Three levels of visible feeding damage of alfalfa plant-tips byHypera brunneipennis(Boheman) larvae were analyzed for quantitative and qualitative differences. No significant differences in quantitative losses existed between the moderate damage (M) and no visible damage (N) categories, but were found between these and the severe damage (S) category. Differences in such nutritional components as modified crude fiber, protein, calcium, and phosphorus existed among various of the damage categories. From these findings, the visual-damage level insecticide-treatment indexes similar to in magnitude or less than our M category, which are commonly used at present for the closely-related speciesH. postica(Gyllenhall), are criticized in terms of potential pesticide abuse. Sampling problems associated with visual indexes are discussed, and it is recommended that research on development of economic thresholds forHyperafocus on quantitative evaluation of the larval population itself rather than on visual damage patterns.