Since its reported arrival in Texas during the spring of 1986, the Russian wheat aphid, Diuraphis noxia (Mordvilko), has increased its range to include all of the 17 western States and 3 Canadian provinces and has caused serious economic damage to the U.S. wheat. Triticum aestivum L., and barley, Hordeum vulgare L., industries. Research programs directed toward the control and management of D. noxia populations in North America have produced much information on the biology of this pest. D. noxia growth and development occurs at temperatures between 5 and 30°C. Generations telescope over the summer, leading to dramatic population increases during a remarkably short period of time. D. noxia is a typical r-strategist that exhibits annual population fluctuations throughout its range in North America. These fluctuations are typified by seasonal expansions through colonization of newly emerged cereals followed by retractions into widely separated populations on noncultivated grasses and volunteer wheat and barley during the intervening period between crops. D. noxia is anholocyclic in North America and overwinters in close association with its host plant. Aphid populations often decline during cold temperatures because reproduction ceases. The most important noncultivated hosts appear to be crested wheatgrass. Agropyron cristatum (L.) Gaertner, and Canada wildrye, Elymus canadensis (H.). The ability of D. noxia to induce rolled leaves and thereby creating a leaf-gall niche appears critical to its success. D. noxia manipulates plant growth and development, causing alterations in the carbohydrate partitioning patterns of wheat whereby the sink-to-source transition of the infested rolled leaf is delayed and a protracted assimilate-sink status is maintained at the feeding site. Biotypic variation has not been detected; however, populations should be regularly monitored for biotype development because of the potentially serious threat they pose to the durability and usefulness of newly developed resistant cereal cultivars.