The effect of induced resistance and host phenology of cotton (Gossypium hirsutum L.), velvetleaf (Abutilon theophrasti Medicus), Carolina geranium (Geranium carolinianum L.) on the larval susceptibility of Helicoverpa zea (Bodd.) and Heliothis virescens F. to Heliothis zea Nuclear Polyhedrosis Virus (HNPV) was studied. Induced resistance in cotton enhanced the H. zea and H. virescens larval susceptibility to HNPV. Host phenology of cotton, velvetleaf and Carolina geranium significantly (P<0.05) affected the larval susceptibility of both species to HNPV. H. virescens larvae was more susceptible to HNPV than the H. zea on cotton and Carolina geranium while H. zea was more susceptible to HNPV than H. virescens on velvetleaf.