if you can collect them without opening the wood.
What to do next
Book a licensed timber pest inspection and say what you saw: smooth or rough galleries, any mud, any debris, and when the insects appear. Treatment of either pest is work for a licensed technician using products registered by the APVMA. If the answer is ants, expect the inspector to ask why the timber was damp enough to attract them.
For the quick insect check, see termite or ant: waist, antennae, wings. Do not touch the timber until the inspector has seen it.
Frequently asked questions
Do carpenter ants eat wood?
No. They cut tunnels in timber to nest in it, and they feed on other foods. Termites are the ones that eat the wood.
Can I tell carpenter ant damage from termite damage myself?
Smooth, clean galleries with sawdust-like shavings point to ants, and rough galleries with mud or droppings point to termites. It is only a guide, so have a licensed inspector confirm it.
Should I spray the nest if I think it is carpenter ants?
Leave it for the inspector. If it turns out to be termites, spraying can push the colony to hidden spots and destroys the evidence.
Does a carpenter ant nest mean my timber is damp?
Often it does, because they favour softened wood. That is a reason to look for the moisture source as well as the insects.
Sources
What this page explains is based on these official sources. If you check one and it does not match what you read here, send it to us and the article gets corrected.
- Department of Health, Victoria. Pest control: termites
- Queensland Building and Construction Commission. Protect against termites: termite management systems and inspections
- Standards Australia. Australian Standards (AS 3660 termite management, AS 4349.3 timber pest inspection)
- Australian Building Codes Board. National Construction Code