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Problem: Bean Leaf Beetle - Certoma trifurcata
Hosts: Beans, peas, cowpeas, soybeans, and corn
Description: Bean Leaf Beetle overwinters in the adult stage. Adult beetles are about 1/4 inch long and are a yellowish to reddish color. A black band surrounds the outer margin of the wing covers and the back normally has four black spots. Adults start feeding soon after the host plants come up where they chew small round holes in the leaves and chew on stems.
Females lay lemon-shaped, orange-colored eggs in small clusters in the soil at the base of the host plants. The larvae that hatch from these eggs are a whitish color, segmented, and have 6 small legs near the head. The ends are a dark brown. The larvae feed on roots and other underground plant parts for about 30 days. Feeding damage may be severe enough to girdle young plants. After pupation, new adults appear.
Recommendations: Row covers can provide a physical barrier to these insects. Insecticide applications are effective if plants are thoroughly covered including the underside of the leaves. Sevin (carbaryl) is effective and has no waiting period for beans.
References:
1. Kansas Garden Guide, K-State Research and Extension Pub S-51, pg 37
2. The Bean Leaf Beetle, North Carolina State University Insect Note #28
Last Update: 03/28/2003
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