The grape thripsDrepanothrips reuteriUzel, was not abundant in the primary bloom clusters of Thompson Seedless grapes and was not associated with scarred fruit. It was the only thrips abundant on Thompson Seedless foliage. Leaves that were infested with the grape thrips grew distorted. The population in the foliage may have been regulated by the type of interrow ground treatment, irrigation method, and type of rootstock, when these cultural practices had a direct effect on the vigor of the vines. Growing vines appeared to support greater populations of thrips. When the number of grape thrips was compared on leaves in different positions along the cane, most of the thrips were found on the young foliage near the growing end. The grape thrips was a chronic inhabitant of the foliage and existed in such low endemic numbers that control of the species was considered unnecessary.