Extracts of the intact hairpencil glands and hairs from the hairpencil glands of males ofHeliothis virescens (F.) were analyzed by capillary gas chromatography (GC) and by GC-mass spectroscopy. These analyses indicated that hexadecanyl acetate (212.4 ng/male), hexadecanol (22.3 ng/male), (Z)-11-hexadecenyl acetate (3.5 ng/male), octadecanyl acetate (14.2 ng/male) octadecanol (7.5 ng/male), tetradecanoic acid (2.7 ng/male), hexadecanoic acid (22.3 ng/male), and octadecanoic acid (6.5 ng/male) were present in the extracts. These compounds also were found in volatiles released from the hairpencil glands. In addition, GC analysis using both polar and apolar capillary columns indicated that extracts of the glands and extracts of the hairs from the hairpencil glands contained small amounts of tetradecanyl acetate, (Z)-9-tetradecenyl acetate, tetradecanol, (Z)-7-hexadecenyl acetate, (Z)-9-hexadecenyl acetate, and (Z)-11-hexadecenol. No (Z)-9-tetradecenal was present. Studies indicated that titers of the compounds increased rapidly during the 36 hr after adult eclosion and then leveled off, being maintained at high levels until released when the glandular hairs were exposed. During exposure of the hair pencils substantial amounts of the compounds were released. In vivo application of 500 ng of suspensions of (Z)-11-hexadecenyl acetate, (E)-11-hexadecenyl acetate, (Z)-11-tetradecenyl acetate, or (E)-11-tetradecenyl acetate in dimethyl sulfoxide to the surface of the denuded hairpencil gland showed that biosynthesis proceeds to the alcohol via the acetate.