Virtually all insects require moist living conditions in order to survive, and exposure to dry conditions causes insects to dessicate and die. Insects breathe by sucking oxygen into their body through little holes on their abdomen called “spiracles.” From there, oxygen is delivered straight to an insect’s tissues through tracheal tubes. This primitive form of respiration allows water to rapidly escape through spiracles and through the thin cuticle coating an insect’s body. Subterranean termites have a relatively thin cuticle, which makes them particularly vulnerable to dry conditions. In fact, subterranean termites must remain within moist soil at all times, as exposure to the outside air, even moist air, will cause the insects to dessicate in less than a minute.
Workers from subterranean termite colonies readily infest structural wood that comes in contact with the moist ground soil. This is why modern residential building codes require all structural wood within a home to be elevated several inches above the ground. However, workers can still access above ground structural wood by constructing air tight mud tubes out of a hardening mixture of soil, saliva, feces and bits of wood matter. These mud tubes are constructed progressively upwards from the ground until they make contact with substructural wood around foundations.
Mud tubes allow workers to travel back to the soil to hydrate as needed, but their reliance on moisture limits their infestations to moist wood sources. Mud tubes are often visible on the exterior foundation walls of infested homes, but they are also commonly found on interior foundation walls, or they may be hidden behind stucco or another type of decorative exterior coating. Drywood termites have a much thicker cuticle than subterranean termites, which makes drywood termites more resistant to dessication. Because of their thicker cuticle, drywood termites are able to infest new sources of dry lumber.
Have you ever found subterranean termite mud tubes attached to your home?