Colony size, foraging activity, foraging phenology, and selected physiological parameters were evaluated on colonies of the western subterranean termite,Reticulitermes hesperusBanks, in urban and undisturbed habitats. The greatest foraging activity occurred from May to October at the University of California, Riverside urban site, and from late November to January at the Motte–Rimrock natural study site. Foraging activity was related to minimum temperatures at the urban site, and minimum temperatures and precipitation at the undisturbed site. Foraging population was greater in the urban habitat, with estimates ranging from 85,752 to 830,581 foragers compared with 78,930 to 103,758 at the native site. Termites at the urban site had greater initial and dry body weights, but less body fat than their counterparts from undisturbed habitats. No difference in the cuticular permeabilities of termites occurred between locations.