Search
Christine Gambino, Carlton, Christopher E.
The boll weevil, also known as the Mexican boll weevil and southeastern boll weevil, is a historically significant pest of cotton. Adult boll weevils are small beetles varying in size from 3 mm to 9 mm in length with teardrop shaped bodies. With age the weevil’s color changes from reddish-brown to dark gray. Scales cover the surface of the body and appear more hairlike than those of many other weevils. The main visible part of the thorax (prothorax) can sometimes possess a white stripe of scales. The legs of recently matured adults possess red or black hairs that fall off over time. Adult boll weevils have long snouts or rostrums measuring about half the length of the body. The mouthparts are located at the end of the snout. Variation in the snout is the simplest way to distinguish between sexes. Snouts of female boll weevils are more slender, longer and convex when compared to those of males. Snouts of male boll weevils are rougher with divots and scales compared to those of females. Adults of both sexes possess elbowed, clubbed antennae located near the end of their snouts
Larvae are C-shaped, white and legless, with brown head capsules. Eggs are about 1 mm wide, slightly elliptical and opaque. Larvae grow to approximately 13 mm before pupating. The pupa is whitish in color, exposing the developing legs, wing pads and snout.
Two named subspecies of Anthonomus grandis occur in the U.S. The Thurberia weevil (Anthonomus grandis thurberiae) is of no economic concern and is limited to southwestern U.S. The boll weevil (Anthonomus grandis grandis) has historically been a pest of cotton throughout the cotton growing regions of southern U.S. The genus Anthonomus is enormous, with at least 120 species recorded from the U.S. and 400 described species worldwide. Misidentification of species can lead to undue anxiety and, potentially, unjustified use of pesticides. A specialist or qualified insect diagnostician should be consulted when identifying members of the genus Anthonomus, especially if boll weevil is suspected.
Boll weevils undergo complete metamorphosis (holometaboly), meaning four developmental stages: egg, larva, pupa and adult. The life cycle from egg to adult can take 16 to 67 days, depending on the temperature, with longer development times at lower temperatures. Six or seven generations may be completed annually in Louisiana. Females are known to lay more eggs during their spring emergence when temperatures are consistently above 52 F (10.8 C) but will also deposit eggs before entering diapause during winter. Prior to laying eggs, the female chews a hole in a cotton square or boll, then deposits eggs inside and seals the entrance with a solidified mixture of feces (frass) and fluid from excretory glands. Two to five days are required for the larvae to hatch. Oviposition depends on the age of the cotton plant. Females prefer half grown squares but will lay anywhere when field populations are high. Larvae feed in the cavity where they hatched, hollowing it out. They go through four larval stages (instars), requiring approximately seven to 18 days to pupate. Metamorphosis can take four to 10 days. Once completed the adult chews its way out through the original hole. Overall size of the adult weevil varies according to the nutritional condition of the host squares. Adults begin mating after three to seven days of feeding. When temperatures start dropping below 52 F (10.8 C), adults fly to nearby wooded areas to overwinter in a dormant condition (diapause). They also overwinter among cotton seeds and stalks left in fields.
The boll weevil is an invasive species from Central and South America. It was first detected during 1892 around Brownsville, Texas, after crossing the Lower Rio Grande. It soon spread across the entire cotton belt, moving up to 120 miles per year. During 1903, James Wilson, then the director of the U.S. Department of Agriculture, testified in Congress calling the boll weevil “a wave of evil,” emphasizing the problem the South was facing to the federal government. By 1922, the production of cotton had decreased by up to 80%. Estimated economic loss to American cotton producers was up to $15 billion.
The boll weevil can decimate a cotton field. Cotton is planted in the early spring, and boll weevil infestations start as soon as the plant is out of the ground. Adults feed on the leaves until the bolls form where the females lay eggs. Most damage is from larval feeding, which causes bolls or squares to blacken and fall off. Once populations build up, the weevils continue to feed until all cotton is destroyed or killed by frost. Monitoring adult densities is a valuable tool in predicting subsequent larval infestations during future growth cycles.
Due to the enormous devastation the boll weevil inflicted across the South, it became something of a cultural icon. This trend started during 1908 with Charley Patton’s song “Mississippi Boweavil Blues” and peaked with Brook Benton’s rendition of Lead Belly’s “The Boll Weevil” reaching number two on the Billboard Top 100 during 1961. The citizens of Enterprise, Alabama, erected a monument honoring the boll weevil during 1919, noting that the weevil taught them to be just as adaptable as weevils through diversification of agricultural crops. Each year in October, a Boll Weevil Fall Festival is held in Enterprise. Surprisingly, this isn’t the only statue of the creature. In 2025 the University of Arkansas, Monticello, erected two statues honoring their sports team mascot, the boll weevil. The boll weevil has appeared in songs and folklore for the better part of 150 years, firmly securing its place as America’s most notorious beetle pest.
In 2008 Commissioner of Agriculture and Forestry Mike Strain created the Louisiana Department of Agriculture and Forestry’s Boll Weevil Eradication Commission. Eradication was achieved using targeted applications of the insecticide Malathion and a species-specific pheromone trap. The last boll weevil in Louisiana was caught in 2010. Although it has been declared eradicated in Louisiana since 2011, the boll weevil program personnel continue to monitor all cotton grown in the state to prevent further incidence.
No boll weevils have been recorded in Louisiana for 15 years, but they are still a problem in the Lower Rio Grande Valley of Texas (LRGV). Last year 67 boll weevils were collected in that area. This number is down from previous years due to the fastidious efforts of the Texas Boll Weevil Eradication Program, but it remains a concern for the cotton producers in that area. The next step to prevent movement of the boll weevil into the United States is working with cotton producers on the Mexican border to implement eradication strategies into their production practices. The plan is to keep the boll weevil “lookin’ for a place to stay” (Lead Belly, 1934).
Hall S. 2013. The life and times of boll weevil. Library of Congress Blogs. (accessed 23 February 2026)
Herrick G. 1904. The Mexican cotton boll weevil. Circular No. 17. Mississippi Agricultural Experiment Station, Mississippi State University. (accessed 23 February 2026)
Jones, R.G., and M.R. Williams. 2001. A field guide to boll weevil identification. Technical Bulletin No. 228. Mississippi Agricultural and Forestry Experiment Station, Mississippi State University. (accessed 23 February 2026)
Lange F., A. Olmstead, and P. Rhode. 2008. The impact of the boll weevil, 1892-1932. The Journal of Economic History 69: 685-718.
Leigh, T.F., S.H. Roach, and T.F. Watson. 1996. Biology and ecology of important insects and mite pests of cotton. Chapter 2, In Cotton Insects and Mites Characterization and Management, (eds. E.G. King, J. R. Phillips, and R. J. Coleman). No. 3 The Cotton Foundation Reference Book Series, Memphis. (accessed 23 February 2026)
Russell, A. 2023. Boll weevil eradication most successful pest insect elimination program. Texas A&M AgriLife Digital Magazine. (accessed 23 February 2026)
Strain, M. 20, March 2012. Boll weevil eradication achieved in Louisiana. Farm Progress. (accessed 29 January 2026).
Tow, R. 2025. UAM athletics unveils new boll weevil statues. Athletic Communications. (accessed 23 February 2026).
P4043
4/1/2026
The LSU AgCenter and LSU provide equal opportunities in programs and employment.
Adult boll weevil, dorsal view. Photo by Mike Quinn, Bugguide.net
Adult boll weevil, lateral view. Photo by Louisiana State Arthropod Museum
Boll weevil larva and pupa inside damaged cotton boll. Photo by Clemson University, U.S. Department of Agriculture Cooperative Extension, Bugwood.org
