The entomopathogenic fungus Paecilomyces fumosoroseus and certain related species, such as P. javanicus are useful for controlling infestations by subterranean termites, particularly those belonging to the family Rhinotermitidae. The family Rhinotermitidae includes two species of subterranean termites having extremely high economic importance in the United States; namely the Formosan subterranean termite (Coptotermes formosanus Shiraki), and the native (North American) subterranean termite (Reticulitermes flavipes). Large numbers of infectious propagules of the fungus, such as blastospores and conidia can be readily cultured on media that are easily and inexpensively prepared and incorporated into formulations for controlling termites. These fungi are useful for protecting living trees, plants, wood, wood structures, and other cellulosic materials susceptible to termite infestation and damage.