Schedorhinotermes: two soldier castes, and why that matters
The second genus on every Australian inspector's list. It is quieter than Coptotermes, and it arrives from underneath.
What is Schedorhinotermes?
Schedorhinotermes is one of the small group of Australian termite genera that attack buildings. It is generally placed second only to Coptotermes for the amount of structural damage it causes in this country. Its field hallmark is unusual and easy to state: its soldiers come in two distinct sizes within the same colony, a large major soldier and a much smaller minor soldier. No other common Australian structural genus does that.
The species an inspector is most likely to name on the east coast is Schedorhinotermes intermedius; there are others through the north and the south-east. Which species it is will not change what you should do this afternoon, which is nothing at all. Which genus it is does change the plan, and that is why the page exists.
Why two soldier castes matter
In most termite genera the soldier caste has one form. Here there are two. The major soldier has a large, heavily built head with long curved mandibles. The minor soldier is markedly smaller, with a narrower head and finer mandibles, and to an untrained eye it can look like a different insect altogether. People who scoop up a sample regularly assume they have collected two species.
That matters for a practical reason. Soldiers are the caste that carries the features used to tell genera apart; workers of all the structural genera look much the same as each other. So a sample that happens to contain both soldier forms is genuinely useful to whoever identifies it. And a sample you have sorted and thrown half of away is less so.
We will not identify your specimen from a photograph or a description. And neither should anyone else. Someone who does it for a living makes the determination, on soldiers under magnification. And getting the genus wrong changes which approach makes sense. What you can do is collect a few insects, including any of the bigger-headed ones, into a sealed container. Write down the date and the exact spot they came from, and hand the lot to the inspector.
Where it nests, and how it reaches the house
This genus nests in and around timber in contact with the ground: stumps, the root crowns of living and dead trees, buried offcuts and old sleepers, fence posts. And debris and fill left under a building. It also nests in the subfloor itself.
A Coptotermes colony keeps one tightly defined central nest. A Schedorhinotermes colony tends to be spread through a main nest and a set of subsidiary workings. That is part of why the thing you find is so rarely the thing that matters.
The route into a house follows from that. It starts with ground contact (a stump, a post, a pile of formwork timber nobody removed when the place was built). Then it moves into bearers and joists from underneath, and upward into wall framing. A subfloor that is damp, poorly ventilated and used to store timber is the setting this genus is best suited to. Moisture, subfloors and ventilation covers the conditions side of that in detail.
How it compares with the genera you will hear named alongside it
| Genus | Soldier caste | Usual nest | Where the damage tends to show |
|---|---|---|---|
| Schedorhinotermes | Two sizes: major and minor soldiers in the one colony | Stumps, ground-contact timber, fill and debris under the building | From the subfloor upward. Bearers, joists, then framing |
| Coptotermes | One form, with a white secretion from a pore on the forehead | One concealed central nest: tree, stump, under a slab, wall base | Anywhere in the structure; long foraging runs to get there |
| Nasutitermes | One form, with a nozzle instead of mandibles | Visible carton nests on trunks, or domed mounds | Weathered and decaying timber: fences, decking, retaining walls |
| Mastotermes | One form; northern Australia only | Very large colonies, northern range | Unusually broad, and severe within that range |
Why it tends to be found late
Not because it is rare, but because of where it works. This genus is at home in concealed, ground-contact positions (under the floor, inside a post, within the fill). It does not run a long obvious mud tube up the exposed face of a pier where a householder would walk past it.
So the first real evidence is often found by somebody who deliberately goes under the house with a torch and looks. That is exactly what a timber pest inspection to AS 4349.3 involves, and what a walk around the living room does not.
It is also the reason the subfloor is worth keeping accessible. An inspector who cannot get under a section of the house cannot report on it. And the part nobody can reach is a reasonable guess at the part that has been undisturbed longest.
What to do if you think this is what you have found
Leave it alone. Do not break open the workings to see what is inside. Do not lift the damaged board to find out how far it runs. Do not spray it with anything, and that includes the products sold for ants and general insects at the supermarket.
The reason is mechanical rather than moral. Disturbing or spraying active workings makes the colony seal off that route and abandon it: and then re-enter the building somewhere else, out of sight. The feeding continues; you have simply lost track of where.
You will also have destroyed the evidence trail the inspector was going to read. If a colony-directed treatment is later used, you will have damaged the very thing it depends on: workers moving freely along a known route and sharing what they carry.
Photograph it, leave it exactly as it is, and book an inspection. Every termiticide and bait active used in Australia is registered by the APVMA and applied by a licensed pest management technician. Nothing here is a recommendation to buy or apply any product. If you want a sense of what an inspector looks at before you call one, the fifteen-minute walk-around is the touch-nothing version.
Frequently asked questions
How do I know if my termites are Schedorhinotermes?
You do not, and nobody can tell you from a photo. The determination is made on soldiers under magnification. What helps is the sample: if the insects you collected include both a large heavy-headed form and a much smaller one, that combination is meaningful to the person identifying them. Collect a few in a sealed container, note the date and the exact spot, and hand them over.
Is Schedorhinotermes as destructive as Coptotermes?
It is generally placed second, which is not the same as harmless. It attacks structural timber and it is capable of serious damage. The practical difference is where it comes from and how it behaves: ground-contact timber and the subfloor rather than a single concealed central nest with very long foraging runs.
Why do the soldiers look like two different insects?
Because the caste is dimorphic. The colony produces both a major soldier with a large, heavily built head and long mandibles, and a minor soldier that is much smaller and finer. Both are the same species, and the combination is one of the things an identification looks for.
Can I treat it myself if the nest is only in a stump in the yard?
No. Termiticides and bait actives are registered by the APVMA and applied by licensed pest management technicians, and beyond the licensing there is a practical problem: this genus works through a main nest plus subsidiary workings, so the stump you can see is not reliably the whole colony. Attacking it tends to scatter what you had located.
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
- Australian Pesticides and Veterinary Medicines Authority. Registered agvet chemical products (PubCRIS)
- Standards Australia. Australian Standards (AS 3660 termite management, AS 4349.3 timber pest inspection)