As a gardener, nothing is more frustrating than nurturing your vegetable garden only to have an unknown pest start chewing up your crops. If you’ve noticed damage on your green bean plants, you’re probably wondering – what is eating my beans?
Identifying the culprit pest is the first step toward protecting your plants In this article, we’ll go over the most common green bean pests, the type of damage they cause, and organic solutions to stop them in their tracks.
Common Green Bean Plant Pests
Many insects and other critters love munching on tender bean leaves and pods Here are some of the usual suspects to watch out for
Bean Leaf Beetles
These 1⁄4 inch long beetles can be yellow, green, or reddish-brown. They chew circular holes in leaves and sometimes damage pods. Look for brown larvae on the undersides of leaves.
Mexican Bean Beetles
Resembling brown ladybugs with black spots, these pests feed on bean leaves Heavy infestations can skeletonize leaves Check undersides for clusters of yellow eggs.
Japanese Beetles
Metallic green and bronze beetles around 1⁄2 inch long. They devour leaves between veins leaving lacy skeletons behind.
Leafhoppers
Tiny green wedge-shaped insects that feed on bean plant sap. They transmit disease and leave hopper burn on leaves.
Thrips
These tiny dark-colored insects rasp and feed on bean flowers and leaves. They can stunt plants and reduce yields.
Spider Mites
Not true insects, these tiny red spiders suck juices from bean leaves, causing stippling damage. Fine webbing may be visible upon close inspection.
Cutworms
Plump brown caterpillars that hide in soil and chew through seedling stems at night. They leave young plants severed at the base.
Corn Earworms
Heavy bodied green, brown, or pink striped caterpillars that chew holes in bean leaves. Sometimes damage pods as well.
Checking for Pest Damage
Regularly inspect your bean plants to spot any pest destruction early. Here’s what to look for:
- Chewed holes in leaves or disappearing leaf tissue
- Skeletonized or lacy leaves with only veins remaining
- Curled, wilted, or yellowing leaves
- White or yellow stippling on leaves
- Hopper burn on leaf edges
- Damaged flowers and developing pods
- Bean plants severed at soil line
- Frass (insect excrement) on leaves and soil
- Small insects on undersides of leaves or inside flowers
Identifying the type of damage can point toward the culprit pest. Quick action is key to save your plants!
Organic Ways to Control Bean Pests
Once you’ve detected and identified the pest infesting your bean patch, it’s time to fight back with these organic solutions:
Remove Them by Hand
For large pests like bean beetles, caterpillars, and earwigs, hand picking can help reduce their numbers. Check plants daily, wearing gloves, and drop pests into soapy water.
Use Row Covers
Floating row covers act as a physical barrier to keep flying and crawling insects from reaching your beans. Use them from seedling stage through harvest.
Attract Beneficial Insects
Ladybugs, lacewings, parasitic wasps, and praying mantises all feed on bean plant pests. Attract them with flowers and let them go to work.
Apply Insecticidal Soap
Insecticidal soaps kill soft-bodied insects like aphids, thrips, and mites on contact. Spray bean plants every 5-7 days while pests are active.
Use Neem Oil
This organic pesticide repels and disrupts the life cycle of many destructive insects. Apply it weekly as both a spray and soil drench.
Apply Bacillus thuringiensis
This natural bacteria kills leaf-chewing caterpillars when they ingest it. It’s safe for people and beneficial insects.
Use Diatomaceous Earth
The razor-sharp fossils in DE cut through insects as they move across it. Dust leaves, stems, and soil around plants. Reapply after rain.
Remove Debris & Weeds
Eliminate hiding spots for pests by clearing any plant debris around your garden. Pull weeds that can harbor insect eggs and larvae.
With persistence and a multi-pronged approach, you can protect your green beans from hungry pests and enjoy a bountiful harvest. Don’t let the bugs win!
When to Take Emergency Action
Most minor to moderate pest damage can be managed with organic methods. But if pests are destroying entire plants rapidly, stronger chemical control may become necessary.
Here are some signs it’s time for emergency action:
- Bean seeds or seedlings are disappearing from the ground
- 50% or more of the plant’s leaves are severely damaged
- Plants are stunted with excessive leaf loss or dieback
- Flowers and pods are decimated with no chance to recover
At this point, fast-acting chemical insecticides may be warranted to save the remaining crop. Always follow label directions carefully when using pesticides.
Preventing Future Pest Problems
An ounce of prevention is worth a pound of cure when it comes to protecting your green beans. Here are some tips:
- Use row covers at planting time to exclude early season pests
- Remove all previous crop debris from the garden
- Till soil in fall and spring to disrupt overwintering pests
- Rotate bean plantings to different areas from year to year
- Clean up fallen leaves/debris where earwigs hide
- Avoid excess nitrogen fertilizer to limit aphids
- Irrigate in morning so plant foliage dries by night
- Check traps and plants daily for signs of new damage
With proactive measures, close monitoring, and timely intervention, you can enjoy a bountiful bean harvest free of chewed leaves and scarred pods. Don’t surrender your veggies to the bugs!
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Life cycle of bean leaf beetles Bean leaf beetle feeding on a bean leaf
- Adult bean leaf beetles spend the winter in the ground under leaves (mostly in wooded areas), in grass clumps, or inside curled, dried leaves in leaf litter.
- They emerge from mid‑May to early June. They feed, then mate.
- They lay groups of about 12 orange eggs in the ground around the base of the beans.
- These bugs eat more than just snap beans (also known as green beans or string beans). They eat soybeans, clover, dry edible beans, vetch, alfalfa, and a few other weeds that are related.
- Depending on the temperature, eggs hatch into larvae after one to three weeks.
- Larvae that are white eat the roots of bean plants and only do minor damage to plants.
- For about two to three weeks, larvae eat food and then change into pupae in the soil.
- There is usually only one generation per year in Minnesota. Two generations can happen in the southern part of the state. The first generation shows up in July, and the second generation shows up in late August and early September.
- A lot of bean leaf beetles can be found in places with mild winters or enough snow cover to keep the adults warm and safe during the winter.
Damage caused by bean leaf beetles
- Bean leaf beetles like to eat soft, young plant tissue as adults.
- Large groups of adults can eat the first true leaves and kill young seedlings.
- Extensive feeding can weaken the plant and reduce the yield.
- Later in the season, when pods start to form, adults will also eat the outside of them. This feeding only affects the appearance of the pods.
- Bean leaf beetles are known to carry and spread germs between plants. The good news is that this doesn’t affect vegetable growers because these diseases don’t affect snap bean varieties.