Periodic swarming ofCryptotermes brevisWalker was observed in late May and early June from 1968 to 1971, but no fall swarms were seen. Seasonal swarming apparently was related to rainfall, although daily swarming was not. The phenomenon was crepuscular, with peaks occurring about 30 minutes after sunrise and 80 minutes after sunset. Daily swarming did not seem to be related to wind or tides, but appeared to correlate with daily fluctuations of temperature, humidity, and barometric pressure. Observed light-source preference was for sunlight, ultraviolet, and incandescent, in that order. Maximum light intensity in the vicinity of actively swarming alates was 0.05–3 foot-candles. The sequence of swarming behavior included: departure from colony, dispersal flight with positive phototaxis, landing and substrate investigation, dealation, negative phototaxis, and pairing, which included a tandem behavior. Calling behavior also was observed. Dealation was nearly instantaneous. Tandem behavior of male behind female was consistent for 10 observations. Swarming was short-term dispersal rather than long-range flight. Maximum observed flight height and duration were 30 feet and three minutes, respectively.