Natural mortality of the bollworm in Texas High Plains cotton

The cotton bollworm, Helicoverpa zea (Boddie)and the closely related tobacco budworm, Heliothis virescens (Fabricius) are serious pests of many crops throughout the Americas. Together with related species from the nocluid subfamily Heliolhidinae, they comprise a group of agricultural pests that damage a wide variety of food, fiber, oil, horticultural, fodder and omamental crops in virtually every comer of the world (Fill 1989). This group of pests occurs worldwide, and can be found on virtually all of the land masses banded by 50 degrees North latitude and 50 degrees South latitude (Quaintance and Brues 1905). Permanent populations exist between 40 degrees North and South latitude (Fill 1989). Representatives of the group are even found on many islands of the Pacific Ocean (Hardwick 1965).