The abdominal and thoracic odoriferous glands of adult flour beetles, Tribolium castaneum (Herbst), T. confusum J. du V., and T. destructor Uyttenb., contain a pungent, irritating liquid (Roth, 1943; Palm, 1946). Flour in which the beetles have built up a large population becomes pink in color due to contamination by this secretion (Chittenden, 1896; Payne, 1925; Chapman, 1926). This substance has been variously described as similar to cresols and phenols (Palm, 1946), aldehydes (Chapman, 1926), and quinones (Roth and Howland, 1941). Roth and Howland (1941) isolated the odorous material of T. confusum by passing dry air into a flask containing the beetles and then through a dry-ice trap in which the secretion collected as yellow-brown crystals. At room temperature the substance was a fairly volatile liquid with a pungent, quinone-like odor; it reduced KI starch paper readily.