So, you need to get rid of the bean beetles eating up your legumes, green beans, or pea plants.
These little buggers are driving you up the wall.
And every day you wake up to your leaves being chewed up- left with silver spots, holes, and skeletonized foliage.
How do you save your bean plants from the beetles?
In this article, you’ll learn about:
- Why you have bean beetles
- What they’re eating
- Where they’re hiding
- Where they’re coming from
- The bean beetle life cycle
- How to get rid of them naturally
- Ways to keep bean bugs off your plants permanently
- And more
By the end of this guide, you’ll have a solid foundation of knowledge to control, manage, and eradicate bean beetles from your plants.
It’s quite detailed because it covers everything you need to know (or nearly).
So bookmark this page for easy reference later- you’ll probably be coming back a few times during the process.
And as always, feel free to post your questions at the end of the page if you’re confused or have a special circumstance.
Or contact me directly and I’ll try to help you out ASAP (I get a lot of emails so please be patient!).
Sound good? Let’s send those beetles back to the wild.
Disclaimer: As an Amazon Associate I earn from qualifying purchases. This specific article contains affiliate links to relevant products, which means I may receive a small commission if you complete a purchase. This does not affect/bias the content in any way, nor does it cost you a cent more than what you’d normally pay for helpful products. Please read the Terms of Service for further information. Thanks for supporting the site.
What’s a bean beetle?
The bean beetle is a common garden and farm pest that’s known for its extensive damage of string beans (snap peas/green beans), and other related legumes or beans like cowpeas, pinto beans, black beans, clovers, kidney beans, and more.
This little bug has two distinct parts of its lifecycle- a yellow spiked caterpillar and an adult beetle that looks like a ladybug.
Although small infestations are controllable, larger ones will absolutely decimate your plants. Younger plants are vulnerable to bean beetles and can be killed within days.
And these beetles tend to target the younger plants because of their tender, softer foliage.
There are over 400,000 beetle species on earth.
So it’s easy to get this beetle confused with the rest, especially to the casual gardener.
Thus, many common nicknames exist for bean beetles.
Here are some of their aliases:
- Southern cowpea weevil (mistakenly)
- Bean beetle
- Bean leaf beetle
- Bean bug
- Mexican bean beetle
- Mexican beetle
- Bean weevil
- Leaf beetle
- Epilachna varivestis
- Callosobruchus maculatus
- Cowpea beetle
- Bean ladybug (mistakenly)
- False ladybug
Where do bean beetles live?
Mexican bean beetles feed on the leaves, stems, and sometimes directly on the bean pod.
If you don’t take care of them, you can expect to have no bean harvest this season.
Formulate a plan to get rid of them quickly and naturally. This guide can help you.
Appearance – What does a bean beetle look like?
Bean beetles are easy to identify from their patterns.
The beetles and the larvae are completely different in appearance and it’s useful to identify both so you can tell if it’s a bean beetle or some other type of similar beetle (like larder beetles, potato beetles, and cucumber beetles)
The bean beetles are small and are about 0.25” in length at adult size. The most noticeable characteristic about them is the spots on their back.
They have a total of 16 spots, which you can use to identify the adult pests. Their color varies as they age and the species itself.
You’ll see everything from tan to orange to yellow which slowly changes the older they get.
The adults almost look like ladybugs.
You can quickly get confused over the two species if you don’t look closely. Remember that ladybugs can be both red and orange, which are the same as bean beetles.
So it’s easy to get them mixed up. The adults do the most damage as they feed in their active period in May to June and July to September.
The larvae are small and about 0.5” in length. They’re yellow and have spiny protrusions from the body. The spines will have marked tips that slowly turn dark over time.
They may look like those black hairy caterpillars you see with a ton of pokey spikes all over the body.
With an ovular body shape and covered with sharp needles, predators will want to think twice about the eating one.
Ladybug vs. bean beetles
Since these two bugs are so similar, I thought I’d add this extra section for people to more easily identify between the two.
- For starters, ladybugs are beneficial insects that can help get rid of bean beetles. Bean beetles are NOT beneficial and will destroy your crops.
- Both the adult beetles and ladybugs are very similar to the spots on their back and elytra shaped in a dome.
- Mexican bean beetles are orange to yellow to copper with 8 spots per wing. Ladybugs are red, orange, or brown. Some are tan or silver.
- Ladybugs can have no spots or only 15 spots.
- Mexican bean beetles always have 16 spots with 8 on each wing cover.
The wings are the easiest way to tell the difference.
- Count the number of spots on the wing cover (elytra).
- If you count a total of 16 spots, it’s a bean beetle. If you see no spots or 15 spots, it’s a ladybug.
- Check a single wing cover and look for 8 spots. Then check the other.
- If it’s an identical wing, then it’s a Mexican bean beetle.
- If it’s missing a spot or has less than 8, then it’s a ladybug.
- Ladybugs won’t damage your plant leaves, while Mexican bean beetles will chew holes nonstop.
- Ladybugs don’t have a caterpillar, wormy part of their lifecycle, while bean beetles have yellow larvae with black-tipped spikes.
Why are bean beetles important?
Bean beetles can help distribute plant seeds and propagate them.
They’re a common bottom feeder in garden ecosystems that parasitic wasps feed on and use their larvae as prey.
So in other words, bean beetles are an imperative part of the food web (food chain) that other insects benefit from by eating their larvae to sustain themselves in the overall ecosystem- sounds pretty cool, eh?
The life cycle of bean beetles is straightforward and similar to any other beetle species.
The larvae go through multiple molts and get successively larger each molt.
They eat and eat until they’re ready to pupate. After pupating, they emerge as adults, which feed on plant matter until the winter.
They’ll overwinter on plant leaves or under the soil to shield themselves against the elements.
After the springtime comes around, they’ll come out, mate, and lay eggs on your beans. The cycle then starts all over again.
Most bean beetles only have a single generation per annum, so it’s relatively easy to get rid of them. But higher temperatures or food availability may lead to multiple generations.
Some species will have multiple generations no matter the environment as they’re designed to do so. Let’s go into the Mexican bean beetle’s life cycle in detail.
Starting with their eggs- those yellowish clusters of ovals laid random on the surface of your bean leaves.
When do they lay eggs?
Bean beetles deposit eggs in the spring to early summer. They deposit them in batches in 30-40 or so eggs on the leaf surfaces.
Female beetles feed heavily on plant matter about 14-21 days before they lay them to sustain themselves. They can cause some major damage to your bean plants during this period.
Eggs are deposited, hidden from view on leaves that are hard to see. Most will lay the eggs on the leaf surfaces and don’t bother looking for the underside to protect them.
The eggs look like small yellow ovals which are sticky and laid out in small batches, irregularly, all over the leaf surface.
Unlike flea beetles, they don’t lay them in neat rows.
Eggs take about 1-3 weeks to hatch, depending on the climate, competition, food availability, species type, and predators that eat the eggs before they hatch.
Then they emerge as those yellow caterpillars/worm/grubs and feed on your bean plant
The larvae of Mexican bean beetles look like small yellow caterpillars. Their most distinguishing features are the multitude of spikes that span their entire body.
These spikes may look alarming, but all it is is a defensive shield against predators. They would rather run away and hide than attack.
Their only job is to feed and eat up your plant foliage, which is where the majority of the damage comes from.
When people notice damage from Mexican bean beetles, the larvae are just as guilty as the adults. The adult beetles will feed, breed, and lay eggs.
You can control either part of their lifecycle, but the adults tend to leave the holes in your leaves.
The white larvae will feed on bean roots. This is generally harmless if the plant is established and you have a small number of larvae.
The larvae will continue to feed until they’re ready to pupate. During pupation, spin a cocoon and overwinter in the soil. The cold winter does not kill or get rid of bean beetles.
When springtime rolls around, they emerge and come out as the next part of their life cycle. An adult.
They pupate after 2-3 weeks of feeding. Some larvae will attach themselves to the underside of leaves and hang there to pupate.
Feeling lost? No time? No energy?
Consider talking to a professional at Terminix- one of the largest pest control companies in the US with a 100% satisfaction guarantee and alternative green control.
They'll keep coming back (at no charge to you) for additional treatments until the pests are fully eliminated.
New customers get a $50 discount off select pest services at 888-984-4396.
Call operators are available 8AM-5PM (Eastern), Monday thru Friday.
The soil pupation isn’t common in all types of bean beetles. A full cycle takes about 3 weeks and the larvae will undergo four molting cycles.
The adult forms are large beetles.
They fly or scavenge around only looking to breed and lay eggs to continue their generation.
Although they may be annoying when you harvest your beans and they fly into your face, they’re generally harmless and won’t do much damage to your legumes, peas, beans, and other crops.
It’s a two-pronged approach.
You can stop the larvae or you can stop the grown beetles Or both.
Either way will get rid of the beetles once you stop their cycle and this will get the beetle population under control.
They spend most of their time in the soil or under leaves to protect themselves. They can also be found in grass clumps or dried leaves. This is why it’s important to keep your yard clean and free of leaf litter.
They emerge in the spring (May to June) and start foraging for food.
They’ll also mate shortly after. The females lay eggs in small clusters (average clutch size is 12-50). The eggs can be found on the leaves or in the soil next to the stem of the plant.
Eggs are abandoned and will hatch on their own 1-3 weeks later depending on local climate and egg predators.
Hotter climates mean that the eggs will hatch faster. Colder temperature slows down development. Eggs hatch into larvae.
Can bean beetles fly?
They’re capable of flight with a fully developed wingspan on their backs. But they rarely ever do. They prefer to run away from danger rather than fly away.
However, you’ll still see the flutter of bean beetles now and then when you water your plants.
When are they active?
Bean leaf beetles are most active in May to June and July to September.
This varies depending on your local hardiness zone and the type of bean beetles you’re dealing with.
There are different species that exist, so some degree of habitat discrepancy is to be expected.
You’ll find that the type of bean beetle on your plants are well adapted to your native area- with a life cycle that almost perfectly fits that of the bean plant.
Why are there so many bean beetles all of a sudden?
This can be due to mild winters, which allows the bean leaf beetles to continue to stay outside for extended periods.
Their overwintering may become shorter or delayed
It may also be due to excess foliage, mulch, or snow that protects them from the elements and insulates them over the cold winter, which then results in a higher number of adults surviving the winter without a problem.
The bean beetle is active throughout the spring to early fall.
The summer is when the adults will feed nonstop and causes extensive damage to your foliage.
When the winter comes around, they’ll either burrow into the soil, take coverage under foliage or organic matter, or retreat to the woody area nearby.
Where do they come from?
The most common type of bean beetle is the Mexican bean beetle.
This one, as the name suggests, is found in Mexico and some parts of the United States.
Eastern states tend to have more serious bean beetle infestations, such as Minnesota, New Mexico, Texas, Colorado, Arizona, and other states eastward of the Rockies.
They’re also found around the Rocky Mountains where crops are bountiful and water is plentiful.
Cowpea beetles are found all over Asia and Africa- throughout the subtropics and tropics where temperatures are higher than average.
They’re an agricultural pest that prefers to feed on plants, rather than other bugs. Humid and wetter areas have more of them, as they don’t like extreme dryness.
What do Mexican bean beetles eat?
These beetles are voracious feeders and will destroy younger plants without remorse.
They like younger pods and stems which are vulnerable and easy to digest. They eat nonstop and decimate plant leaves.
Their damage caused is obvious and can’t be missed.
As their name suggests, bean beetles eat beans.
hey also eat legumes, peas, and other similar plants.
For the typical gardener, you’ll find them munching on the leaves of your younger plants and leaving behind holes or gray spots all over your leaves.
You’ll also see yellow larvae with black spikes or the actual orange/yellow bean beetle adult crawling around. Eggs may also be present on the leaves, which look like bright yellow spheres.
Some of the most common plants bean beetles are drawn to:
- Thicket beans
- Lima beans
- Green beans
- Mung beans
- Adzuki beans
- Bush beans
- Pole beans
- Pinto beans
- Navy beans
- Kidney beans
- Pod beans
- Various plant clovers
- Snap peas
- String beans
- Green beans
- Kudzu beans
- Other related crops
Mexican bean beetle damage
Their damage is extremely easy to see.
You’ll start with the yellowing of leaves and visible holes that have irregular or jagged shapes being formed on the plant’s foliage.
They eat from the top to the bottom as newer growth is tender and softer, which makes it easier for them to consume.
The leaves are left behind with skeletal remains and only the leaf veins are seen.
Silver or gray patches form on the leaf as they slowly chew through it, which eventually turns into a gaping hole right into the leaf surface.
Younger bean plants may become killed by the beetles, but older ones can tolerate damage to some extent.
If your bean plants have just developed their pair of true leaves, you’ll want to be extra careful that they don’t get eaten.
Adult bean beetles will eat the tender, younger plant foliage. If you have a lot of them, they’ll kill the first pair of true leaves and destroy younger seedling bean plants.
Established plants may have weaker crop yields. Adults also eat the pods on the outer shell, which will give the bean pods black or brown spots on them.
The pods may also be smaller or awkwardly shaped.
What beans do bean beetles prefer?
They don’t have a preference- it depends on what you have available in your garden.
If your yard has a ton of different plants, you’ll see right away which bean plant they prefer because it’ll be heavily damaged by their feeding behavior.
Bean beetles eat anything from bush beans to pole beans to seed pods that have fallen from the plant!
There have been some research studies done to show what a specific species prefers out of a small selection of plants. But in reality, this hardly helps your specific situation.
Bean beetles will eat whatever’s available as they’re scavenger and opportunistic herbivores.
Do bean beetles bite? Are they harmful?
Bean beetles don’t bite and aren’t capable of harming humans.
You should still wear gloves and protective equipment when you plan to deal with them. They’re also capable of flying but rarely will do so as they prefer to crawl with their legs.
Bean beetles can help transmit some viruses and bacteria that are specific to plants only.
So while they don’t harm humans, they DO harm plants.
How long do bean beetles live?
This depends on environmental conditions, such as temperature, competition, food availability, predators, etc. The species also contribute to variation. The average bean beetle will live for 14 days in the yard.
How do I get rid of beetles on my plants naturally?
Here are some DIY home remedies to control and get rid of Mexican bean beetles.
Remember that no two bean beetle infestations are the same.
Some of these may work for you, while some won’t. The best way to go about this is to use multiple control techniques at the same time so you find out what does work.
And then scale it up. Most of these DIY home remedies are completely natural, and some are organic control methods.
If you plan to eat these snap peas, you’ll want to stick with natural leaf beetle control.
Remove them manually
Because these beetles are big and awkward, they’re easy to pick off by hand. Put on a pair of gloves and other PPE you need.
Get a bucket of water and mix in a few tablespoons of dish soap. Stir until it suds.
Then start combing through your bean plant and remove any larvae or beetles you see. Toss them into the dish detergent and they’ll be killed in seconds.
This method works for smaller bean beetle infestations but is inefficient for later problems.
But if you just have a single bean plant, you can get rid of all the beetles just by manual removal. No chemicals or dangerous compounds are needed.
Be sure to check the bottom (underside) of leaves, stems, and other areas they’re hiding.
Note that most will drop into the soil before the cold season approaches, so you’ll find them hiding in it to overwinter.
During the summertime when they’re active, they can be found all over the leaves. Look for bean beetles from February to June.
For larger pest problems, combine manual removal with traps, sprays, repellents, and more.
It’s just one weapon in your arsenal to control, manage, and eradicate the bean beetles.
Vacuum them off
You can use a vacuum cleaner to suck up both the young larvae and the adult beetles. This is a quick way to manually remove them and clean off your plant.
A handheld, battery-powered vacuum that’s portable works best. Be sure not to get any of your bean pods or foliage stuck into the vacuum.
Dispose of the sucked up beetle debris or else they’ll escape the vacuum and infest a different part of your yard.
Does neem oil kill Mexican bean beetles?
Neem oil will kill beetles and a lot more other buggers than you’d expect.
Neem is derived naturally from the neem plant, which creates a powerful aromatic essence that kills beetles, protects your plants, and keeps beetles off for good.
Neem oil can be purchased in a pure, organic form. You’ll have to dilute it first before you spray it because it’s usually sold in high concentrations that’ll burn your plant if you apply it directly.
Depending on the type you buy, you’ll have to adjust the concentration of water to oil ratio as needed.
There are plenty of guides online you can follow to do this, or watch a video demonstrating the process, like this one:
Note that neem is dangerous to some pets and sensitive people. Neem will also harm your plants if you apply it when the sun is shining because it coats your plant with a layer of protective film.
If you apply it when the sun is too strong, it’ll burn your plant and possibly kill it.
You need to apply only when the sun is down (like in the early morning or after the sun has set). Be sure to wash off any excess neem as well.
Use as directed. The label or seller you buy the neem oil from should have some directions for pest control.
When used properly, neem oil is a very powerful beetle killer and repellent. Get the organic version for your beans because, well, they’re edibles.
You don’t want to use synthetic compounds on your edible crops.
Constantly check your plants
Just like any other good DIY pest control plan, you should constantly monitor and check on your plants for signs of bean beetles, damage, eggs, larvae, and adults.
If you know what to look for, you can effectively tell:
- Whether or not your pest control plan is working
- If you should increase or decrease management efforts
- If the beetles are thriving by the presence of eggs
- Whether or not the plants are tolerating their damage
- If new plants are affected by the beetles
- If the plant harvest if developing correctly
Check your beans every day around noon. This is when they’re most active since the sun is bright and the temperatures are warm.
Don’t check too early or too late, as bean beetles hide and you may think that your garden is beetle-free.
Most of the damage is done early in the growing season when plants are vulnerable. Look for beetles and any plant damage (holes in the leaves, defoliation, frass, or eggs).
When plants are older, they become more resistant and tolerant of beetle damage.
But when young, you should take extreme care against any bean leaf beetles especially after the plant gets its first set of true leaves.
Add floating row covers
Row covers for your bean plants can create an impenetrable barrier- protecting your most valued plants inside.
Floating covers act as a blanket over your plants that still allow sunlight and water in, but doesn’t allow large bugs to get inside.
They can keep Mexican bean beetles out because they’re too large to sneak through the filter material. Row covers come in industry-standard sizes or can be cut to size.
If you’re only growing a few plants, get the smallest size and cut as needed. Make sure to install it correctly, as even the tiniest gap between the row cover and the soil allows bugs to get inside.
Read all directions and watch some videos online for guidance.
Here’s one that gives a good overview of the process and what to expect:
They’re a fine, mesh screen that acts like a miniature tent placed over your plants.
The part that touches the soil is flat and even, so it’s best used on a flat and even surface, like a plant bed or cold frame.
When used correctly, floating row covers can prevent many different pests:
- Bean beetles
- Asparagus beetles
- Cucumber beetles
- Flea beetles
- Solider beetles
- Click beetles
- Carpet beetles
- Fig beetles
- Cigarette beetles
- Potato beetles
- Slugs and snails
Here are some of the most top rated row covers as a starting point (if you’re interested in buying):
Get rid of the eggs
The adult beetles lay eggs on the surfaces of leaves.
You can easily spot them if you look closely at batches of yellow-orange spheres glued to the leaves.
Prune the entire leaf and toss it into a soapy water solution to kill the unborn larvae before they hatch.
Apply kaolin clay
Kaolin clay is a protective coating that can be used to repel and deter beetles from your leaves.
Think of it like wax for your car’s paint finish, except kaolin clay coats your plant leaves.
It’s fine enough so that your plant can still photosynthesize and collect sunlight, but it’s thick enough so that bugs aren’t able to chew through it to get to the precious nutrients under the wax.
Not many kaolin clay products exist on the market. Any bulk bag that’s 100% natural should do the trick.
This generic 5lb bag (Amazon) should be plenty of a large garden and multiple applications.
If you decide to go this route, use it as directed.
Improper use can harm your plant by creating a too thick coating which interrupts its natural processes.
Use spined soldiers
Soldier bugs are excellent foragers for live prey. They eat beetle eggs, larvae, and even adults without question.
These are a bit harder to find online, but you can order them from specialty retailers and release them into your garden to help naturally bring down the bean beetle population. They also help control other pests like cutworms, potato beetles, asparagus beetles, click beetles, and fig beetles.
To make the most out of using spined soldier bugs for insect control, release them into a contained area with your plants that are infested.
They’ll forage and eat the live beetles until they get rid of the entire population.
Since they’re able to eat eggs and adults, they disturb the bean beetles in more ways than one.
Ladybugs will help eat eggs and smaller larvae. If you have ladybugs native to your area, you can attract more of them to help control the beetle problem.
Otherwise, you can buy them online and follow the seller’s directions to use them.
Typically, you’ll release them in small batches in your garden. They’ll forage the plants and eat up any small bugs, eggs, or larvae.
f you have smaller plants that are potted in containers, bring them indoors into a mini greenhouse and release the ladybugs there so they don’t fly away.
Or if you have a regular greenhouse, move your plants inside and release ladybugs there.
They’ll eat until there’s nothing left and take care of all the beetles. They also don’t damage your plants. Release them when the problem is taken care of.
Try pirate bugs
Pirate bugs eat beetles amongst their huge appetite for all sorts of garden pests that give people headaches.
Minute pirate bugs won’t damage your plants but will eat anything from insect eggs to larvae to entire beetles live.
If you live in an area that already has pirate bugs natively, consider attracting more of them to your garden by making it favorable to them.
Alternatively, you can buy them online in batches and release them into your garden.
The seller will have directions on how to best use them for insect control.
If you have a greenhouse, you can move your vulnerable or infested plants inside and then release the pirate bugs so they don’t escape- similar to the ladybug method above.
Green lacewings are the last beneficial insect I’d suggest because they’re a bit harder to get a hold of and maintain.
But if you’re in the right zone to raise them, they can be a voracious predator of the eggs and young larvae. They’ll eat them up until there are none left.
Lacewings are flying insects that feed on soft-bodied bugs, mites, and eggs. They can eat up to 60 aphids in a single hour!
Because of their ability to fly, they can hover around your bean plants and hunt for bean beetles all day.
They can seek out beetles hiding behind stalks, and eggs on the undersides of leaves. They’ll eat all of it. Green lacewings can be purchased online or at specialty nurseries.
Follow all directions. Use as directed. Only a few lacewings are needed to control up to 1200 square feet.
One batch lasts up to 14 days. Depending on the size of your bean plot, it can be controlled in as little as a week. Repeat batch release if needed.
Green lacewings are another useful bug to help control the population without the use of any poisonous sprays.
Remove leaf litter and organic materials
Practicing basic garden care will help keep your yard free of bugs- a lot more than you can imagine.
The reason why pest infestations often start is that they’re attracted to dense vegetation, excess moisture, or clutter to hide/breed/deposit eggs. If you control these factors, then your yard is a lot less favorable to pests in general.
So maybe instead of infesting your property, they’ll go to your neighbor’s instead.
The main thing to keep Mexican bean beetles away from your home and garden is to keep your yard clean.
Practice excellent sanitization techniques on a regular schedule, especially if you have a lot of foliage growing in the yard.
Here are some basic best practices for ensuring that your yard is less favorable to bean beetles:
- Remove ALL leaf litter- this includes any that fall behind your bushes or on your lawn
- Get rid of weeds- bean beetles like dense foliage that weedy plants provide
- Keep wooden furniture safe from borers
- Water your plants regularly, but don’t overwater
- Don’t over-fertilize, or avoid it completely
- Keep recyclables elevated- out of pests reach
- Don’t leave on patio lights or pathway lighting if unnecessary
- Protect your equipment and storage items in secure containers
- Keep your trashcan and compost bins pest-free
- Maintain water features (birdbaths, ponds, fountains, etc.)
- Regularly prune your plants to remove witling or dead foliage
- Don’t let plants become overgrown and shed their leaves
- Trim foliage to keep them shapely
- Harvest crops early and don’t let them over-ripen
- Cover, protect, and keep your patio furniture free of bugs
- Don’t let wood or firelogs be exposed to bugs
Note that the process of keeping your yard clean is completely organic. You don’t need to use any harsh compounds, chemicals, or reside to do so.
It’s just doing basic maintenance. If you’re growing edibles (peas, beans, legumes, veggies, fruits, etc.), you’ll want to stick with only organic or natural pest control.
I mean, you’ll be eating the crops and you don’t want unknown substances sprayed all over them, right?
Get rid of overwintering sites
As you know by now, the adult beetles will hide under some kind of protective shelter to weather the harsh cold in the winter.
If you remove all possible hiding places, you expose them to the cold and kill them. This goes hand in hand with keeping your yard 100% clutter-free and CLEAN.
Here are some places that bean beetles use to hide:
- Leaf litter
- Weedy plants
- Dense bushes
- Wooden logs, fire logs, or log storage
- Thick soil or mulch
- Garden storage or clutter
If you get rid of those hiding places, they have nowhere to go. You can keep your yard clean by doing regular, scheduled maintenance.
You can put your junk storage in the garage, sell it, or store it securely. You can till the soil to expose any hiding beetles.
And you can store firewood safely to keep it pest-free. It all depends on how bad you want those green beans.
Sprinkle some diatomaceous earth
Mexican bean beetles don’t tolerate diatomaceous earth at all.
DE is a natural, fine white crystalline powder that will dehydrate any hard-shelled pest that crawls over it.
When the beetles crawl over it, it sticks to their abdomen then creates thousands of tiny cuts into their exoskeleton.
They seep out precious fluids like water which then dehydrates and kills them. The powder can be found in both food-grade and pool-grade varieties.
Be sure to buy the FOOD-GRADE variant, as many people mistakenly buy the wrong one.
Food grade diatomaceous earth is commonly sold as an organic health supplement, so it’s safe for human consumption.
You can apply it to your edible plants without any problems. Read the labels and use them as directed.
Sprinkle a ring of DE around the base of the bean plant stem. This forces any leaf beetles to crawl over and make contact with the powder to get on your plant.
Then sprinkle some around the plant plot like an invisible wall to keep the beetles out.
Finally, you can add some into the soil mixture to help kill any bean beetle adults that crawl under the earth to pupate during the winter.
Plant your beans later or choose late harvest varieties
Choose cultivars that become ready to harvest in late spring.
Bean beetles have evolved to match up with the growing cycle of bean plants so they can feed on ripe crops as soon as they become available.
If you offset the harvest time of the crop by planting later, which will force it to ripen later, you’ll deal with fewer bean beetles overall.
By default, the beetles will be feeding on your ripened crop in the spring after they emerge from overwintering.
If you plant during this time, they’ll have plenty of food to eat. Ripe stems. Ripe leaves. Ripe pods.
But if you delay planting your beans, you can reduce the number of hungry beetles eating them. Wait until late spring to plant or look for late-blooming varieties of beans or legumes.
This is also an organic method to get rid of bean beetles because it requires nothing but waiting or choosing a different type of bean cultivar to plant.
Adults are active from May to June and July to September.
Use companion plants
Companion planting is the act of growing complementary plants near your vulnerable plants.
These can act as naturally beetle repelling plants or as decoy plants, which bait the beetles to eat them instead of your beans.
Here are some of the best companion plants for beans:
- Brussel sprouts
These plants won’t compete with your beans for nutrients in the soil while keeping bean beetles away. No chemicals or compound sprays are needed.
People visiting your garden won’t even know you have a beetle problem!
Using a trap crop (or fake/decoy crop) and help attract the beetles and keep them away from your beans.
This can work on smaller-scale gardens and greenhouse but isn’t effective for farms and agriculture.
If you choose to go this route, find another bean that they like to eat and plant it away from your “good” beans.
If it works, they’ll eat that instead of the beans you plan to harvest and eat.
You can also use an aggressive approach on the decoy trap crop since you don’t plan to eat it- this includes using synthetic compounds or sprays for beetle control.
Some of the most popular trap crops for companion planting are:
- Blue hubbard squash
Plant companion plants around the perimeter of your “good” crop to protect all of them from an infestation of bean beetles- like a barrier denying entry.
Any beetles that come in should be blocked out or contact the trap plants initially before seeing your other beans.
Here’s a good video that shows proper trap crop positioning:
What to spray on green beans for bugs?
If you need to use a spray or pesticide for Mexican bean beetles, here’s what to look for.
Again, I’d avoid using any synthetic compounds if possible.
If you’re growing these beans to eat, you don’t want to spray them full of nasty residues.
And if you’re sticking with organic, you’ll have to find the organic-certified variants.
Here are some active ingredients that’ll kill bean beetles and work as pesticides to help eliminate them from your garden (always opt for organic solutions when possible):
- Horticultural oils
- Botanical soaps
- Insecticidal soaps
- Kaolin clay
- Neem oil
- Rotenone dust
When choosing a product, check to see if you can find these ingredients in the list.
You can check out what’s available on Amazon.
Always use as directed by the label.
Check to ensure that BEAN BEETLE is a listed pest that the pesticide can control, or else you’re just wasting money.
Preventing Mexican bean beetle infestations
There are some things you can do to prevent and reduce the infestation of bean beetles on your green beans.
By making some minor adjustments, you can effectively reduce the overall risk of making your bean plants attractive to them so they won’t eat your crops.
Here are some tips to keep them off your plants in the future.
Keep your garden tidy
Keeping your yard clean will help naturally repel pests.
As obvious as it sounds, keeping a tidy and clutter-free yard makes it less attractive for bugs overall- bean beetles included.
This will make it less hospitable and attractive for pests because it reduces hiding places, prevents water pooling, and makes plants easier to see for pruning.
When the adults can’t find anything to eat or any beans to lay their eggs, they won’t hang around your yard.
The same goes for larvae who hide during the day. Bean beetles won’t stay around if their conditions aren’t properly met.
Reducing clutter means less hiding places for them.
Removing still water means reducing moisture. And cleaning up the plant debris means less food for bugs.
Till the soil each growing season
Every time you replant for another harvest, be sure to till the soil.
This will unearth a bunch of pupating larvae that you can eliminate before they turn into adult beetles.
Since they overwinter using the soil as a blanket, you can effectively wipe them out if you till during the peak cold season.
This will bring them to the surface of the soil and the cold will kill them. Otherwise, till in the spring when you reseed for next season and remove any larvae you find.
Plant bush beans
Bush beans are easier to grow and maintain compared to pole beans.
If you can, switch over to bush beans so you’ll have an easier time keeping it pest-free.
They’re also more hardy and tolerant to beginner mistakes when growing them at nearly no tradeoff.
Plant your crops later (delayed harvest)
Early harvest varieties are prone to beetle problems compared to late harvest crops, so grow late harvest if possible.
Some bush bean varieties are late crops, which avoids a period of when the bean beetles are most active- during the summer!
Planting crops that are late harvest will help keep them growing throughout the summer and the Mexican bean beetles will avoid them since they’re not edible yet.
By the time they’re ready for harvest, the beetles will be gone, but not your crops.
Some late harvest bean varieties you can look into are:
- Bush Blue Lake
- Roma II
- Kentucky Wonder
- Kidney beans
- Dwarf horticultural
- Fordhook 242
- Dixie Butter Pea
- Florida Butter
Attract beneficial insects
There are some beneficial bugs you can bait to your garden to help eat the beetles and control their number.
Of course, you’ll want to attract something that’s native to your area.
Here’s a list of insects and wildlife that eat bean beetles:
- Green lacewings
- Minute pirate bugs
- Parasitic wasps
- Solider bugs
- Select birds
Think to yourself: “Which one of these have I seen roaming around my yard?
Then research that specific insect, animal, invert, etc. and find out how to get more of them to your garden.
They’ll help eat the beetle larvae (or beetles themselves) and bring down their population. This can help balance your ecosystem in your garden or introduce a disturbance that may disrupt their cycle.
Spray essential oils
Essentials oils can be used as a powerful natural (and sometimes organic) repellent for bean beetles. These oils are highly concentrated and need to be diluted with distilled water.
Then they’re poured into a spray bottle and applied directly to your bean foliage, stems, and soil substrate.
If you’re growing organic beans, you can buy organic essential oils to keep that certification.
Some of the most popular bean beetle repellents are rosemary, marigold, eucalyptus, and peppermint oil.
You can buy them online or locally at specialty stores.
Note that some people and pets are sensitive to oils, so you should always send the label before you use it. Use as directed.
What to spray for bean beetles?
You should avoid using any pesticides because they often contain lingering residues that stick to the plant.
If you’re growing organic beans, you’ll have to search even harder to find suitable ones.
I’d suggest only using chemicals if you’ve tried all the natural DIY control approaches to bean beetles.
If you must use a store-bought spray, here’s what to look for:
- Neem oil-based sprays
- Lambda Cyhalothrin
Remember to read all of the warnings and use them as directed. Ensure that the bean, pea, or alguem you’re trying to protect is one of the supported plants first before you buy.
READ THE LABEL and make sure it’s right for your circumstance, plant, and pest.
Some of these will help kill the beetles while others will help keep bugs off your plants entirely.
If you want to keep it pest free, combine a beetle killer with other preventive measures, like the organic ones listed throughout this guide.
Usually, a combo of a beetle repellent, beetle trap, and bean beetle killer will be sufficient to keep bugs off your bean plants completely.
Here are some more references you may find somewhat useful:
- Late harvest beans – UAEX
- Mexican bean beetle – Wikipedia
- Mexican bean beetle – Epilachna varivestis Mulsant – UFL
- What are these little boogers eating my green beans??? – Reddit
Did you get rid of the beetles on your beans?
You should now have a solid foundation of knowledge to control, manage, and eradicate bean beetles naturally.
While they may seem harmless, they’re far from it.
These beetles will destroy your younger beans without care.
You must take action right away to get rid of them as soon as you see them. Once you notice that your plants are being eaten up, start to formulate a plan of action to eliminate them.
Do you have any questions? Do you have experience in getting these bugs under control?
Post a comment below and share your words of wisdom.
If you found this guide the least bit helpful, please let me know as well!
Consider telling a friend or your local online bean community (or neighbor) who may get some value out of it.
Thanks for reading.
Currently an active researcher in the pest control industry for the past 8 years- with a focus on using natural and organic methods to eliminate pest problems.
I share handy DIY pest techniques I come across here to help out others (and possibly save them from a mental breakdown).
Fight nature with nature.