Boll Weevil

Anthonomus grandis — the boll weevil — is one of the most economically and culturally consequential insect species in US history. Native to Central America and Mexico, the species crossed the Rio Grande from Mexico into south Texas around 1892 and immediately began devastating cotton crops. The boll weevil's biology is precisely matched to the cotton plant: female weevils bore into developing cotton bolls (the seed pods that contain the lint fiber), lay eggs inside, and the larvae develop within the boll, destroying the developing cotton. A single female can lay 100-300 eggs across her 1-2 month adult lifespan; in heavily infested fields, virtually every boll on every plant is destroyed. The species spread northward and eastward across the US cotton belt at approximately 60 km/year, reaching the Atlantic by 1922. Cumulative US damage from 1892 through eradication is estimated at $22 billion (in 2010 dollars). The boll weevil reshaped the US South socially and economically: the destruction of cotton accelerated the Great Migration of African Americans from the rural South to northern cities, broke the agricultural dominance of cotton in many counties, and forced diversification into peanuts, soybeans, and other crops. The town of Enterprise, Alabama famously erected a statue of the boll weevil in 1919 ('In profound appreciation of the Boll Weevil and what it has done as the herald of prosperity') to commemorate the forced diversification that ultimately enriched the area. The federal Boll Weevil Eradication Program launched in 1978 used pheromone trapping (the male-produced aggregation pheromone grandlure), targeted insecticide applications, and crop sanitation; by 2010 the species was successfully eliminated from essentially the entire US cotton belt. Eradication is one of the most successful single-species pest elimination programs in agricultural history. Boll weevils still occur in Mexico and South America.