Aceria malherbaeNuzzaci (Acari: Eriophyidae), was imported from Greece to the United States and released in 1989 near Bushland, TX, as a potential biological control agent for field bindweed,Convolvulus arvensisL. (Convolvulaceae). The number of gall mite-infested crowns increased from 2.0/m2in September 1989 to 9.5/m2in June 1991 but decreased to 4.0/m2in June 1992. In September 1991, 76.0% of the crowns were infested, and the gall mites had moved 9.6 m from the plot. Gall mites overwintered on rhizomes 0.1–6.0 cm beneath the soil surface, but 63.1% of those recovered were found in the top 1.0 cm of soil. This represents the first successful establishment of an introduced arthropod for biological control of a crop weed in the United States. The mite is now being released on field bindweed in South Dakota, New Jersey, and Oklahoma.