Subterranean termite colonies are usually located between two and 20 feet below the ground. The primary nest that houses the king, the queen, and her eggs (alates) is always situated in moist areas of soil, and workers move along moisture gradients in soil while foraging. Subterranean termites are highly dependent on soil-moisture for their survival, as exposure to dry soil will cause subterranean termites to dessicate and die. Exposure to the outside air is out of the question for subterranean termites, as the air humans breathe will cause subterranean termites to rapidly dry up and die.
Workers seek out moist wood that is either located below the ground or in contact with the ground, but after infesting wood, workers must periodically return to the ground soil to hydrate as needed. In rare cases, workers infest wood that is moist enough to provide them with all the water they need, making return trips to their usual soil habitat unnecessary. In very rare cases, swarming subterranean termites (alates) initiate new colonies within damp structural wood, but the vast majority of subterranean termite colonies are initiated with moist soil. In order to access above-ground wood without dying from air exposure, workers construct air-tight “mud tubes” that connect the ground soil with above-ground structural wood.
Mud tubes are made from a mixture of soil, bits of wood, saliva, and fecal material. Saliva and fecal material serve as hardening agents that cement mud tubes into place. Workers build four types of mud tubes, and “utility,” or “working tubes” are typically located on exterior and/or interior walls of foundations, and they are the most commonly sighted mud tubes by homeowners. Utility tubes provide a direct connection between the soil and above ground wood, and they allow workers to return to the soil to hydrate as needed. “Exploratory tubes” are similar to utility tubes, only they do not make contact with above ground wood. Workers build exploratory tubes in order to find above-ground wood sources that are sufficiently moist and provide ideal food for the colony. “Suspended drop tubes” are like reverse utility tubes in that they lead from above ground wood to the ground, instead of the other way around. “Swarming tubes” are built to provide alates with an exit from the colony nest site, and they are usually between 4 and 8 inches long, and they may make contact with above-ground wood. Swarming tubes are usually found below a furnace or in other warm areas within crawl spaces.
Have you ever found any type of subterranean termite tube in your crawl space?