Seasonal changes in captures of cotton bollworm (CBW), Heliothis zea (Boddie) and tobacco budworm (TBW), H. virescens (F.) in pheromone traps in irrigated and dryland cotton were investigated in 1987-89 in the Brazos River Valley in several producer fields close to College Station, Texas. CBW moth captures were higher than TBW moths in both dryland and irrigated cotton. CBW captures were highest in July and decreased in August, while TBW captures showed one small peak in July and one or two larger peaks in August. Median CBW moth captures (50% cumulative catch) in traps occurred later in irrigated cotton than in dryland cotton. There was no consistent pattern in duration of captures of CBW and TBW moths in traps between irrigated and dryland cotton as measured by the length of time between cumulative catch reaching 10 and 90%.