Definitive information was obtained on actual numbers of native moths in an experimental area. The information was obtained for use in future experiments on determining the feasibility of employing the sterile male trait to suppress natural populations of Heliothis virescens. The last two years of a three year study were carried out with releases of known numbers of reared marked moths in a test area covering 25 square miles during the period of the normal spring F₁ population. Calculations were made on numbers of known released moths and ratios of released to feral moths captured. Studies during 1982 and 1983 indicated populations of 2.17 and 3.85 moths eclosing per acre, respectively, during April and May in the central Mississippi Delta study area.