Quantitative studies were conducted to evaluate comparative responses of two alternate hosts,Cadra figulilella(Gregson) andEphestia elutella(Hübner), to a suspension of two nonoccluded viruses ofAmyelois transitella(Walker). Instar, weight of larvae with chronic disease, and comparative mortality of neonate larvae were determined. Although all tests indicated that the alternate hosts were highly resistant to the viruses, larvae ofA. transitellaremained highly susceptible to suspensions of virus from the alternate hosts after five serial passages.