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Signs Termites Could Be Feasting on Your Home

Dini Miller, Ph.D., Virginia Tech

Homeowners rarely realize termites are causing damage to their house until the cellulose-hungry insects have permanently damaged the structure. This damage may be a surprise because termites are cryptobiotic, meaning their activities are hidden from view. Termites’ cryptobiotic behavior contributes to their success in invading human structures. Termites can consume the inside of a 2" x 4" piece of framing wood, but still keep the outside of the wood surface intact. Most homeowners have no idea that termites have infested their house unless they break through the surface of an infested piece of wood or they see other signs of termite damage, such as a swarm

While termite colonies are extremely difficult to see, there are several signs of termite infestations that every homeowner should know.

Subterranean Termites:

Subterranean termite mud tubeMud Tubes - Subterranean termites need moisture to survive, which means they rely on their soil habitat for the moisture they need. When termites travel above ground, they have to take the soil with them to protect themselves from drying out. Subterranean termites build mud tubes above ground so termite workers can travel inside the protected structure when foraging between the infested wood and their nest. The tubes may be easy to spot when they extend over concrete foundations and other exposed surfaces. However, the tubes are much less visible when they run along cracks in the foundation or behind siding and baseboards.

Wood Damage - Subterranean termites only like to eat soft spring wood fiber, which means they will eat along the wood grain, rather than across it. Subterranean termite damage is very easy to identify because the damaged wood will only have the grain left behind. Since subterranean termites carry soil with them, the spaces between the wood grains are typically packed with mud. Both drywood and subterranean galleries (small rooms inside the wood connected by tunnels) can be detected by tapping a piece of wood every few inches with the handle of a screwdriver. The damaged wood will sound hollow, and the screwdriver may even break through the wood into the galleries.


Drywood Termites:

Termite droppings (frass)Frass (Termite Droppings) - As drywood termites eat their way through wood, they produce frass or wood-colored droppings. For housekeeping purposes, sometimes the termites will chew small holes in the wood to push these droppings out. Termite fecal pellets can be found in little piles beneath the infested wood.

Wood Damage - Drywood termites eat right across the grain of the wood and leave very clean galleries; in fact, these galleries are so clean that they look like they have been smoothed with sand paper. Inside these galleries, you will find mounds of fecal pellets piled up where they have been pushed out of the way by the termites.

Both Subterranean and Drywood Termites:

Formosan termite swarmers (alates)Swarmers - Winged termite swarmers may emerge inside or outside your home. A swarm is often the first visible sign of a termite infestation. Because swarmers are attracted to light, they are often found around lighting fixtures in a home and in windowsills. Drywood termites produce relatively small swarms (10-100 swarmers), so if the homeowner is not home during the drywood swarm, the termites might go unnoticed. However, subterranean termites could produce hundreds to thousands of swarmers. An indoor swarm of such massive numbers is hard to miss.

Discarded Wings - Swarmers break off their wings shortly after they land on the ground. While the termites may quickly disappear, the groups of identical, disembodied wings discarded on windowsills, floors or in spider webs are sure signs of an indoor termite swarm.

Mounds - Many people have heard that termites build large mounds out of soil to house entire colonies of termites. While this practice is true for some termite species found in Australia or Africa, the United States has no mound-building species of termites. A mound of earth found in the yard of a home in the U.S. is most likely due to some sort of wildlife, not termite, activity.

Click here to find out whether your area is prone to activity from drywood termites, subterranean termites, Formosan termites or dampwood termites.