The bean weevils or seed beetles are a subfamily (Bruchinae) of beetles, now placed in the family Chrysomelidae, though they have historically been treated as a separate family. They are granivores, and typically infest various kinds of seeds or beans, living most of their lives inside a single seed. The subfamily includes about 1,650 species and are found worldwide.
Bean weevils are generally compact and oval in shape, with small heads somewhat bent under. Sizes range from 1 to 22 mm for some tropical species. Colors are usually black or brown, often with mottled patterns. Although their mandibles may be elongated, they do not have the long snouts characteristic of true weevils.
Adults deposit eggs on seeds, then the larvae chew their way into the seed. When ready to pupate, the larvae typically cut an exit hole, then return to their feeding chamber. Adult weevils have a habit of feigning death and dropping from a plant when disturbed.
One characteristic of the beetles which can be seen in the photo is that the elytra are short, not quite reaching the tip of the abdomen.
Several species are native to Great Britain, but there are also records of several introduced species from stored products in warehouses and dwellings, although these species cannot proliferate outside of heated buildings in that climate.
Genera
This list of genera uses the new classification, treating the bean weevils as a subfamily with six extant tribes, eight or nine subtribes, and one extinct tribe. The former names and ranks for the tribes and subtribes under the old classification, treating the been weevils as a family, are given in parentheses (except for Myanmaropini, which was established only for the new classification).[5][6]
^Morse, Geoffrey (2014). "2.7.1 Bruchinae Latreille, 1802". In Leschen, R.A.B.; Beutel, R.G. (eds.). Handbook of Zoology. Arthropoda: Insecta: Coleoptera: Volume 3: Morphology and Systematics (Phytophaga). Berlin - Boston: Walter de Gruyter. pp. 189–198. doi:10.1515/9783110274462.189. ISBN978-3-11-027370-0.
John M. Kingsolver, "Bruchidae", in Ross H. Arnett, Jr. and Michael C. Thomas, American Beetles (CRC Press, 2002), vol. 2 (note that this reference itself indicates the group is a subfamily, and the change was made only after the chapter was written)
