A survey and laboratory experiments were conducted on incidence rates and economic impact of Eucarazzia elegans (Ferrari) (Hemiptera: Aphididae) in Salvia officinalis L. (Lamiaceae). The investigations were purposively performed on conventionally grown common sage in Bornova and Menemen, Izmir-Turkey. Experiments were set up with zero, normal and double population densities of the aphid. The corresponding treatments 0 (no exposure), 2, 4, 6, 8, 10 and 12 weeks (complete exposure) were used for evaluating economic impact. Eucarazzia elegans infested old leaves with an incidence rate of 9.5% in the early spring and then migrated to young leaves and blossom at the beginning of the summer with the incidence rate of 1.1%. The seasonal distribution of the aphid was affected more by temperature than humidity and rainfall. Although the aphid infestation had no differences on the quantity of the essential oil, some of the essential oil components were markedly different from the control. The total plant weights (fresh and dry) with the normal and double infestation rate were decreased about a third and more than a half compared to the control, respectively. Aphids feeding on common sage beyond 8-10 weeks caused more than 50% yield loss. The highest cost-benefit ratio was achieved in plots where six insecticide applications were made.