How to Identify Mexican Bean Beetles

If something has been eating your garden green beans, it's likely the Mexican bean beetle. This common garden pest can destroy an otherwise healthy green bean garden in very little time. Learn to identify Mexican bean beetles so you can control these destructive pests.

Difficulty: Moderate

Instructions

Things You'll Need:

• Insect field guide
• Magnifying glass

1. Observe the green bean plant damage. Look for holes in the leaves. Eventually, these holes will become more frequent until the leaf is a skeleton of its previous state. Mexican bean beetles also eat the green beans. See if there are small tears and bite marks in several different spots on the green bean.

2. Spot a ladybug look alike. Mexican bean beetles are similar to ladybugs in size and structure. The beetles are tan with about twenty-four spots on their backs. They feed during the evening or early morning and crawl down to the soil or undersides of the leaves for protection from the hot sun during the day.

3. Check under the leaves. Mexican bean beetles lay their eggs on the undersides of the bean plants. Look for small clusters of about forty yellow eggs. The beetles can lay several generations in one season. Keep checking throughout the garden season for more egg clusters.

4. Use an insect field guide and find a picture of the Mexican bean beetle to help identify the pests. Check local agricultural centers or greenhouses for books on common garden pests. Likely, the Mexican bean beetle is in one of those guides.

5. Hire an expert to identify the Mexican bean beetles. If you're not sure if the insect you have is a Mexican bean beetle, an entomologist (insect scientist) or even a horticulturist may be able to positively identify it. Place the insect in a small baggie and take it along with you to a local greenhouse where you are likely to find a horticulturist.

Tips & Warnings

• Use a magnifying glass to help you get a closer look at the green bean plants.