Insects Destroying Bean Plants

Our green beans are being rampaged by bugs. They are grayish-brown with black dots and remind me of lady bugs. How can we control these hungry pests?

Several insects resembling your description can cause this type of damage. The bean leaf beetle is ¼ inch long, yellow-green to red with four black dots on its back. They eat small holes in the leaves and may even feed on the pods. High populations can devastate a planting. Cover plantings with floating row covers to keep the insects off. Firmly secure the edges to prevent the beetles from crawling underneath.

The Mexican bean beetle is a bit larger and can be yellow or coppery brown with 16 black spots. The immature stage, larvae, is orange or yellow, fuzzy and rather hump-backed. Both the adult and larvae eat holes in the leaves giving it a lacy appearance. Remove and destroy any of the insects and their bright yellow eggs that you can find.

A thorough clean up in the fall will reduce problems with the bean leaf and Mexican bean beetle in next year’s garden.

The spotted cucumber beetle is more elongated, yellow-green and has 12 spots on its back. This beetle eats larger holes in the leaves. Large populations causing high levels of damage can be controlled with insecticides. Consider using more eco-friendly products such as Neem. Make insecticides your last resort as songbirds, toads, and several beneficial insects that eat these pests may be injured or killed by some pesticides.

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