Normal eye color of the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), is dark purplish-black. A strain homozygous for a new mutation, red eye color, was established and reared in the laboratory for >5 yr. The mutant phenotype is controlled by a single autosomal recessive allele. The gene symbol assigned to this new mutant is r. Laboratory tests showed that egg production and egg viability in the red-eye mutant females were not different from that of normal-eye females. Expression of the red-eye mutation was not found in extensive samples of wild populations in the Mississippi River Delta, and was rare in populations near Crossett, AR, where the original mutant was found. The mutant strain could be of use as a genetic marker in studying reproductive behavior and population dynamics of this important pest species.