Subterranean termites are the most economically significant pests of homes and buildings, as they inflict more than one billion dollars in property damage each year in the United States alone. Several subterranean termite species damage structural wood in the US, but the eastern subterranean termite is the most common and destructive species in the country. This is the only termite species found in Massachusetts, and their colonies are densely located beneath both urban and suburban areas throughout the state. Unlike drywood and dampwood termite species, subterranean termites dwell below the ground surface where workers seek out food sources away from their colonies. Subterranean termites are highly dependent on moist conditions in order to survive, and they generally limit their infestations to moist structural wood sources. Unfortunately, subterranean termites gravitate toward moist conditions within crawl space foundations where workers construct protective “mud tubes” in order to establish direct access to structural wood from their soil habitat.
Like any enclosed area above the moist ground soil, moisture content within crawl space foundations is relatively high, especially when air flow is hindered by vegetation blocking crawl space openings. Also, central heating keeps the soil beneath and around houses warm during the winter season, which allows subterranean termites to remain active within crawl spaces all year round. Subterranean termite workers are well known for constructing vertical mud tubes on exterior foundation walls in order to access above ground structural wood within homes. These mud tubes are conspicuous and indicate that a subterranean termite infestation has become established. However, the high moisture beneath homes can cause important structural wood components within crawl spaces to become saturated with moisture, making these wood sources particularly appetizing to subterraenan termites. This is why mud tubes are often located only within crawl spaces where homeowners cannot readily see them.
In crawl spaces, subterranean termites have no problem accessing structural wood sources like support posts, girders, joists, beams and piers that are located relatively close to the ground soil. In addition to warmth and humidity, the abundance of underground wood scraps leftover from a home’s construction also serve to attract subterranean termites to crawl spaces. Studies have shown that subterranean termites favor wood sources that are located near wet pipes and furnaces within crawl spaces, but vinyl coverings can trap moisture, preventing structural wood in crawl spaces from becoming damp. While reducing vegetation around foundation walls will help to reduce moisture within crawl spaces, a dehumidifier often remains necessary to keep the relative humidity level at or below 55 percent during humid Massachusetts summers. A relative humidity level of 55 percent or lower should be maintained in crawl spaces throughout the year to minimize the chances of a subterranean termite infestation.
Have you ever inspected your own crawl space for subterranean termite damage or infestation signs?