Abstract
Monitoring Heliothis populations for 2 years on four spring weed hosts revealed that crimson clover, Trifolium incarnatum L., and Carolina geranium Geranium carolinianum L., supported many more Heliothis than vetch, Vida spp. L., or toadflax, Linaria canadensis L., and that peak population densities occurred on crimson clover earlier than on Carolina geranium. Heliothis mortality and larval parasitism were higher at one study site than at the other, and the parasitoids Microplitis croceipes (Cresson) and Campoletis flavicincta Viereck predominated. The importance of spring weeds for the population buildup of Heliothis and certain parasitoids could be instrumental in the decisions involving weed removal and early-season pest destruction.