Both adults and grubs can cause massive damage to all varieties of plants. Beetles are red to yellow with a black band around their outer edge. They also have black spots on their back. Plants with beetle damage have holes chewed in the leaves, and may turn yellow and wilt depending on the extent of the damage. Female beetles lay eggs at the base of plants in the soil.
Eggs are reddish orange.
When grubs hatch from the eggs they feed on the plant below the soil at the roots, which can kill the plants. Adult beetles feed on the undersides of the leaves and blossoms. Each year, up to 3 successive generations can cause damage if left untreated as new eggs are hatched and the feeding and breeding cycle begins anew. Apply a carbaryl or diazinon containing insecticide when you first note damage in your bean plants. Make sure you coat the undersides of the leaves where adult feeding occurs.