The research described here has been directed toward the development of an olfactometer to bioassay tarnished plant bug (Lygus lineolaris Palisot de Beauvois) (TPB) sex attractant. Plans for the olfactometer, conditions under which the TPBs are held, considerations in the development of the bioassay procedure, and results from bioassays are discussed. We developed a reliable olfactometer for the project and established a bioassay procedure that generates positive male TPB olfactory responses to females.