Studies have shown that subterranean termites will not forage in areas where upper level soil temperatures are either too hot or too cold. During the year, the center of colony activity may shift from outer to inner portion of a log or from the soil surface to areas deep underground due to temperature. The amount of moisture required by termites varies among species.
Subterranean termites are very vulnerable to dryness and require a constant supply of moisture.
In urban areas they may get this moisture from plumbing leaks, shower pan leakage and sprinkler irrigation. Too much water, however, can be lethal to subs. Soil is what subterranean termites go through to reach new sources of food and the material they use to build tunnels below and above ground. It is also the main supply of moisture. In clay soils moisture is bound to the soil and not as readily available to the termite.