22 Common Bean Pests and How to Eliminate Them (2024)

It’s inevitable that if you’re growing beans, you’ll catch the attention of predators that think these legumes are being grown just for them. Now, some only affect certain species, while others will annihilate whatever legume they come across.

Read on to learn about 21 of the most common bean pests you’ll have to deal with while growing tasty beans on your homestead and how to deal with them.

Don’t let the number of bean pests dissuade you from trying to cultivate them in your own garden! Just because these may potentially show up doesn’t mean they will: you can go years without encountering any pests.

Simply knowing what you may encounter (as well as how to deal with them) can alleviate a lot of stress when and if any of these pests do show up.

1. Aphids

These bean pests are just ridiculous, aren’t they? They manage to wreak havoc on so many different species, and no bean cultivars are exempt from their attention.

You can blast them off your plants with a hose, spray them with neem oil, or douse them with diatomaceous earth (DE) to get rid of them. In fact, the honeydew they release can actually act as an effective glue to keep the DE around!

Additionally, try releasing ladybugs into your garden if they don’t already congregate there.

2. Bean Beetles

Bean leaf beetles (Cerotoma trifurcata) look a bit like ladybugs, but are often yellow, white, or beige, instead of red or orange. Mexican bean beetles (Epilachna varivestis) are usually pale orange, and have a slightly fuzzy appearance.

Both of these beasties can defoliate your bean plants before you can blink, and may damage the flowers and pods as well.

Rosemary, summer savory, catnip, and nasturtiums are all great companion plants for your crop, as they help to repel these unwanted bean pests. Diatomaceous earth works too, and plants that attract lacewings (i.e. most Asteraceae species) can encourage those insects to feast upon the interlopers.

Lacewings love plants in the aster family, parsley family, herbs, and native flowers.

As far as manual controls go, row covers can keep your plants safe from beetles, and be sure to inspect them daily for yellow eggs or fuzzy larvae beneath the leaves. Pick these off and destroy them when and if you find them.

3. Bean Pod Borer

Also known as a “mung moth,” this insect (Maruca vitrata) is the number one obliterator of legume crops in Africa , Asia, Central America, and the Caribbean. Its larvae are so voracious that they can destroy upwards of 80% of a crop at a time!

Although some pesticides have proven effective against it, the best defense against this insect is to attract parasitic braconid wasps. These insects lay their eggs on pod borer larvae, so their young kill these caterpillars before they can continue their life cycle.

Attract braconids by planting Apiaceae plants such as Queen Anne’s lace, dill, and fennel, as well as thyme, catnip, buckwheat, feverfew, yarrow, and chamomile.

4. Slugs and Snails

We’re putting these under the same header because whether these gastropods have a shell or not, they do the same type of damage, and the means of fending them off is identical.

Check your plants with a flashlight at dawn and dusk. If you see any of these creatures, pick them off and drown them in soapy water or feed them to your poultry.

Alternatively, you can set up a tasty beer trap to entice these bean pests away from your plants, or a trap crop of favorites like hostas 20 to 30 feet away from your main crop.

Learn more tips in our guide.

5. Bean Weevils

Have you ever cooked some dry beans only to find a ridiculous amount of dead weevils floating in the water? These are the larvae of bean weevils (subfamily Bruchinae), and they’re atrocious.

Adult weevils lay their eggs on ripening bean pods, and the larvae wriggle their way into the pods and make themselves at home.

You’ll recognize their presence by the telltale dark dots on your beans that indicate that they’ve burrowed in. These are more difficult to spot on dark beans but are glaringly obvious on lighter-hued ones.

Controlling them involves storing your beans in pest-proof containers. Keep food storage areas clean and try to reduce moisture in your food storage. You can do this by using a dehumidifier or improving air circulation.

6. Thrips

If your bean plants look as though their leaves have been bleached, then you’re likely dealing with thrips. These skinny beasts lay their eggs inside leaf tissue, and then their teensy larvae emerge to eat their way through the foliage, flowers, and pods.

Neem oil is very effective at getting rid of them, as is diligent pruning. If you see any leaves that seem to be affected, use clean snips to remove affected foliage and burn it. Since thrips are so tiny (around 2mm), you may be able to kill most of them with quick, early intervention.

7. Leaf Miners

These jerks annihilated my scarlet runner beans a couple of years ago, much to my dismay. You’ll know you have leaf miners if you see pale, squiggly lines all over your bean plants’ leaves, as the insects literally “mine” their way through the leaves’ soft tissues, between veins.

Spinosad and neem are both effective against miners, as are Diglyphus isaea predatory wasps. Since miners are the larvae of various flies, you can also protect your beans by using floating row covers.

If you’ve dealt with miners in the past, be sure to deep-till your soil in the autumn to reveal the eggs and larvae for birds to dispatch.

8. Stinkbugs

Stink bugs like the brown marmorated stink bug (Halyomorpha halys) and the green stink bug (Chinavia hilaris) have shield-shaped bodies, and they do indeed stink if you smash them. They feed on plants, including the fruits, leaves, and stems.

Their feeding causes wart-like growths or dents on the bean pods.

Learn about controlling them in our guide.

9. Spider Mites

Although spider mites aren’t specifically bean pests, they can certainly affect your bean plants if they’re already present in your garden. If your plants’ leaves have little holes on them, and there’s gossamer webbing anywhere in the vicinity, you’ve got mites.

Since spider mites like dry conditions, you can make the plants less palatable by misting them with your hose regularly. Add some neem oil to the spray to make the leaves particularly unpleasant, and the mites will head elsewhere.

10. Armyworms

These bean pests aren’t worms at all but are rather the larvae of certain night-flying moth species. You’ll often find them hiding in your lawn, but they’ll crawl out during the night to feast on your plants.

If you find any brown-headed larvae with yellow, brown, or green stripes down their bodies, you’ve got armyworms to contend with.

Deal with these by encouraging braconid wasps, picking them off and drowning them if you find them, or by using species-specific natural pesticide such as Bacillus thuringiensis.

11. Cutworms

If your bean plants are dying off because something has been cutting them down at ground level, then cutworms are the likely culprits. These bean pests are the soft-bodied larvae of certain moth species that lay their eggs on the soil’s surface.

When the eggs hatch, the larvae squiggle over the soil and gnaw their way through whatever greenery is in their path, i.e. your bean plants’ stems.

Collars are ideal for stopping them, as they both create barriers to the cutworms’ eating habits. Similarly, a thick layer of diatomaceous earth will shred and dehydrate them if and when they cross it.

12. Caterpillars

The caterpillars you’ll find on your bean plants may be the larvae of several different moth and butterfly species. As beautiful as they may become after their pupal stage, they’ll wreak absolute havoc on your plants before they get to that point.

They love leafy greens, and a large group of caterpillars can defoliate your bean plants in a matter of days.

Pick them off your plants at dawn and dusk, treat them with neem or Bacillus thuringiensis, let your poultry into the garden to eat them, and do your best to attract braconid wasps to obliterate them.

13. Loopers

If you’re growing soybeans, then some of the main bean pests you may have to contend with are bean loopers. These dark green inchworms are the larvae of Chrysodeixis includens: the soybean looper moth.

Once mature, they’re brownish-gray and are almost bark-like in appearance.

Loopers are difficult to deal with because they’re often resistant to pesticides—both natural and chemical. Additionally, they defoliate from the bottom of the plant upwards, so their damage isn’t immediately apparent.

The good news is that they show up late in the season and prefer old leaves to new ones.

Furthermore, soybeans can withstand a lot of defoliation and still produce a decent harvest.As such, try to pick them off when possible, and let your poultry at them. Even if they eat holes through most of your plants, said plants should still survive and thrive.

14. Root Maggots

These bean pests in the Anthomyiidae family are the larvae of certain fly species that lay their eggs in the top soil layers. Their larvae burrow down into the soil, where they crawl into your beans’ roots and eat the delicate tissues around them.

The flies that lay these eggs like wet, heavy soil, so ensuring that your soil is well-draining is one way to fend them off. Additionally, you can use floating row covers to keep them from landing nearby.

Keeping debris off the soil surface and raking around there to loosen eggs and larvae for birds to feed on is another good preventive measure.

As far as chemical controls go, pyrethrin and spinosad are effective against these larvae, but do your research on safe usage protocols so you know how to treat produce that may have come into contact with them.

15. Root-Knot Nematodes

If your bean plants are turning yellow and wilting over, with no sign of insect activity or fungal infections in their aerial parts, you’re possibly dealing with root-knot nematodes (Meloidogyne spp.).

These microscopic pests burrow into your plants’ roots and destroy them from the inside.

In addition to yellow leaves, it might cause wilting. If you dig the plant up, you’ll find knotted, lumpy roots. You can squeeze these growths and rotten ooze will come out. These knots limit the plant’s ability to take up water, effectively killing them. There’s no cure.

Root knot nematodes are extremely difficult to eliminate. The most reliable way is to plant crops they can’t feed on. Since they aren’t very mobile and can’t move to better pasutres, they’ll die.

You can also treat the soil with a nematicide that contains Quillaja saponaria.

In cases like this, prevention is better than treatment after the fact. Ensure proper crop rotation annually, and treat your soil in the autumn in preparation for springtime bean planting. Turn the soil over to a foot deep, and then plant nematode-resistant varieties.

Look for “VFN” on the label. This indicates the plant has some resistance. You should also plant lots of marigolds nearby or in-between years, as these have been proven to kill nematodes.

16. Soybean Cyst Nematodes

Although these bean pests primarily attack soybeans, they have been known to damage other bean plants on occasion as well. These tiny segmented worms (Heterodera glycines) burrow into your plants’ roots, causing them to wilt from being unable to uptake nutrients or water effectively.

If you find that your plants are affected by them, pull the plants up and destroy them. Till the ground down a foot deep and solarize the soil, then rotate your crops and don’t plant any beans there for five years.

When you do, aim to plant nematode-resistant varieties so they’ll be less vulnerable to infestation.

17. Deer

We may love deer from afar, but that doesn’t mean that we want them in the garden. They’ll happily devour whatever plants they can get to, and they seem particularly fond of bean and pea greens.

While many people use alliums such as garlic chives to repel deer, this isn’t an option with beans. Alliums are bad neighbors for legumes, as they release chemicals into the soil that destroy beneficial bacteria on these plants’ roots.

This prevents them from either absorbing nitrogen (which is necessary for their own growth) or fixing it into the surrounding soil to benefit adjacent plants.

Learn some foolproof tips for keeping deer out of the garden in our guide.

18. Rabbits

The best way to keep these adorable critters away from your bean plants is with a fence. Use chicken wire to cordon off the area, with at least one foot beneath the soil and curling outwards so they can’t burrow under it and three to four feet of height above it.

You can also lure them away from your beans with a trap crop that you don’t really care about. Sow older bean seeds, lettuce, spinach, and parsley in a little patch away from your main garden and that should keep them occupied.

Additionally, cut down tall stands of grass, and keep a space of 15-20 feet clear around your garden: since rabbits are afraid of crossing wide open spaces, they’ll be less likely to beeline for your beans.

19. Opossums

Opossums are opportunistic feeders and will munch on whatever’s in easy reach. As such, if you live in opossum country and your plants’ pods are low to the ground, expect some losses. Fortunately, these animals are unlikely to do much damage and are quite easy to deal with.

They’re skittish, so having motion-activated lights on the property will scare them off. Additionally, you can lure them away from your plants by offering them tasty snacks like carrots, apples, berries, and nuts.

Remember that opossums eat thousands of ticks and are immune to rabies, so please be kind to them: they’re valuable members of the ecosystem, and actually very kind, gentle creatures.

20. Groundhogs, Woodchucks, Marmots, Rodents

No matter what you call these critters, they’re likely to snack on your beans if they get the chance to do so. Like rabbits, you can scare them off with predator feces or urine, though stubborn ones will still prowl around now and then.

Your best bet is to fence off your beans so they can’t get to them, and offer something easy like a strawberry patch as a trap crop for them instead.

Once again, rodents aren’t “bean pests” specifically, but will certainly eat your plants if they’re within easy reach. Fencing off your beans with chicken wire is effective against squirrels and other larger rodents, but mice may still be able to get through.

As such, you’ll need some other preventive measures.

For example, keep grasses and other wild plants cut very short, as this will deny them hiding places: they don’t like to run out in the open much, so they’ll avoid cutting across open lawns.

Additionally, you have outdoor cats, let them hunt to keep the rodent population down. Just don’t use poison to reduce their numbers: owls, hawks, and other predators may take poisoned mice back to the nest and accidentally kill their own young.

21. Outdoor Pets

Believe it or not, some dogs and cats absolutely love to snack on beans. This doesn’t make them bean pests per se, but they’re definitely opportunistic bean bandits.

If you can’t keep your pets indoors, then fence off your beans so they can’t get to them. Since pets can also carry pests like mites or fungal pathogens from one section of your property to another, fencing off your edible plants can keep them safe from cross-contamination.