Bean Pests

By National Gardening Association Editors

There are a variety of insects that attack bean family crops. Here are some of the most common culprits.

Mexican Bean Beetle

The Mexican bean beetle is the worst bean pest. The beetles usually first appear before the beans blossom. They feed for a week and lay yellowish orange egg masses on the undersides of the leaves. The average female lays more than 400 eggs. If you see any beetles, pick them off and destroy the egg clusters right away. Beetles in advanced stages of growth can be controlled with applications of pesticides such as pyrethrum. Also, spade or till the plants into the ground as soon as the harvest is over. It will improve the soil, and the beetles won't have anything to eat, so they'll leave.

If you don't like using chemicals on your plants and still want to deter pests, you can try companion planting: marigolds, onions and garlic grown near bean plants sometimes keep the bugs away. Other gardeners buy and release Pedio wasps (Pediobius faveolatus) or spined soldier bugs, beneficial insects that parasitize bean beetle larvae.

Other Bean Pests

Another pest is the bean leaf beetle, which eats large holes in bean leaves, feeding from the underside.

The cowpea curculio is a very destructive pest in the South. It eats holes in pods, beans and southern peas.

Root-knot nematodes may also be a problem, particularly in the South and West. These very small, eel-like creatures live on the roots and damage many crops. A bad infestation of nematodes will leave your plants quite stunted.

Bean weevils may attack dry beans in storage. You can avoid the problem by heating the beans (130 to 140F) or chilling them (35° to 40° F) for half an hour and storing them in tightly covered containers.

Contact your Extension agent for advice of controlling all of these pests.

Minor Pest Problems

Other insects such as aphids, spider mites, Japanese beetles, stinkbugs, leafhoppers, lima bean pod borers and leaf miners may be problems for some gardeners in different parts of the country. Many of these pests can be controlled by spraying pesticides such as pyrethrum. For the most effective time to spray, check with your County Extension agent.

The steps for crop protection are the same with all these pests: early detection, correct identification of the pest and careful implementation of the recommended procedures for control.

Sources of Information

The best source for help and advice is the nearest Cooperative Extension Service office or county agent. Many offices publish local guides that help you identify the various pests in your region and inform you of possible controls. Remember to follow all directions carefully if you use sprays or dusts in your garden.

Other articles in this series:
1. Preserving Beans
2. Watering & Fertilizing Beans
3. Caring For & Harvesting Beans
4. Bean Diseases
5. Bean Pests ← you're on this article right now

This article is a part of our Vegetable Gardening Guide for Beans and Asparagus / Care.

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