The female yellowheaded fireworm produces a pheromone to attract males. GC analysis of washes of ovipositors of single virgin females revealed eight compounds that were identified by microchemical techniques and comparison with authentic materials. (E)-11, 13-Tetradecadienal, (Z)-11-tetradecen-1-ol acetate, (E)-11-tetradecen-1-ol acetate, 1-tetradecanol acetate, 2-pentadecanone, 2-heptadecanone, (E)-11, 13-tetradecadien-1-ol acetate, and hexadecanal. Field tests indicate that only (E)-11, 13-tetradecadienal is required to capture males, and thus this compound represents a female sex pheromone of the species.