Why do termites target wooden structures?

Termites can't digest cellulose on their own — no animal can, without help. Eastern subterranean termites belong to a 'lower' termite lineage that carries flagellate protozoa in the hindgut, and those protozoa secrete the cellulase and cellobiase enzymes that actually break wood cellulose down into digestible sugars. Britannica states plainly that without these symbionts, termites would starve. That single biological fact explains the entire behavior: a termite colony isn't choosing to eat wood out of many options — cellulose is nearly the only food source its digestive system is built to use, and wood is concentrated cellulose.

Foraging workers leave the underground colony through mud tubes and search outward for any accessible cellulose, moving essentially at random relative to what's above ground — a fallen log, a wood pile, a fence post, or a home's sill plate are functionally the same to a foraging termite. There's no scouting behavior aimed at houses specifically, no preference for a particular building, and no intent behind which structure gets found. What determines whether a home is affected is simply whether it offers the conditions a colony needs to reach it: wood in or near soil contact, combined with enough moisture to sustain feeding.

Because the mechanism is a search for cellulose near soil moisture, that combination is also the honest boundary of the risk. Sill plates, floor joists, subflooring, and any wood in ground contact are genuinely exposed. Concrete, masonry, and steel are not — termites will tunnel around these materials but cannot eat or digest them under any circumstance. And wood that has no soil contact and stays dry is largely outside a colony's practical reach, which is exactly why moisture control and wood-to-soil separation are the two most effective preventive measures a homeowner can take.

Only one termite species, the eastern subterranean termite, is established in New Hampshire; the state sits in a moderate pressure zone by industry classification, and drywood and Formosan termites — species responsible for some of the more dramatic damage figures circulating nationally — are not present here at all. New Hampshire's cold winters also slow termite feeding activity for several months each year, which is one more reason the honest structural timeline in this state runs in years rather than the fast-moving picture sometimes implied by national marketing.