Heptachlor, lindane, and methyl parathion granules, each at rates of 1 and of 5 pounds per acre of actual toxicant, were applied in early May to Du Puits alfalfa in its first cutting year. The total length of the clover root curculio ( Sitona hispidula (F.)) larval feeding scars per tap root was reduced by heptachlor and lindane treatments, each at 1 and at 5 pounds per acre, when the results were based on six roots taken systematically from each plot in August. Only the 5-pound rates of heptachlor and lindane showed significant reduction in larval feeding scars when two roots were taken from each plot. The two-roots-perplot procedure was biased by selecting only plants with vigorous or abundant foliar growth. Additional results indicated that the vigor of the plant and possibly the size of the tap root could be important sources of variation to consider in the evaluation of larval injury. Supplementary counts taken by collecting by insect net 35 days after treatment of the plots showed that heptachlor at 1 and at 5 pounds and methyl parathion at 5 pounds per acre gave significant control of the clover root curculio adult.