A low-frequency, sodar (sound detecting and ranging) set was designed, constructed, and tested in cotton fields to detect flying tobacco budworm moths attracted at night to sex attractant dispensed from the sonic transmitter site. Counts made by the sodar set were compared with numbers of male budworms caught in traps baited with either synthetic pheromone or live female moths. Peak sonic transmission power was<25 W/2 ms at a 1.2% transmit-receive duty cycle. With sensitivity set at an effective range of 1 meter, the majority of moths counted by the battery-powered sodar set were tobacco budworms when their synthetic sex attractant was used as bait.