Field surveys utilizing black light and adhesive traps made during the summers of 1969 and 1970 to determine emergence patterns of adult Glyptotendipes lobiferus (Say) from the Holyoke canal system indicated that emergence peaks may occur irregularly from mid-April through mid-September. Emergence patterns, swarming, mating and oviposition data of the species are reported for the first time. A positive phototaxis of emerging pharate adults is reported for the first time in the Chironomidae. Swarming at dusk and dawn was initiated by natural light intensities of 6 to 9 foot candles. Mating occurred in flight in the dawn swarms and averaged 6 seconds. Solitary pairs mated after dark. Mating occurred near the water surface upon female emergence and lasted 1 second or less. Oviposition involved extrusion of a dense egg mass 3 to 5 mm long onto the hind legs, followed by a flight during which the egg mass was deposited in the water. In the laboratory egg masses were observed to swell and resulted in a gelatinous mass about 13.5 mm long. Length of the egg stage at 22-25 F. and length of life of mated females at this temperature was 3 days.