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Why spraying termites yourself makes it worse

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This is the one piece of advice on this site that matters more than the rest. If you find termites, do not touch them.

The instinct is completely reasonable

You lift a piece of bark, or break open a skirting board, and there are hundreds of pale insects. There is a can of surface spray under the sink. Everything about the situation says use it.

It is the wrong move, and the reason is not that it fails to kill them. It kills them. The problem is what the rest of the colony does next.

What actually happens

A termite colony reacts to a breach in its workings (a broken mud tube, an opened gallery, a sudden loss of workers in one area) as a threat to be sealed off. The response is to abandon that route and re-establish access somewhere else. In a house, somewhere else means inside a wall cavity, under the floor, behind cladding: places with no line of sight and no reason for you to look.

So the sequence is: you had a termite problem with a visible marker on it. You sprayed the marker. Now you have the same termite problem with no marker, and you have been given the impression it was dealt with. The damage continues for months or years, out of sight, and is found later and larger.

The second cost: you break the treatment

Modern termite control leans on the termites themselves. Non-repellent soil products and baits both work by being carried back: workers pick up a slow-acting product, return to the colony. And pass it on through grooming and feeding. That transfer is the mechanism.

A fast-acting surface spray does the opposite. It kills the foragers on the spot and it is repellent, so the survivors avoid the area. You have removed the couriers and taught the colony to stay away from the one place a technician could have reached it. The strategy that would have eliminated the colony is now much harder to run.

The third cost: the evidence

An inspector reads live evidence (damp workings, active galleries, the species of the soldiers) to work out what you have, how big it is and where the nest is likely to be. Sprayed, crushed and scattered evidence answers none of those questions. Identification is made from soldiers under magnification, and the genus changes the treatment.

What to do instead

  1. Stop. Put the lid back, step away, do not probe further.
  2. Photograph it from a distance, and note exactly where it is.
  3. Protect it from accidental disturbance if it is somewhere it might get knocked: put something in front of it rather than moving it.
  4. Book a timber pest inspection. Say on the phone that you have found live activity and have not disturbed it; that changes how quickly you get seen.
  5. Do not start repairs. Replacing eaten timber before the colony is dealt with feeds them in the same spot.

The one exception, which is not really an exception

If a piece of timber has to be moved for safety reasons, move it. Nothing here is worth an injury. But do it knowing you have probably relocated the problem, and tell the inspector exactly what you moved and when.

Everything else (including the strong urge to find out how bad it is) waits. The damage is nearly always worse than the surface suggests, and finding that out yourself costs you the only advantage you had.

Frequently asked questions

I already sprayed them. What now?

Tell the inspector exactly what you used, where, and when: do not leave it out. It changes what they can interpret from the site and may change the treatment strategy. It is a setback, not a disaster.

What about the ones I can see right now, are they going to spread while I wait?

A colony that has reached your timber is already established and already foraging. The days between finding it and an inspection are not what determines the outcome; what you do to the workings in those days can be.

Is it different if they are in a fence or a stump, not the house?

The advice is the same. A colony in a stump or a fence post is a colony with a food source next to your building, and it is exactly the situation an inspector wants to see intact.

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.

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