Abstract The lough consisted primarily of annual bluegrass (60%), Kentucky bluegrass (30%), and perennial ryegrass (10%). Treatment plots were 9 × 6 ft, arranged in a randomized complete block design and replicated 3 times. Liquid formulations were applied by using a C02 sprayer with 4 8004VS Teejet nozzles mounted (m a 6-ft boom, operating at 28 psi and delivering 5 gal/1000 sq ft. At treatment time, the following soil and environmental conditions existed: air temperature, 65°F; soil temperature, 64°F; RH 77%; amount of thatch, 0.25-1.0 inches; soil type, loam; soil size separation, 36.2% sand, 47.6% silt, 16.2% clay; soil moisture, 13.0%; soil pH 5.7; % organic matter, 3.7; water pH, slightly acidic; 9.0 inches of rainfall was recorded over the posttreatment period. The experimental area was not irrigated after treatment. Posttreatment counts were made 32 days later (2 Oct). Six sq ft sod samples were randomly taken from each replicate, and the total number of northern masked chafer grubs/sq ft was recorded.