The insecticidal activities of a series of aminothio derivatives of methomyl were investigated. In general, the spectrum of activity of the compounds closely paralleled that of the parent, methomyl, often being equitoxic to the southern armyworm (Spodoptera eridania Cramer), cabbage looper (Trichoplusia ni Hubner), cotton bollworm (Heliothis zea Boddie), tobacco budworm (Heliothus uirescens Fabricius), and boll weevil (Anthonomus grandis Boheman) but less active against the house fly (Musca domestica L.) and house cricket (Acheta domesticus L.). Additional biological parameters of a single compound, U-46,855, methyl [ [ [methyl-(4-morpholinothio)amino]carbonyl]oxy]ethanimidothioate, were compared to those of methomyl in the laboratory. U-46,855 demonstrated a marked increase in foliar residual life, lower mammalian toxicity, and greater crop selectivity while methomyl was much more resistant to mechanical loss due to rain. Evaluation of chemicals for the control of the bollworm complex in Alabama demonstrated that U-46,855 produced significantly higher cotton yields than methomyl.In recent years certain substituents attached to the carbamate nitrogen of N-methylcarbamate insecticides have resulted in the production of compounds with improved ancillary properties over the parent. Certain arylthio and acyl derivatives of carbofuran, propoxur, carbaryl, aldicarb, and other N-methylcarbamates exhibit reduced mammalian toxicity and, in some cases, increased insecticidal activity (Reay and Lewis, 1966: Brown and

derivatives of methomyl. Results of those investigations are reported in the following paper (Dutton et al., 1981).