Winged insects swarming inside the house

What a swarm indoors tells you

The colony is close and it is mature. A colony only produces swarmers once it is several years old. When they come out inside, the insects found a way up from the soil into the walls — through a plumbing penetration in the slab, an expansion joint, or the gap behind brick veneer.

It often happens on a warm day after rain. Eastern subterranean termites, the main native termite in Texas, swarm in daylight. Texas A&M AgriLife puts the start in January and February in South Texas and April or May in the Panhandle; North Texas falls between, so March and April swarms are typical here. Most people first notice them near a window, a sliding door or a bathroom, because that is where light or plumbing is.

A swarm outdoors means less. Swarmers coming out of a fence post, a stump or a woodpile in the yard show that termites are in the neighborhood, which in North Texas is a given: AgriLife estimates that an unprotected home has about a 70 percent chance of some termite damage within 25 years. Indoors is the signal.

What the visit involves

A technician looks for where the swarm came from: the room it appeared in, the bath trap opening under the tub, baseboards along exterior walls, the garage slab joint and the outside of the foundation, where mud tubes often run up behind the brick line.

From that comes a treatment plan — a soil treatment around the foundation, a bait system, or both — and an explanation of how it is monitored afterward.

Tell the operator

• The date and time of the swarm and the room
• Whether you kept any swarmers or wings
• Whether you have seen mud lines on the foundation or garage wall
• The age of the house and whether a builder's termite warranty is still active