Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) is a well-known polyphagous insect pest. Mating compatibility among the insects occurring on different host plants is essential for free gene flow among populations. We tested the extent of crossability and fecundity of the insects that survived onBacillus thuringiensis (Bt) cotton with those occurring on pigeon pea,Cajanus cajun (L.) Millsp., non-Bt cotton,Gossypium hirsutum L.; sunflower,Helianthus annuus; sorghum,Sorghum bicolor L. Moench.; okra,Abelmoschus moschatus Medikus; chickpea,Cicer arietinum L.; marigold,Tagetes spp.; and tomato,Lycopersicum esculentum L., crops. The insects from different crops were freely crossable with those collected from Bt cotton and among themselves. The average fecundity across different crosses ranged from 314.1 to 426.3 in direct and from 305.8 to 421.7 eggs per female in reciprocal crosses. In any given cross, a minimum of 85.89% egg hatch was recorded. Furthermore, the F₁ individuals of different cross combinations were found to cross freely with their parents (BC₁) and among themselves with similar fecundity and egg hatch. High crossability amongH.armigera occurring on different host plants suggests that crop mosaics that may exist in countries such as India could play an important role as natural, nonstructured refugia and prolong the durability of the genes deployed for controlling this insect.