Abstract Diazinon at standard rates and in a split application was compared with four other insecticides for control of white grubs on a fairway. The only species present during the test was Japanese beetle. Treatments were applied 25 Aug in a completely random design and replicated 4 times. Plot size was 10 × 10 ft. Liquid formulations were applied in 1 gal of water with a hand-held sprinkling can; granules were applied with a hand shaker. All plots were irrigated with fairway sprinklers about 2 h after treatments were applied; about 2 gal of water was used/plot. The second application of Diazinon was applied 1 wk after the initial application. Environmental and soil conditions at treatment time were as follows: air temperature, 68°F, soil moist; soil temperature 70°F (4 inches), soil pH 6.2; organic matter, 5.5%; thatch layer Vs to l4 inches. Four locations on each plot were sampled using a cup changer (4.25 inches diam).