Nasutitermes octopilis Banks is an abundant termite in the Kartabo area and other forested regions of Guyana. It lives in moist dead wood, with a gallery development similar to that seen in some species of Rhinotermitidae. It does not build covered runways; instead, it tunnels in soil and forest floor litter.N. octopilis soldiers can withstand ant attack more effectively than soldiers of other commonNasutitermes species in the erea. Their secretion appears to be repellent to ants, and renders worker termites selected from groups of workers and soldiers that have been in combat with one or more ants less acceptable as food to certain ant species. Pronounced differences in chemical composition between the secretions ofN. octopilis soldiers and other members of the genus are paralleled by differences in reactions elicited from ants. No evidence of toxicity or difference in “stickiness” from soldier secretions of members of other species of the genus was obtained.N. octopilis soldiers are very slow to fire their secretion, and do not rush out when the galleries are disturbed. Instead, they remain with the workers, and, by firing sparingly, can provide protection for longer intervals than similar-sized nasutes which fire more readily. In addition, secretions of otherNasutitermes species do not seem to render their combat-veteran workers less acceptable as food items. The abundance of the other species ofNasutitermes seems to be related to the building of covered runways and durable carton nests.