Home

Diseases of  Alfalfa  Corn  Soybeans  Wheat

Insect Pests of  Alfalfa  Corn  Soybeans  Wheat

Weeds  Identify  Monocots  Dicots  Grasses  Sedges  Lilies  Broadleaf

Scout Info
Kentucky IPM Pest Information Pages

Alfalfa Weevil: Kentucky Alfalfa IPM

Alfalfa Weevil


Description

Adult alfalfa weevils are 1/8 to 1/4 inch long, grayish brown to black beetles with a broad dark stripe down the center of the back. The front of the head extends downward in a distinct snout. Groups of eggs are laid in live and dead alfalfa stems during the fall and spring. The newly-hatched legless, grub-like larvae are pale yellow. They soon become green with a white stripe down the middle of the back. After feeding for about 4 weeks, the full grown larvae spin a net-like spherical cocoon near the top of the plant and pupate. The adults emerge within 10 days. After a short feeding period, they leave the field and spend the hot summer months hidden and inactive. The adults fly back to alfalfa in the fall and remain there over the winter.

Alfalfa weevil life stages

Damage

Alfalfa weevil damage

Alfalfa weevil larvae are the most important pest of the first cutting. They feed at the tip of the stem leaving many small rounded holes. Eventually, all of the leaves at the top of the plant may be destroyed. Heavily infested fields take on a bleached out appearance, as seen in the yellow untreated strips in the picture. In addition to reducing yield and quality of the first cutting, the second cutting may be stunted. Larval and adult feeding on the regrowth may set back recovery and development after the first harvest.

Alfalfa Weevil Adult Activity

Adult alfalfa weevil activity

Larval Activity

Larval alfalfa weevil activity

IPM Techniques and Scouting Procedures

References and Additional Information


This site was created and is maintained by Pat Dillon, Department of Entomology, University of Kentucky, S-225 Agricultural Science Ctr North, Lexington, KY USA  40546-0091 (phone: 859/257-3571). Please send questions or suggestions to: pdillon@uky.edu