The formamidines chlordimeform (CDF), desmethyl-CDF, BTS27271 (NOR-AM 49844) and amitraz, as well as the pyrethroid lambda-cyhalothrin and the carbamate thiodicarb, were evaluated for ovicidal activity and effects on octopamine titers in eggs of the tobacco budworm, Heliothis virescens (F.). lanibda-Cyhalothrin and CDF were the most active of the compounds examined followed by BTS-27271 and desmethyl-CDF. Although octopamine was not detectable in untreated tobacco budworm eggs, CDF, demethyl-CDF and to a lesser extent BTS-27271 all caused the appearance of measurable quantities of octopamine in treated eggs, while amitraz, which was the least toxic of the formamidines had no detectable effect on octopamine titers. lambda-Cyhalothrin and thiodicarb also had no detectable effect on octopaminc titers. In vivo metabolism studies of radiolabeled amitraz by eggs of the tobacco budworm indicated that BTS-27271 is a likely metabolite. Thus, the present study suggests that one effect associated with ovicidal activity in the formamidines is the ability to alter octopamine titers.