Noctuid moths with tympanal organs perform a series of evasive maneuvers when exposed to bat-like ultrasounds. In this paper, we tested the hypothesis that certain ultrasound frequencies are environmental stress factors that have physiological effects on noctuid moths. The effects of ultrasound produced from a commercial device on the antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and peroxidase (POX), were investigated in the adults, pupae, and larvae of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae). Our results showed that the effects of ultrasound-stress on antioxidant enzymes depended on the developmental stages of H. armigera and the duration of exposure. A significant (P < 0.01) increase in POX activity in adult and larval H. armigera was observed 40 minutes after ultrasound exposure. The results indicated that ultrasound stress has the potential to alter the antioxidant enzyme system in H. armigera.