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Boll Weevil

Anthonomous grandis, the insect that changed the face of agriculture in the South

boll weevil, the tiny holes on the cotton boll are where it fed

Description

The adult boll weevil is about 1/8 to 1/2 inches long, not including a very conspicuous snout that is about half as long as the body. It is usually reddish or grayish brown in color, but the color varies according to age and size. It is distinguished from other weevils by a double-toothed spur on the inner surface of each front leg.

Distribution

Originally native to Mexico, the boll weevil spread into Texas in the late-1800's, and through the rest of the "cotton belt" by the 1910's. It has also spread south into Central America.

Life Cycle

Boll weevils feed and reproduce exclusively on cotton and very closely related tropical plants. Adults overwinter in leaf litter and "waste areas" surrounding cotton fields, and emerge and fly into those fields in the spring. They feed on the flowering structures of the cotton plants for 3-7 days before mating, after which each female will deposit up to 200 pearly white eggs (each egg is deposited singly in a small cavity puntured into the structure). The tiny, legless, white grubs emerge in 2-1/2 to 5 days, depending on temperature, and immediately begin feeding on the flowering structure in which they were born. Grubs grow fairly rapidly, reaching a length of about 1/2 within 7-14 days, depending on quality of the cotton plants upon which they have been feeding, at which time they enter the pupa stage, which lasts 4-6 days. With each generation of boll weevil only requiring, at most, 1-1/2 months to go from egg to sexually mature, there can be as many as seven generations in any given year. The females of each successive generation will lay fewer eggs, however, since each new generation will have fewer healthy cotton plants to feed and reproduce on.

Other Information

A single generation of boll weevils can totally decimate a cotton field, and the numerous generations possible in any given growing season can easily destroy a cotton-based economy. The invasion of the boll weevil into the "cotton belt" forced many cotton growers to either find new crops or go bankrupt, which is why the city of Enterprise, Alabama, erected a monument to the pest.

Boll Weevil Monument in Enterprise, Alabama

Scientific Classification

phylum Arthropoda
class Insecta
order Coleoptera
family Curculionidae
genus and species Anthonomous grandis

SEE ALSO
Cotton

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This page was last updated on July 29, 2017.