Mexican bean beetle

The Mexican bean beetle is the only member of the ladybeetle family (Coccinellidae) that is a serious plant pest rather than a beneficial predator -- a useful thing to remember when you see a yellow-and-black spotted beetle on your beans and assume it is eating pests. It is the pest. The.

The Mexican bean beetle is the only member of the ladybeetle family (Coccinellidae) that is a serious plant pest rather than a beneficial predator — a useful thing to remember when you see a yellow-and-black spotted beetle on your beans and assume it is eating pests. It is the pest. The skeletonized, lacy appearance of beans after Mexican bean beetle feeding is one of the most severe forms of foliar damage in the vegetable garden.

I don't grow beans at my Long Island property, so this guide draws on Penn State Extension, Cornell Cooperative Extension, and Clemson HGIC research.

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The pest

The Mexican bean beetle (Epilachna varivestis) is in the family Coccinellidae, the same family as ladybeetles. Per Penn State Extension, adults are:

• 6–7mm diameter, oval, convex
• Yellowish-brown to copper-colored with 16 black spots arranged in three rows
• Similar in appearance to beneficial ladybeetles but copper-colored with more spots (beneficial ladybeetles are typically bright red or orange with fewer spots, most commonly 7)

The species is native to Mexico and Central America and spread through the eastern US, where it is now a common pest in most states east of the Mississippi.