A study was conducted to study development of Heliothis virescens (F.), Heliothis subflexa (Guenee), and their hybrid progeny. H. virescens completed the larval stage in 18.2 days and H. subflexa in 16.7 days. No differences were observed between sexes in rate of larval development in either species. In attempts to hybridize the 2 species, H. subflexa females mated readily with H. virescens males. Eggs were fertile and larvae emerged. Males from this mating required 15.1 days, as contrasted with 17.7 days for females, to complete the larval stage. F1 males were sterile; females were completely fertile. These sterile males may be separated either on the basis of time of pupation or the basis of weight for a sterile release program to control H. virescens. Progeny were not obtained from the reciprocal matings H. virescens females with H. subflexa males. Progeny from F1 females mated with H. virescens males did not show a differential development rate for males or females.