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Boll Weevil

Common Name: Boll weevil

Genus: Anthonomus

Species: grandis

Identification: The adult is about 1/4-inch long with a long slender snout about half the length of the female's body.

Lifecycle: They overwinter as the adults. In the spring, they eat cavities into squares and lay single eggs in each hole. Each female can lay 100 to 300 eggs. Later, the females can lay the eggs in the boll. They hatch in 3 to 4 days, and the larvae feed inside the square or boll for 8 to 9 days. They then transform into the pupal stage inside the cavity. The adult emerges in 5 days. Although not distinct, there can be as many as 10 generations a year. When the cotton matures, the adults spread extensively and the ones that overwinter will enter diapause.

Geographic Distribution: Found in all important cotton-growing areas in the United States, including Arizona.

Damage and Treatment: Injury from adults and grubs results in the drop off or withering of squares and bolls, which means severe loss in yields. Because the various stages are spent in the squares and bolls, this insect is very difficult to control. Treatment should be made when insect populations and/or damage levels reach economic thresholds. Refer to local University Extension Pest Management Guidelines for specific state thresholds.