Pest Profile

Alfalfa Weevil
Hypera postica
  • Adult alfalfa weevil: Brown with a dark stripe down the back, and dark brown stripe on head with a pale line running through it. Prominent weevil snout. 3/16" long.
  • Alfalfa weevil larvae: Greenish bodies with a white stripe down the back, and black head, no legs.
  • Weevil larvae and defoliation of plants due to larval feeding damage.
  • Debarking symptoms from alfalfa weevil feeding.
  • Sizeable yield losses can occur under heavy weevil pressure.

Pest Description

The adult weevil is 3/16-inch long and light brown with a dark mid-dorsal line extending down the middle of the back. Adults possess a distinctive snout and readily fall to the ground when disturbed. Eggs are laid inside alfalfa stems in fall or spring. Small, light green, black-headed, legless larvae have a distinct white stripe down the center of the body. Larvae feed on the terminal and upper leaves of the plant early in the spring, reaching a quarter-inch in length in about three weeks. Larvae spin loosely-woven, silken cocoons, generally found on the ground among the leaf litter. Most damage occurs before the first cutting, but damage by larvae and adults can suppress yields by delaying regrowth after the first cutting.

Source of information

Pest Diagnostics

Weevil larva

Pest photo source

J.P. Michaud, KSU Entomology