In nature, subterranean termites are beneficial. They break down many dead trees and other wood materials that would otherwise accumulate. The biomass of this breakdown process is recycled to the soil as humus. Subterranean termites derive their nutrition from wood and other material containing cellulose. Subterranean termites cannot digest cellulose directly. They depend on large numbers of one-celled animals (protists) living in the termite hind gut to break down the cellulose to simple acetic acid, which termites can digest. Worker termites and older nymphs consume wood and share their nourishment with the developing young, other workers, soldiers and reproductives.
Dead trees and brush are the original food source of subterranean termites.
These were "wild", living and feeding on fallen trees.