Identification & Incidence: Overwintering adult weevils become active during the first warm days of spring and deposit eggs, which hatch into larvae that may defoliate the 1st cutting. Larvae pass through 4 instar stages ranging in size from 1/8 to1/2 inch and then pupate in a fibrous pupal case before transforming to adults. Life cycle includes one generation per year in Ohio.
Sampling: A larval count is made by collecting 10 stems from a location and shaking the stems in a bucket to dislodge the larvae. This is repeated until 30 stems have been sampled.
Economic threshold: Treatment is based on the stand height, tip feeding and number of larvae per stem.

Action thresholds relevant to stand height, tip feeding and density of larvae per stem.

Management Options: If sampling indicates potential for economic injury and alfalfa cannot be harvested early, rescue treatment is warranted. Parasitic wasps and fungal diseases prevent weevils from causing economic injury in most years. See chart for insecticides labeled for AW.