Flying Termites (Kelkatu) After Rain
Is It an Infestation? An Honest Checklist (2026)

What kelkatu actually are

Kelkatu, also called laron in some places and 大水蚁 in Chinese, are winged termites. A mature colony produces them once or several times a year. Warm, wet weather triggers the flight: the winged adults leave the nest together, fly a short distance, drop to the ground, shed their wings, pair off and try to start a new colony in the soil. The University of Kentucky’s termite guide describes exactly this sequence, triggered by warmth and rainfall.

That is why the evening after a heavy rain can bring hundreds of them around a porch light, and why you wake up to a carpet of loose wings on the floor. The swarmers do not damage timber. The worker termites that stay behind in the colony do.

Inside or outside: the question that decides everything

The same university guide draws the line clearly. Winged termites discovered indoors almost always indicate an infestation that needs treatment. Swarms coming out of tree stumps or woodpiles in the yard are not necessarily cause for concern and do not automatically mean the house is infested. Swarmers coming out next to the foundation, or from an abutting porch or patio, mean there is a good chance the house is infested too.

Our termite control guide lists the swarm among the signs of an active colony. The inside-or-outside test above is how you tell whether that colony is in your house or next door.

Termite or flying ant?

Flying ants swarm at similar times and are often mistaken for termites. The university guide gives the three checks you can do with a phone camera and a torch:

• Antennae: straight on a termite, elbowed on an ant.
• Waist: uniformly thick on a termite, pinched and narrow on an ant.
• Wings: four wings of equal size on a termite; on an ant the front wings are longer than the back pair.

Termite wings also break off easily, which is why they are left in piles. Ants keep theirs longer.

What to do on the night of the swarm

1. Switch off lights near open windows and doors, and close them. Swarmers are attracted to light.
2. Sweep or vacuum the swarmers and wings. They cannot damage wood and do not live long without soil.
3. Before you clean up completely, note where the wings are thickest and look for the exit point: a crack, a gap under a skirting, a hole in a door frame.
4. Leave any mud tubes alone. An inspector needs to see them undisturbed.
5. Do not spray insecticide into the exit hole or seal it with silicone. That scatters the colony and hides it.

Why it always happens after rain

Swarming is timed to give the new pairs the best chance of survival. Warm air, still evenings and damp soil right after rain make it easier for a pair to dig in before they dry out. In Malaysia that means the monsoon months and any heavy late-afternoon storm. Seeing kelkatu at the same time as the rest of the street is normal; seeing them come out of your own walls is the warning.

Other signs to check the next morning

• Mud tubes, about pencil width, running up a wall, pillar or door frame.
• Skirting or door frames that sound hollow when tapped, or give under a thumbnail.
• Paint that bubbles or ripples on timber or plaster near the floor.
• Doors or windows that have started to stick.
• Fine sawdust-like pellets near furniture, which points to drywood termites instead; see our drywood termite and bubuk guide.

What an inspection will look for

A proper inspection goes round the whole house, not just the room with the wings: the perimeter, wet areas, built-in carpentry, door frames, the roof space where it is accessible, and the conditions that feed a colony, such as leaks and timber in contact with soil. The report should say whether activity is live, where it is and why it is there. Our termite inspection guide explains what the written report must contain.

What treatment typically costs

If the inspection confirms a colony, the two common routes are a soil treatment or a baiting system. Our termite inspection guide publishes these indicative 2026 Klang Valley ranges:

Which route suits depends on the building, the species and how the colony is getting in; our termite baiting guide compares the two.

Making the house less inviting

• Fix leaks and damp areas; termites need moisture.
• Keep firewood, old timber and cardboard off the ground and away from the walls.
• Stop soil or planter boxes from touching timber frames and skirting.
• Keep the gap under raised timber floors and decks open and dry.
• After a swarm season, walk the perimeter and look for new mud tubes.

How ClickBina can help

Termite damage often turns up during renovation, behind a wardrobe or under a kitchen cabinet, and the carpentry and frames then need repair after the colony is dealt with. ClickBina is an experienced KL & Selangor contractor that handles whole-house refurbishment and coordinates the trades on one job. WhatsApp us your job details for a quote: where the swarmers came from, which rooms, and whether you have seen mud tubes or hollow timber. We reply within the hour, the price we agree is a flat price with no hidden charges, and a site visit is RM150, waived if you go ahead.

Sources & methodology

• University of Kentucky Entomology, Termite Control Options (ef604) — swarming trigger, indoor versus yard swarms, attraction to light, termite versus ant identification.
• UC IPM Pest Notes: Drywood Termites — swarmers as the most common sighting, and why confirming an infestation needs an inspection.
• ClickBina termite inspection guide — the indicative treatment prices quoted above.

How we estimated prices: every RM figure is quoted unchanged from the ClickBina guide named above; they are typical Klang Valley ranges for 2026, not fixed rates.