Fourteen organophosphorus insecticides have been evaluated for the control of the current borer, Ramosia tuplifurmis (Clerck). The evaluation included field studies supplemented by laboratory trials to determine whether the insecticides performed as ovicides. It included also studies of larvacidal action as well as a study of residual breakdown of parathion. Of the insecticides tried parathion proved to be the most effective. The ethyl and methyl parathion mixture, Metacide,® O,O-dimethyl O-p-nitrophenyl phosphorothioate, parathion mixture, was about as effective as parathion. Although tried in only one season, Bayer 25141, O,O-diethyl O-p-(methylsulfinyl)phenyl phosphorothioate, compared favorably with parathion. EPN and the other insecticides gave fair to poor control. As an ovicide parathion was superior to all the other materials except diazinon and Metacide. A deposit of 93 μg of parathion per 100 cm2 of currant shoot surface gave 95% kill of eggs. Dosages at this level killed the eggs whether it was applied directly to the eggs or the eggs were laid on treated bark. Much of the effectiveness of parathion is apparently due to the retention of the deposit by the bark of the shoots. Bark deposits weather much less rapidly than do deposits on the fruit. In general the data shows a close relationship between the effectiveness of the insecticide in the field and the ovicidal performance as determined in the laboratory. Compounds giving good control in the field were also toxic to the eggs. As applied for currant borer control parathion sprays laid down deposits of about 14 ppm on the fruit. Within 2 weeks this deposit weathered to less than 1 ppm. Rainfall of 0.5 to 0.91 in within 1 day after application reduced the deposits on fruit by as much as 85%.