The adult moth vial testing technique has been used successfully to monitor susceptibility differences of Heliothis virescens (F.) populations. However, there are currently no data which relates these results with expected activity of commercially used pyrethroid field rates on adults and more specifically, on larvae. Studies were established to compare susceptibility of adult moths to cypermethrin using vials treated with standard rates (5, 10, 30, 50, 100 ug/vial) and with a range of field rates (0.000625, 0.00125, 0.0025, 0.005, 0.01, 0.02, 0.04, 0.06 lb ai/A). Results indicate that rates of 163 to 224 ug/vial are required to produce equal adult mortality to 0.067 to 0.077 lb ai/A. Susceptibility of adults and larvae from this same population was also compared using glass petri dishes treated in the field with sprays of cypermethrin at various rates (backpack sprayer - 0.00125, 0.0025, 0.005, 0.01, 0.02, 0.04, 0.08, 0.10 lb ai;a; Aerial 0.04 and 0.06 lb ai/A). Mortality produced by backpack and aerial sprays was similar. A very high correlation (r = .99) was obtained for moth and neonate larval mortality. However, LC-50 and LC-90 values for adults and neonate larvae were less than those obtained for older, first instar larvae.