Approximately 75 species of Artemisia, or sage, occur in the Rocky Mountain region, many of these being infested by aphids, often to a considerable extent. The great economic importance of several specis of Artemisia as food for range livestock and the incomplete knowledge of the aphids attacking them in Utahled the writers to undertake this study. Most of the report deals with the apterous forms which are most frequently encountered and which possess good specific characters for identification.