Our objective was to examine the pattern of agonistic behavior observed among 11 colonies of the Formosan subterranean termite, Coptotermes formosanus Shiraki, collected from two locations in New Orleans, LA. In 24-h petri dish tests, 13 of the 40 colony pairs displayed agonism in at least one replicate. In 14-d tests conducted in sand-filled foraging arenas, seven of the nine colony pairs tested showed agonism, including three that had showed agonism in the 24-h test and four that had not shown any agonism in the 24-h test. In tests in which individual behavior was observed for 1 h, there was variation in the prevalence of aggressive behavior shown by individual workers. This study shows that interactions between colonies of C. formosanus from the same geographic area are complex and that these interactions could influence strategies for termite control.