Mexican Bean Beetle

Epilachna varivestis

Adult Mexican Bean Beetle Feeding Mexican bean beetles are native to Mexico, but they are present in most states east of the Rocky Moutains. They are one of the few destructive species of ladybird beetles and flock to areas where bean cultivation is widespread. Though the larvae are the most destructive life stage, the adults can rapidly defoliate host plants leading to severe crop losses.

Appearance & Preferred Hosts: Mexican bean beetles feed on many bean species including soybean, cowpea, snapbean and lima bean. They will also feed on alfalfa, clover, and kudzu. Their feeding causes the leaves to have a skeletonized appearance with most of the foliage removed. Adult beetles are oval in shape and orange to copper in color with 8 black spots on each wing cover. They are typically 0.31" long and 0.23" wide when full grown. The females lay eggs on the underside of bean leaves where they will hatch into hungry larvae. The larvae are soft, yellow, and covered with six rows of dark, branched spines. They are 0.35" long when full grown. Mexican bean beetles overwinter in the adult beetle stage.

Controlling Mexican Bean Beetles:

Remove as many overwintering locations as possible prior to the winter months (leaf litter, brush, native weeds, etc.). Destroying these spots increases exposure to adverse weather conditions, killing many overwintering adults.
Plant covers and floating row covers can restrict access to host plants, reducing crop damage and other control needs.
Early season releases of Mexican Bean Beetle parasites, ladybugs and/or green lacewings helps reduce bean beetle populations, but must be repeated yearly.
Spray plants with Surround WP to prevent Mexican bean beetles from feeding and reproducing.
Spray the soil with Beauveria bassiana in early spring to reduce the adult population.
Botanical insecticides can be used for rapid knockdown, but are most effective on larval stages. Azera Gardening combines azadirachtin and pyrethrins for a potent insecticidal punch.