Alfalfa hay-Pea leaf weevil

Sitona lineata

Pest description and crop damage Adults are grayish brown weevils about 0.16 inch long with three faint stripes on the thorax. They appear in large numbers in spring and sometimes late summer.

Adult feeding occasionally can cause substantial defoliation, which is of most concern on seedling stands. Pea leaf weevil adults migrate in large numbers when other crops they are infesting are harvested. Their presence in fields is usually spotty, and targeted treatments at field margins can be very effective.

Management-chemical control

No materials are currently registered for pea leaf weevil in alfalfa hay. However, carbaryl and all pyrethroids applied to control other pests will control pea leaf weevil.

  • chlorantraniliprole/lambda-cyhalothrin (Besiege) at 0.059 to 0.088 lb ai/a. PHI 1 day for forage and 7 days for hay. REI 24 hr. Minimum of 5 days between applications. Do not exceed 0.12 lb ai of products containing lambda-cyhalothrin or 0.2 lb ai of chlorantraniliprole-containing foliar products per acre per growing season. (Group 28 and 3A)