Mexican Bean Beetle
Pest · Commonly affects: Snap beans, Lima beans, Cowpeas (black-eyed peas), Soybeans, Dry beans (kidney, pinto)
The Mexican bean beetle (Epilachna varivestis) is a leaf-feeding member of the lady beetle family and one of the few relatives in that group that harms crops instead of helping the garden. It is among the most destructive pests of beans in the eastern and central United States, and heavy populations can defoliate plants before harvest.
How to identify it
Adults are oval and strongly domed, about a quarter inch long, and colored yellow to coppery orange with sixteen black spots arranged in three rows across the back, so they look like an oversized tan ladybug. The larvae are the more telling sign: bright yellow, soft, oval grubs covered in rows of branched, dark-tipped spines that feed in groups on the leaf undersides. Also watch for clusters of upright yellow-orange eggs stuck to the underside of the leaves.
Damage
Both the adults and the spiny larvae feed on the lower surface of the leaves, scraping away the tissue between the veins and leaving a lacy, skeletonized look that browns as the leaf dries. Severe feeding can strip the foliage, stunt the plants, and cut pod set, and the beetles will also gnaw on pods and stems once the leaves run short.
Prevention
Rotate beans to a different part of the garden each year and avoid planting next to last season's bean patch, since the adults overwinter in nearby leaf litter and along field edges. Clean up and remove or compost spent bean plants promptly after harvest to reduce overwintering shelter, and give plants good spacing and healthy soil so vigorous growth can better shrug off some feeding. Choosing early-maturing varieties and planting early can help a crop stay ahead of the beetle's larger later-summer generations.
How to manage it
Scout the leaf undersides often and handpick adults and larvae into a container of soapy water, crushing the yellow egg clusters whenever you spot them, which works well in a home-sized planting. Cover young plants with floating row covers, which beans tolerate because they self-pollinate, to keep egg-laying adults off the foliage. Encourage natural enemies such as the spined soldier bug and the small parasitic wasp Pediobius foveolatus that attacks the larvae, and pull and destroy heavily infested plants at season's end rather than leaving them as a breeding source.
General guidance for US home gardens, focused on prevention and non-chemical control. For a confirmed diagnosis and options specific to your area, contact your local Cooperative Extension office. Page updated Aug 4, 2026.