You switch on the passage light one evening after a spell of rain and within minutes there's a small cloud of flying termites circling it. By morning, there's a carpet of discarded wings on the windowsill or floor below — and that's usually the last anyone thinks about it, because the swarm itself is gone in a day. That's a mistake. The swarm point isn't random, and in most Bangalore homes we've inspected, it marks exactly where a colony has been quietly feeding on damp wood for months.
Why the swarm happens right after rain
Winged reproductive termites — alates — leave a mature colony specifically when humidity is high enough for them to survive outside the nest long enough to pair off and start new colonies elsewhere. A Bangalore evening after a good shower is exactly that window, which is why swarms cluster so reliably in the day or two after rain, drawn straight to tube lights and window glass. The swarm you see is the colony announcing it's mature and well established — not the start of a problem, but a sign one has already taken hold.
The swarm point is a clue, not a coincidence
Where the wings pile up usually sits directly at or near the colony's food source. In Bangalore homes, that's almost always one of three spots:
- A wooden door or window frame embedded in a wall that's stayed damp from ongoing seepage — the frame absorbs moisture from the wall behind it and stays soft enough for termites to tunnel through undetected.
- False ceiling battens or plywood near a slow terrace or AC condensate drain leak — moisture tracks along the batten and sits there far longer than anyone realizes, since it's hidden above the ceiling board.
- Skirting boards or almirah legs on a floor with rising dampness, usually because the slab was laid without a proper damp-proof course — the wood wicks moisture straight from the floor.
All three give termites exactly what they need: cellulose to feed on and consistent moisture to survive, hidden inside a wall or floor cavity where nobody's looking.
The check to do this week
- Sweep up the discarded wings and note the exact spot — that's your starting point, not just wherever you noticed the swarm from your sofa.
- Press a screwdriver or key gently into any wood at that spot — a hollow sound or crumbly surface means active termite damage.
- Look for pencil-thin mud tubes running up the wall, frame or furniture leg near the swarm point — this confirms an active colony, not just a one-off flight of flying ants.
- Check the wall or floor right behind or below that spot for dampness, discoloration or a musty smell — this is the moisture source feeding the colony.
- Check other rooms too, not just the one you saw the swarm in — termites travel through wall and floor voids, so the colony is often bigger than the visible swarm suggests.
Mud tubes mean the colony has been established for a while, not days. Spraying the visible swarmers does nothing to the underground or in-wall nest, and treating the pest problem without finding the moisture behind it usually means new activity within a season — the wood stays damp, and termites (or plain wood rot) come right back.
Pest treatment fixes the termites, not the reason they came in
A proper termite treatment — a chemical soil barrier or a baiting system around the affected area — is the right call for the colony itself, and that's a licensed pest control job, not ours. But if the frame, batten or skirting board stayed damp because of unresolved wall seepage, a slow terrace leak or rising floor dampness, that moisture problem doesn't go away just because the termites did. Get the leak or seepage diagnosed and sealed alongside the pest treatment, or you're paying for the same fix twice within a year.
We check for the leak or seepage source behind damp wood, skirting boards and false ceilings as part of any home inspection — and we'll point you to pest control separately if the colony itself needs treating. Call +91-8123083393 for a free on-site check, this week.
Frequently asked questions
Winged reproductive termites (alates) leave a mature colony to start new ones when humidity is high enough to survive outside the nest, which is exactly the window a rain shower followed by a warm evening creates. That's why swarms almost always show up a day or two after rain, drawn to tube lights and windows in the evening.
Not necessarily, but it means a colony is established somewhere nearby, usually in a damp wooden frame, false ceiling batten or skirting board. The swarm itself doesn't cause damage, but the colony it came from has likely been feeding on wood in that spot for a while.
No. The winged termites you see and spray are a small fraction of the colony leaving to start new nests elsewhere. The main colony stays hidden in the wall or floor cavity and needs a proper chemical barrier or baiting treatment, not a can of spray on the swarmers.
Pest treatment kills the colony, but if the wood near that spot is still damp from an unresolved wall seepage, a slow terrace leak or rising dampness through the floor, new termite activity or wood rot tends to return within a season. The moisture source has to be fixed too, not just the pest problem.