Dilutions of five technical insecticides dissolved in acetone were tested for toxicity to adult tarnished plant bugs, Lygus lineolaris (Palisot de Beauvois), collected in Dallas County, Texas, a region of high insecticide use. LC(50), and LC(90) values were determined for the field-collected insects. Methomyl was the most toxic compound at both 24 and 48 hr after initial exposure. Tarnished plant bugs from a colony originating in north Arkansas, an area of low insecticide use, were exposed to three of the five compounds. The percent mortality for the Arkansas insects was different than that of the Dallas insects.