Pea Leaf Weevil

Description

Adult: Adults are 4.5 mm long, slender, gray-brown and have a broad snout.
Egg: Eggs are white when laid but gradually turning black before hatching.
Larva: White with a dark brown head capsule. Legless and curls in a “C” shape when disturbed. Ranges from 3mm-6mm in length. 

Life History

Adult pea leaf weevils overwinter in alfalfa and other perennial legumes. Adults emerge in spring and feed on host crops (alfalfa, beans, peas, and other legumes). After mating, females lay thousands of eggs singly near the soil surface of host plants. After two to three weeks, the newly hatched larvae burrow into the soil and feed on the nitrogen-fixing root nodules of the host legumes. They develop through five instars in four to eight weeks. The mature larvae pupate in the soil before the new generation of adults emerge in midsummer.

Damage

Adults feed on new foliage, causing notched shapes along the margins. This feeding typically doesn’t result in yield loss. The larvae feeding on nitrogen-fixing root nodules can reduce soil nitrogen which may affect current and future crop yields.

Management

Cultural

• Scout crops. Begin scouting when legume crops are nearly emerged and look for the leaf-notch feeding damage on the lower foliage.
• Plant later in spring. Avoid feeding damage from the early peak emergence and dispersal of first generation adults.
• Plant trap crops. Early spring-planted faba beans or winter peas have been used as a trap crop to deter pea leaf weevils from the cash crop.

Chemical

If populations reach an economically damaging threshold, consider foliar insecticide sprays. These should be applied before the adult females lay eggs.