The response of adult tarnished plant bugs, Lygus lineolaris (Palisot de Beauvois), to sticky traps baited with virgin males or females was studied in 1997 and 1998. Male-baited traps captured significantly higher number of males than unbaited check traps in 1997, and in 1998 they captured a 4-fold higher number of males than the check traps. Male-baited traps also captured a significantly higher number of females than the check traps in 1997, and in 1998 they captured a 2-fold higher number of females than the check traps. Female-baited traps did not capture significantly higher numbers of females than were captured in the check traps in either year. These results indicated that the male tarnished plant bug may produce an aggregating pheromone that is attractive to both sexes.