Adult : Elongate, oblong and flattened body, shiny black in colour, about 8-9mm long, with the prothorax distinctly separated from the rest of the body by a loose, prominent joint. Larvae : fleshy, white to greyish-white with black head and black plate with two horny black projections at the tip of the abdomen, up to 19mm long.

Eggs (about 1,000) laid loosely, sometimes also in clusters or packed in crevices in flour, grain, or other foodstuff. Larvae hatch in about 10 days and larval period may extend from 38 to 400 days depending on conditions. The life cycle may be as short as 70 days, but it may be much longer under conditions unfavourable to the insect''''s development. The females generally live for a year, but have stayed alive for more than 3 years in lab conditions. Pupation takes 8-25 days.

One of the largest grain-infesting beetles, can go without food for 52 days (adults) to 120 days (larvae). Larvae feed on a great variety of grains, as well as on flour, meal, biscuits and bread, vegetables, dried fruits, etc. When attacking grains such as wheat and oats, larvae usually confine themselves to the embryo, this being the softest part. Upon migrating from its food source in order to pupate, it occurs accidentally in such unusual places as books, balls of twine, carpet rolls, rugs and in bottles of milk. Also a serious pest in tobacco factories, it is found in bales of dry tobacco where it is claimed to bore in search of insect larvae. It then pupates or hibernates by hollowing out a cell in the adjacent wood and can remain in the wood or empty bins for months to emerge and re-infest fresh grain placed in these bins. This wood-boring habit of the larvae has resulted in the pupal chamber being excavated in such curious places as the corks of bottles and in books.