Heliothis virescens(F.) is a polyphagous pest on cotton, soybean, and tobacco andH.subflexais a monophagous nonpest onPhysalisspp. Oviposition choices of the reciprocal F1hybrids or these two species were compared with those of the parental strains to determine Sex linkage, quantify niche breadth, and rank host preferences. Strains ofH.virescens, H.subflexa, and the reciprocal F1hybrids (SVoand VSo) were each, offered a choice of four plants on which to oviposit (cotton, soybean, tobacco, andPhysalis angulata). Host preferences were ranked based on the proportion of eggs laid on each hostH.virescensoverwhelmingly preferred tobacco,H.subflexapreferredPhysalis, and SVoand VSopreferred tobacco. There were no significant differences among strains in their responses to cottOn and soybean. Because SVoand VSohad similar patterns of preference across hosts, there was no indication or Sex linkage. Niche hreadth, a measure of the degree of specialization, was calculated for each strain. Under greenhouse conditions,H.cirescenshad the narrowest ovipositional niche andH.subflexaand the hybrids had broader niches and were similar to each other. When a novel host (Oenotherasp.) was offered to the strains, there was 110 difference in the responses among strains nor were there changes in preference ranks or diet breadth. The hybrid, despite a major genetic reorganization relative to the parents, did not behave in an unpredictable way.