Mexican Bean Beetle

Epilachna varivestis — the Mexican bean beetle — is one of the most economically destructive pests of bean crops in the US and one of the few plant-feeding species in the otherwise predator-dominated ladybeetle family Coccinellidae. Most Coccinellidae are voracious aphid predators (and important beneficial insects), but the subfamily Epilachninae contains plant-feeding species that have evolved to consume leaves and developing fruits. Adult Mexican bean beetles are 6-8 mm long, oval, and yellow-orange with 8 black spots on each elytron — superficially resembling the beneficial multicolored Asian lady beetle and other true ladybeetles. The species is native to southern Mexico and Central America and reached the southern US in the early 1900s. Adults and larvae feed on the underside of bean leaves, scraping off the soft tissue between leaf veins and leaving the characteristic 'skeletonized' lace pattern. Heavily infested fields can be defoliated within 1-2 weeks. Major host crops include snap bean, lima bean, kidney bean, mung bean, soybean, and cowpea. The species is a continuing concern for organic bean farmers and home vegetable gardeners across the eastern, central, and southern US, and is the basis of the federal Mexican Bean Beetle Biocontrol Program (using introduced parasitoid wasps from the species' Mexican home range as biological control agents).