A study was conducted to study development ofHeliothis virescens(F.),Heliothis subflexa(Guenee), and their hybrid progeny.H. virescenscompleted the larval stage in 18.2 days andH. subflexain 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. subflexafemales mated readily withH. virescensmales. 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. F1males 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 controlH. virescens.Progeny were not obtained from the reciprocal matingsH. virescensfemales withH. subflexamales. Progeny from F1females mated withH. virescensmales did not show a differential development rate for males or females.