The foraging territory size ofHeterotermes aureus(Snyder) was investigated on the Santa Rita Experimental Range south of Tucson, Ariz. A comparison of three techniques for delineating territorial boundaries suggested that the release and recapture of dyed termites and agonistic behavior among termites were the most reliable techniques, whereas spatial and temporal patterns of termite attack on baits were unreliable for determining boundaries. Data obtained with the first two techniques indicated that many territories encompassed an area of several hundred to a few thousand square meters. These data contrasted sharply with those obtained from spatial and temporal patterns of termite attack, which provided an estimate of 13.9 m2for average territory size.