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Bean Leaf Beetle

Closer Look Of The Bean Leaf BeetleCalled the bean leaf beetle, this quarter inch long insect is considered one of the worst enemies of soybeans and other legumes, young plants being especially susceptible. They normally eat the tender leaves but will attack the pea-pods if leaves become tough or dry. Adults can transmit several viruses, the bean pod mottle virus being the worst. Although bean beetles can be found as far north as Canada, they are more of a problem in southern states. There are normally two generations of beetles, one in spring and the other in summer. Once rare, the bean beetle is now becoming more of a problem throughout the country. Be advised that this beetle is many times mistaken for the common Lady Bug, which is a beneficial insect, so BE CAREFULL when attempting to identify it.


Adult Bean Leaf BeetlesBean beetles come in various colors, such as yellow, orange, red, grey or tan, but all have a black triangle at the base of their forewings, and most have four black spots on their backs. The adults contain chewing mouth parts and attack the green leaves of the plant, producing small round holes. Normally found on the underside of leaves, the adult will fall to the ground when disturbed. They over-winter in fields near fields of legumes.


Bean Leaf Beetle EggsWhen temperatures reach about 50 degrees F, adult females lay upwards of 200 eggs in clusters of 12 to 20 eggs, each about 1/32” long. Eggs are spindle or lemon shaped, are orange or reddish in color, and are laid in the soil near the base of the host plant. They hatch in about a week or two and begin to attack the roots of the plant.


Bean Leaf Beetle LarvaeThe larvae of bean beetles are white in color and cylindrical in nature and are black or dark brown at both ends and have six small legs near the head. They move underground and attack the legume crops from below and feed for between three to six weeks. They can attack the roots, root hairs and stems, but seem to prefer root nodules.


Bean Leaf Beetle PupaAfter the larvae have finished their life cycle they form an earthen cell and pupate for about a week before emerging as new adults to begin laying eggs for the next generation.

Vegetables That Bean Leaf Beetles Like To Eat

Beans Corn Peas


Unfortunately, bean beetles are very difficult to control without chemicals. In home gardens, use 1/2 tablespoon of Sevin per gallon of water and treat the plants several times early in the season, especially spraying the underside of the lower leaves. Also, rotenone is effective as is pyrethrin and neem. Remember to use these chemicals at dusk when the bees have returned to their hives, and only if absolutely necessary.

Floating Row Cover Over The Cabbage PlantsUse of floating row covers will protect susceptible plants in small home gardens.

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