T. freemani, which had not been captured for nearly a century, was rediscovered, in 1981, from imported corn in Japan. Before the rediscovering, there were no available information on the characteristics of T. freemani except Hinton's morphological description.
　Through the investigations of the rediscoverd population of T. freemani, several distinct facts were obtained as follows.

　1) A sibling species of T. castaneum.
　The fact of infertile hybrid progeny produced by crossing between T. freemani and T. castaneum indicates that T. freemani is a sibling species of T. castaneum. This is the first observation of a hybrid produced from T. castaneum.

　2) A potential stored product insect
　T. freemani was easily developed on the standard wheat-feed medium used for many stored product insects and successfully reared on other stored products. This fact strongly suggests that T. freemani can be a stored product insect.

　3) The prevention of pupation by crowding
　The pupation of T. freemani larvae was greatly prevented by increasing larval density. This distinct phenomenon is the first observation in the genus Tribolium.

　4) The position of T. freemani in the genus Tribolium
　In the castaneum-section, T. freemani might be a closer species to T. castaneum than to both species of T. madens and T. audax, because, beside a sibling species of T. castaneus, T. freemani did not produce any F₁ progeny in the interspecific crossing of T. freemani-T. madens and T. freemani-T. audax.
　From the characteristics summarized above, it can be concluded that: (1) T. freemani must be distributed into stored product enviroments; especially in the tropical or semitropical zones, although it seems, at present, of negligible economic importance or extremely localized. (2) As T. cctstaneum, T. freemani would be a useful insect for ecological, physiological and genetic studies as an experimental insect.