Nasutitermes: nozzle-headed soldiers and nests in plain sight
Most termite genera are found by evidence. This one you find by looking at a tree: which is exactly why it is so often misread.
The soldier with a nozzle instead of jaws
Nasutitermes is the easiest Australian termite genus to recognise, because its soldiers gave up the usual weapon. Instead of the large biting mandibles a Coptotermes soldier carries, a Nasutitermes soldier has a dark, pointed, pear-shaped head drawn out into a snout (the nasus). From it, the soldier squirts a sticky, resinous defensive fluid at whatever is bothering it. The genus is simply named after that snout.
In practice, say a nest or a gallery gets broken open. If the defenders swarming out have small dark pointed heads, not pale bodies with obvious jaws, you are almost certainly looking at this genus. It is the one case where the field mark is visible without magnification. It is still not a determination you should be making, for reasons further down. But the mark is real, and people see it. That is why the genus turns up so often in conversations about termites.
The nests: carton in a tree, a dome in the paddock
This is the genus responsible for most of the termite nests Australians actually notice. Several species build nests you can see and touch:
- Arboreal carton nests. Dark brown, rounded, roughly football-sized or larger lumps stuck to the trunk or a fork of a tree, sometimes on a fence post or a power pole. The material is carton: chewed timber and faeces worked into a brittle papery mass. In eastern Australia these are commonly Nasutitermes walkeri. Covered runways typically lead down the trunk to the ground.
- Low domed mounds: earthy, hard, usually well under a metre high, in paddocks, bushland and the back corners of larger blocks through southern Australia. Nasutitermes exitiosus is the usual builder.
- Cathedral mounds: the tall, fluted, sculptural mounds of the Top End belong to a Nasutitermes species too. Those colonies feed on grass and dead timber in the bush and are not a house problem; they are simply the most photographed termites in the country.
What a visible nest tells you — and what it does not
| What you can see | Usually means | What it tells you about the house |
|---|---|---|
| Dark, brittle, rounded nest on a tree trunk | Arboreal Nasutitermes | Lower structural risk, but a live colony on the property. It says nothing about what else is there |
| Low earthy dome in the yard or paddock | Mound-building Nasutitermes | Same: a known colony close by, worth an inspection, not a reason to panic |
| Tall fluted mound, northern Australia | Grass-feeding bush species | Effectively nothing: these are not building pests |
| No visible nest anywhere | Nothing at all | The genera that damage houses most nest out of sight. Absence of a nest is not absence of termites |
That last row is the important one. The genus behind the bulk of Australian structural damage, Coptotermes, nests centrally and out of sight: inside a living tree, a stump, under a slab, in the base of a wall. There is nothing on the surface to find. A tidy yard with no mounds in it is not evidence of anything. The visible nest is the exception, not the measure.
What it eats, and why the risk is lower but not zero
Nasutitermes generally prefers timber that is already weathered, damp or partly decayed. In practice that means fences, posts, retaining walls, sleepers, decking, stored timber and stumps take the damage, rather than dry structural framing. That is a real difference from Coptotermes, which attacks sound, seasoned timber readily.
"Lower risk" is not "no risk", and N. exitiosus in particular does attack buildings. Where it gets into a house, it typically uses the same routes anything else does (ground contact, subfloor timbers, a bridged barrier). And it finds the damp, poorly ventilated parts first. Moisture, subfloors and ventilation covers why those areas are where the trouble starts.
Why the snout still does not let you make the call
The nasus is a genuine, visible field mark, and that is precisely what makes it a trap. It tells you what is in the nest you opened. It tells you nothing about what is in the wall cavity, under the slab or in the subfloor. More than one colony of more than one genus on a single property is entirely ordinary. Deciding that the property's termites are the low-risk kind because there is an obvious nest in the gum tree is the mistake this page exists to head off.
Beyond that, we do not identify termites from photographs or descriptions, and neither should anyone else. Species within the genus are separated on soldiers under magnification. An inspection to AS 4349.3 answers the practical questions: which colonies are on the property, which one is feeding on the building, and where it is nesting. A picture of a nest does not.
What not to do with a nest you have found
The urge to deal with a nest you can actually reach is strong, and it is the wrong instinct in every direction:
- Do not knock it down, poke it or open it up. Breaking a carton nest scatters a colony that was, until that moment, in a known location. It may relocate, and it will not necessarily relocate somewhere better for you.
- Do not spray it or burn it. Beyond the obvious hazards, an aerosol reaches the outside of a nest and not the queen inside it, and destroying one colony in a tree does nothing whatsoever about a different colony feeding on the house.
- Do not remove the runways up the trunk. They are part of what an inspector reads to work out how far the colony is foraging and in which direction.
Every termiticide and bait active used in Australia is registered by the APVMA and applied by a licensed pest management technician. They make the call on whether a nest on the property should be treated at all, with the whole property in view. Sometimes a known, monitored nest is more useful than a destroyed one.
What to do instead
Photograph the nest where it is, note how far it is from the building and whether any runways lead towards the house, and leave it alone. Then get the building inspected, because the nest you found is information about the property, not a verdict on the house.
If you want to look over the rest of the place first without touching anything, the fifteen-minute walk-around is the touch-nothing version. And mud tubes explains the covered runways you may find on a pier, a wall or that same tree trunk.
Frequently asked questions
There is a termite nest in a tree in my yard. Is my house at risk?
It means there is a live colony on the property, which is a reason to have the building inspected, not a reason to panic. Arboreal carton nests usually belong to Nasutitermes, which favours weathered and decaying timber over sound structural framing. The more important point is the reverse one: having found this nest tells you nothing about whether a concealed colony of another genus is also present.
Should I get rid of the nest?
Not yourself, and not by knocking it down. Breaking a nest open scatters a colony whose location you currently know, and spraying the outside does not reach the queen inside. Whether a nest on the property is treated, monitored or left is a judgement a licensed technician makes with the whole property in view, and a known nest is sometimes more useful than a destroyed one.
How do I tell Nasutitermes from other termites?
The soldiers are distinctive: a dark, pointed, pear-shaped head drawn into a snout, with no large biting jaws. It is the one Australian genus with a field mark you can see unaided. Even so, species-level identification is done on soldiers under magnification, and what matters for your house is which colonies are where. An inspection question, not a photograph question.
Are the big mounds in northern Australia dangerous to houses?
The tall fluted cathedral mounds of the Top End are built by a grass-feeding species that lives on grass and dead timber in the bush. They are not a building pest and the mounds themselves are not a warning about your house. The termites that damage Australian houses mostly build nothing you can see.
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)