Bean weevil

Bean weevils
Acanthoscelides obtectus
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Coleoptera
Suborder:	Polyphaga
Infraorder:	Cucujiformia
Superfamily:	Chrysomeloidea
Family:	Chrysomelidae
Subfamily:	Bruchinae Latreille, 1802
Genera
About 1,350 species; see text.
Diversity
58 genera

Damage to beans by larvae of the
common bean weevil, Acanthoscelides obtectus

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 for most of their lives inside a single seed. The family includes about 1,350 species found worldwide.

Bean weevils are generally compact and oval in shape, with small heads somewhat bent under. Sizes range to 1 mm, up to 22 mm for some tropical species. Colors are usually black or brown, often with mottled patterns. Although their mandibles may be elongate, 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.

Host plants tend to be legumes, but species will also be found in Convolvulaceae, Arecaceae, and Malvaceae, and several species are considered pests.

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.

The adult beetles are occasionally found in the United Kingdom when they emerge out of stored products in warehouses and dwellings, but they cannot proliferate in unheated buildings in that climate.

Genera

This list of genera follows the old systematics, when the family Bruchidae was still valid.[1]

• Rhaebinae Chapuis, 1874

• Rhaebus Fischer von Waldheim, 1824

• Pachymerinae Bridwell, 1929

• Pachymerini Bridwell, 1929

• Pachymerus Thunberg, 1805
• Butiobruchus Prevett, 1966
• Caryobruchus Bridwell, 1929
• Caryoborus Schoenherr, 1833

• Caryedonini Bridwell, 1929

• Mimocaryedon Decelle, 1968
• Caryedon Schoenherr, 1823
• Caryotrypes Decelle, 1968
• Aforedon Decelle, 1965
• Exoctenophorus Decelle, 1968

• Caryopemonini Bridwell, 1929

• Protocaryopemon Borowiec, 1987
• Diedobruchus Pic, 1913
• Caryopemon Jekel, 1855

• Amblycerinae Bridwell, 1932

• Amblycerini Bridwell, 1932

• Amblycerus Thunberg, 1815

• Spermophagini Borowiec, 1987

• Zabrotes Horn, 1885
• Spermophagus Schoenherr, 1833

• Eubaptinae Bridwell, 1932

• Eubaptus Lacordaire, 1945

• Kytorhininae Bridwell, 1832

• Kytorhinus Fischer von Waldheim, 1809

• Bruchinae Latreille, 1802

• Bruchini Latreille, 1802

• Bruchus Linnaeus, 1767

• Megacerini Bridwell, 1946

• Megacerus Fahraeus, 1839

• Acanthoscelidini Bridwell, 1946

• Gibbobruchus Pic, 1913
• Ctenocolum Kingsolver & Whitehead, 1974
• Caryedes Hummel, 1827
• Meibomeus Bridwell, 1946
• Penthobruchus Kingsolver, 1973
• Pygiopachymerus Pic, 1911
• Merobruchus Bridwell, 1946
• Acanthoscelides Schilsky, 1905
• Mimosestes Bridwell, 1946
• Stylantheus Bridwell, 1946
• Altheus Bridwell, 1946
• Pseudopachymerina Zacher, 1952
• Neltumius Bridwell, 1946
• Stator Bridwell, 1946
• Sennius Bridwell, 1946
• Megasennius Whitehead & Kingsolver, 1975
• Algarobius Bridwell, 1946
• Scutobruchus Kingsolver, 1968
• Rhipibruchus Bridwell, 1932
• Pectinibruchus Kingsolver, 1967
• Dahlibruchus Bridwell, 1931
• Cosmobruchus Bridwell,, 1931
• Lithraeus Bridwell, 1952
• Bonaerius Bridwell, 1952
• Spatulobruchus Borowiec, 1987
• Palpibruchus Borowiec, 1987
• Specularius Bridwell, 1938
• Acanthobruchidius Borowiec, 1980
• Palaeoacanthoscelides Borowiec, 1985
• Horridobruchus Borowiec, 1984
• Callasobruchus Pic, 1902
• Bruchidius Schilsky, 1905
• Salviabruchus Decelle, 1982
• Sulcobruchus Chujo, 1937
• Parasulcobruchus Anton, 1999
• Borowiecus Anton, 1994
• Megabruchidius Borowiec, 1984
• Conicobruchus Decelle, 1951
• Kingsolverius Borowiec, 1987
• Decellebruchus Borowiec, 1987
• Margaritabruchus Romero & Johnson, 2001

See also

• Caryobruchus gleditsiae

References

• 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)