Tobacco budworm,Heliothis virescens(F.), growth rates showed a significant interaction between diet and temperature. Larvae and pupae that were reared on artificial diet were heavier than those reared on soybean and cotton, with corresponding weights being less at 20°C than at 25 and 30°C. Larvae fed soybean or cotton required seven instars to complete larval development; seven instars were required on artificial diet only at 20°C. Larval survival was 24% (20°C), 34% (25°C), and 17% (30°C) higher on soybean than on cotton. The prepupal and pupal periods were longest at 20°C and shortest at 30°C, but only the pupal period was influenced by larval diet (development shorter on soybean than on cotton at 20 and 30°C). Pupal weight for insects fed soybean increased as temperature increased, but this relationship was reversed for insects fed cotton. Preoviposition period was not significantly influenced by either diet or temperature. More eggs were laid by females at 20°C than at 25 and 30°C, with larger numbers of eggs laid by females reared on cotton than on soybean or artificial diet. Diet did not affect longevity of moths or viability of eggs, whereas increased temperatures from 20 to 30°C decreased longevity of moths and egg hatchability