Calling by female Lambdina fiscellaria lugubrosa (Hulst) occurred when terminal abdominal segments 8–10 were protracted, exposing an enlarged region in the intersegmental membrane between segments 8 and 9. Histological examination of this region disclosed paired glands situated ventrolaterally in the eighth segment. The glands were presumed to be pheromone glands, and differ from those described for other Lepidoptera, in their paired structure and ventrolateral position. More males were attracted to traps containing virgin females than to empty control traps, but only during the first half of the moth flight. Board and yellow carton sticky traps were superior to 3M and white carton traps. Behavioral observations suggested that the sex pheromone may serve as an excitant as well as, or instead of, an attractant, stimulating the male to searching activity.