Subterranean termites, and why the soil matters
The termites that damage buildings here live in the soil and come up into the structure for cellulose: door frames, skirtings, wardrobe backs, stored paper and anything timber touching or near the ground. They travel inside mud tubes they build themselves, because they dry out in open air, and those tubes running up a wall or a foundation are usually the first visible sign.
That biology decides the treatment. Killing the insects you can see achieves nothing, because the colony is in the soil and will send more. What works is treating the soil so the route between colony and building stops being usable, which is why termite work is drilling and injection rather than spraying a skirting board.

