Blister beetles are extremely common in North America, covering about 2/3 of the entire country.
They’re after your leaves, blossoms, crops, and everything else. When peak summer hits, you can expect an unmanaged yard to be swarming with them.
These little guys are relatively large compared to other beetle species (spanning up to 1″ at max height).
They’re also extremely destructive in large numbers, which allows them to destroy entire plants seemingly overnight.
To add to their reputation, they can even emit a toxin from their body when in danger.
If you crush one, it’ll release it all at once which can result in adverse reactions. It can even be lethal in high enough doses.
This is why it’s imperative you educate yourself on the behavior and management of blister beetles, but always consult a licensed professional before you try anything on your own.
In this guide, you’ll learn about:
- How to identify blister beetles and what they look like
- Why blister beetles are in your garden, home, or farmland
- Ways to naturally get rid of them without poisons
- How to keep blister beetles out of your property
- Techniques for controlling beetles in your home, garden, or plants (tomato)
- And more
If you have questions, please post them at the end of this page using the form. I’ll try to get back to you when I can.
This guide is written for quick reference, rather than being read in one sitting. So you may notice repeating themes.
Bookmark this page so you can refer back to it easier later on.
Let’s get rid of the blister beetles naturally and send them far far away from your plants.
Blister beetles should never be handled directly without proper protective gear.
Wear long sleeved clothing, closed toed shoes, protective gloves (NOT cloth), and use an object to “brush” or handle them indirectly.
If the shell is crushed, the beetle will release a toxin that will cause adverse reactions upon ingestion or contact.
NEVER attempt to handle one directly. Seek professional advice from a licensed pest control expert before attempting any insect control plan.
What’s a blister beetle?
Blister beetles, Meloidae, are small black beetles about 2.5cm in length at adult size.
There are over 250 types of blister beetles in the US and 2500 worldwide.
You’ve probably seen them scurrying about in your garden before. These guys are everywhere!
These beetles can be extremely colorful with striped lines running down the body.
They can be colored or solid. The adults have skinny legs that allow them to grasp onto plants to feed on organic matter or the larvae of other insects.
They eat both because they’re gregarious pests.
Blister beetles are a huge genus of over 2500 different types globally.
They have diversification because of their adaptations to their environments which results in thousands of unique markings, colors, shapes, sizes, and behaviors.
That can make them difficult to identify with the common person. But there is ONE thing that all of the blister beetles share- cantharidin.
That’s the poison they excrete when the beetle is killed. This tiny beetle can kill a horse if the toxin is consumed. The toxin remains dangerous even after the beetle is killed.
This is why they can be extremely dangerous to livestock for those that keep them in the garden or on the farmland.
Blister beetles found in hay or animal feed can be lethal to the animals that consume it:
- Cows (cattle)
- Guinea pigs
- Prairie Dogs
Sometimes pets like cats or dogs may eat the blister beetle residue after killing it. This is just as dangerous vs. crushed beetle juice in hay stacks.
If you have loose pets (or kids) running around in the garden where beetles are present, you need to get them under control.
Beetles may also make their way into your bedroom, kitchen, bathrooms, etc.
So be on your toes. Once you spot them inside, you know that the infestation has taken place outside. Seal your home and start eliminating them outside in the garden.
Blister beetles, being so diverse, have many aliases. Here are some of the most common names you’ll find on the web:
- Striped blister beetle
- False blister
- Two striped
- Oil beetle
Some are incorrect, but that’s expected when there are so many beetle types!
How do you identify blister beetles?
Blister beetles contain over 2500 species, so you can guess that they have a wide variety of patterns and colors.
Depending on where you live, your local beetle can have unique markings.
In general, blister beetles have a long body that’s sticklike. They can grow up to 1” in length. Their head is segmented with a neck that’s much thinner and tapers off quickly.
Their heads are big and bulky with long antennae that range up to ⅓ of their total body length. The antenna may be colored brightly from the rest of the head with the same color as the stripes on their back.
Their legs are visible with some hair on them. The legs are hairy, but the back wing covers are shiny.
Blister beetles have soft wings that allow them to fly in large swarms. The markings are bright and contrast from the dark, soft shell.
Blister beetles have unique markings that can vary a lot from one region to another. The dominant color is gray or black which is solid, but the markings are much lighter in color.
Some beetles may be blue or green with a luster. The markings are generally brown, gray, or yellow.
But again, this varies. They can even be cream-colored or some other crazy combo. The coloring is bright and variegated.
Patterns can be striped or flat. Striped beetles are usually gray or brown with yellow stripes running on the wing covers.
The most common blister beetles are the following:
- Solid gray (ash gray beetle)
- Black blister beetle is solid black
- Margined blister beetle is solid black with gray or vanilla bands on the edges of each wing cover
The trim on the margin of the wing covers is colored. Wings are flexible and soft.
During the summertime, you’ll see them everywhere as this is when they’re most active.
Overall, they’re not that special from other beetles, which can make it hard to identify them.
Proper identification is important so you know if the beetle you’re dealing with is toxic or not.
Some other beetles like the asparagus beetle are very similar in appearance, so it’s important to note the distinctions between them. Read the linked guide to spot the differences so you can properly identify blister beetles.
Blister beetles deposit their eggs in batches on the soil or under stones. Some will lay on the host plants directly. Larvae undergo four distinct instars, successively getting bigger each time.
When born from egg, the larvae will feed heavily on plant materials or eggs of other insects. Larvae have been found eating grasshopper eggs or solitary bees commonly found in pastures or grasslands where they’re plentiful.
If you’re in a rural area, you may living by pastures or grasslands. So even if you have no host crops that they eat, they may still find their way into your property.
Eggs are tiny, mobile larvae which will find bees or grasshoppers to consume. The larvae look like worms or grubs in appearance before they pupate.
Note that people mistake the blister beetle grub form vs. adult forms even through they’re the same bug.
Blister beetles spend the winter in the larvae form until the spring season where they pupate.
The adult will emerge from the cocoon about 14 days later. The adults will feed, mate, and then deposit egg clusters into the soil.
Females will mate and oviposit multiple times, but only have one progeny per year for most species. They swarm together in large numbers.
What are blister bugs attracted to?
Blister beetles like plant material, which usually includes the blossoms of flowers. Broadleaf plants are common targets with the adults feeding on flowers and some leaves.
Upon heavy feeding, they can cause your plants to defoliate which means failed blossoms. They feed on the flowers first, then move onto other parts of the plant.
Their food is insect eggs or plant materials, especially alfalfa, hay, tomato, potatoes, or other similar species.
They prefer young, tender greens because they’re easy to digest and feed on.
Blister beetles also will feed on the eggs of other insects like grasshoppers because they are easy to digest. If you have plants or grasshoppers in your garden, you can expect blister beetles to be present.
They’re really not picky about what they eat. And this is why you have blister beetles.
The majority of beetles are diurnal or show no diel cycle, which means they have little preference for the time of day they’re out and feeding.
Some are nocturnal. All are gregarious and colored for camouflage from predators.
How common are blister beetles?
With over 2500 species worldwide, blister beetles are extremely common here in the US. They’re also found in South America up to Canada!
Since they’re widely adaptable to various environments, these beetles can be found globally.
Their family of bugs spans across the world, but only a small fraction is found in the US. They’re phytophagous. They feed on plants in the Amaranthaceae, Asteraceae, and Solanaceae groups.
The crop damage from these gregarious beetles is extensive. They feed on cultivated plants. They cause defloration from their behavior.
Their local attacks can be extensive in smaller gardens.
Are blister beetles poisonous to dogs or horses?
Blister beetles are dangerous to live animals. If ingested, they can be lethal. The toxin they produce is called cantharidin.
It’s their last line of defense against predators because this toxin isn’t released until the beetle is dead. It comes oozing out of the body after being eaten during a series of controlled dispersions called reflex bleeding.
It doesn’t do anything to stop the natural enemies of blister beetles from eating it, but it does harm them after they’ve been eaten.
If the beetle is caught in the mouth, such as that of a bird, it releases the toxin which forces the attacker to let go, thus letting the beetle escape.
Cantharidin is produced between the many joints of the beetle. In this manner, the toxin is released slowly as it ends.
But if the beetle is crushed, the toxin is released all at once. It’s stable at room temperature for a very long time.
So even if you were to come into contact with it months later, the cantharidin is still effective.
In the case of being crushed in a hay bale or being stepped on by horses, dogs, or cats, can be dangerous.
If the toxin is ingested from the blister beetle being crushed, it can kill the animal.
If consumed in large amounts proportional to the animal size, it can be lethal.
Some symptoms are blistering of the mouth, throat, or digestive issues.
Small dosages can be extremely irritating to horses, cows, pigs, or other animals. Large dosages from multiple beetles can be lethal.
Where do blister beetles hide?
Blister beetle adults feed on flourishing leaves of plants.
They’re commonly found hiding in flowers that are bright and colorful where they consume the foliage, flowers, blossoms, or other tender parts.
These beetles are commonly found in the summertime during peak season. They’re not picky about what they eat. Vegetables, fruits, and even ornamental plants are all fair game for their diet.
Blister beetles are found in croplands, wetlands, and tall grassy areas. Plains, regions with dense foliage, or in the garden! They love places with lots of covers so they can hide and feed safely.
If your garden has lots of plants or planting media, this gives them ample opportunity to feed in safety.
Overcrowded plants are excellent locations for them to hide. Unkempt, messy, or weedy gardens provide plenty of coverage for these pests.
They can even thrive in the desert where they feed on the larvae of insects or flowering cacti.
Barns, farms, and crop fields are also prime targets for them to invade. Because of their small size, they can remain hidden from view for extended periods.
The major concern is their ability to hide in densely packed foliage, such as hay or other feed crops.
Growers may suffer damage to their reputation from infested bales, while buyers may suffer damage to their stock from ingesting the beetle toxins.
Beetles will eat in clusters, so if one or two are discovered, the entire bale should be considered infested.
Where do blister beetles come from?
Blister beetles natively are found in the east, south, midwest, and along the Pacific. They even span up to Quebec in Canada.
They’re found in the grasslands where they can hide their eggs in the dense foliage and have plenty of food to eat.
If you’re in one of these zones, blister beetles are likely within walking distance of your household. They’re everywhere.
What states are blister beetles found in?
Blister beetles are found in the southern and eastern regions of the US. They’re basically present in 2/3 of the country!
The following states have a native blister beetle population:
- North Carolina
- Washington DC
- North Dakota
- New Hampshire
- South Carolina
- North Carolina
- South Dakota
Outside of the US, they span up to Canada and down to the South Americas.
What do they eat?
Blister beetles eat anything and everything. They’re a major threat to farmers who have crop fields.
They also damage the garden, commercial, leaf crops, alfalfa, hay crops, blossoms, and landscape plants. They’ll eat anything. Nearly any leaf in your garden is fair game.
Solanaceae vegetables, leafy greens, and everything in between. They’re most active in mid or late summer when they show up in large swarms.
Because of this, they can wipe out your foliage in a short period.
The majority of blister beetles only eat floral parts, but some will eat the foliage as well. Some will eat insects.
Since they’re so diverse, they’ve grown a large appetite for most plants and insects.
They can eat eggs, larvae, or even entire bugs.
Plant-wise, they can be found munching on legumes, beet, potato, grasses, alfalfa, hay, fruits, greens, vegetables, or even beans.
People in online gardening communities have reported blister beetle infestations in their peppers, eggplants, turnips, beans, peas, peppers, tomatoes, potatoes, and other dark leafy greens.
Younger seedlings are especially vulnerable to their destruction. They like foliage that’s tender and easier to digest.
For the common person with a garden, blister beetles are a nuisance.
For farmers with croplands, they can do millions of dollars worth of damage.
Blister beetles are a real threat to crop fields that contain alfalfa, beet, tomato, potato, straw, or hay.
Because it provides them with plenty of food and they swarm in huge volumes, they can absolutely decimate fields.
This is why so many publications are written about blister beetle damage, especially in states like Florida. They’re not playing around, friend!
Do blister beetles fly?
Blister beetles can definitely fly. They have large, flexible wings that are actually functional.
Unlike some other insects where the wings are there but they don’t do anything, blister beetles are capable of flight in large swarms that buzz around large crop fields in the heat of summer.
If you’ve ever messed around in your garden and a bunch of beetles just flew out, it can definitely be blister beetles.
Are blister beetles beneficial?
Even as scary as they sound, there are some redeeming qualities to blister beetles.
They actually have some benefits that should be recognized:
- Blister beetles eat grasshopper larvae which can help reduce grasshopper populations
- Blisters eat wild bee larvae and destroy the hive (though bees are important pollinators)
- Blister beetles can help consume plant material
- Grasshopper control
For most people, these reasons aren’t good enough to keep the blister beetles around. If you own horses or other animals, blister beetles can pose a serious threat to them.
Or if you’re scared of accidentally coming into contact with the toxins, it can make your life that much more complicated.
Do a lot of gardening? Blister beetles should be managed, controlled, and eliminated from your garden.
The grasshopper is a major pest in the farming industry. It’s also a nuisance in the home garden.
Grasshoppers will consume plants with great force. Blister beetle larvae will seek out batches of grasshopper eggs to eat with their legs.
But this is only when they’re nymphs. Once blister beetles grow up to adult size, they start doing the real damage to your plants.
So in a sense, yes, they can be used to control grasshopper populations. But after they grow up, they’re a nuisance.
Are blister beetles dangerous?
Blister beetles are aptly named “blister” because of the toxin they release when crushed.
If you’ve ever smashed one on your skin, you’ll notice that the skin gets irritated from the beetle’s poison which causes a painful blister.
This is why you should never attempt to handle, kill, or otherwise make contact with a blister beetle without protection.
Cantharidin, their toxin, is actually used to help reduce warts. But if swallowed, it can be dangerous.
Even just 5 grams or less can be lethal depending on the type of beetle. If ingested by humans, severe damage to the urinary tract and gastrointestinal damage is to be expected.
While blister beetles don’t bite humans, the toxic residue they emit can be extremely irritating.
If a beetle lands on your skin, don’t crush it. Blow it off instead. If you crush it, you force it to release its goo which will get your skin some painful blisters.
If you’re situated in an area where blister beetles are abundant, avoid smacking something on your skin when you don’t know what it is.
Remember that blister beetles will be active during the day for most species.
They also exhibit phototaxis, which is an attraction to light.
So at night, they hover around porch or patio lights which can bring them on your skin. Avoid killing it on your skin.
Don’t ingest the beetle. It can be lethal if ingested orally or even through the skin. The chemical cantharidin will blister your skin and look terrible, but usually will go away on its own.
Consult a medical professional for advice. If it gets into your mouth, eye, nose, cuts, or otherwise inside you, get medical assistance immediately.
Wash all surfaces the bug has touched. Avoid touching your face or eyes upon contact. Don’t touch the parts of your skin it touched without washing it thoroughly first.
Wear long pants, long sleeves, and thick clothing. Blistering will occur on the skin where the beetle touches.
Thin skin is even more vulnerable. These beetles are big and scary, but you should just brush it off with something else.
Clothes, napkins, or something so you don’t need to touch them. Just don’t crush it. Remember it doesn’t bite, so don’t be in a hurry to remove it. Light brushing or washing it off is good enough.
Wash any clothes or surfaces it comes into contact with. If you brush it off too hard, it may release its toxin, so be gentle!
Some beetles are more poisonous than others.
Typically, blister beetles found in hay are the most serious threat to livestock that may consume it.
Horses, cows, pigs, chickens, or other animals that can ingest crushed beetles can end up eating the toxin.
When blister beetles are crushed, they release all of their poison at once.
What kinds of beetles are found in hay?
Hay bales tend to be a favorite place for beetles to congregate.
Within hay, these are the most commonly found species:
- Black blister beetle
- Three-striped blister beetle
- Spotted blister beetle
You should always purchase hay from a reputable seller who can offer a certificate of inspection for blister beetles.
Hay growers who check their bales for beetles regularly will charge a premium, but you have a lower risk of getting your livestock sick from eating the beetle juice.
Buy first cuttings if possible. This is less likely to be infected compared to second or third hay cuttings.
Avoid using hay crimpers because they’ll kill the beetles which resell the chemicals.
Let the hay sit for a few days on your farmland to release the bugs. Cut the hay and let it sit. This will encourage the beetles to leave the bale. Do a visual inspection to check for beetles.
If you see even one or two, it’s a good chance that the entire bale is infested.
How to get rid of blister beetles naturally
Blister beetles are difficult to completely get rid of because they swarm in such numbers.
You can do some basic, DIY remedies that can help bring their numbers down so you limit the damage done to your garden.
The goal of this isn’t to fully eradicate the beetles. Whoever promises you that is lying. It’s more of “damage control” so you can still enjoy your flowers or reduce damage to your crop yield.
Check these techniques out and gauge what works for your situation.
Manual removal of blister beetles
You can manually remove the beetles to help control the population, but you’ll need some protective gloves before you do so.
Make sure the gloves are thick and in good condition.
Prepare a bucket of soapy water by diluting soap into a mixture of 1:10 water. Stir it gently until it suds up.
Go out into your garden and it’s time to go beetle hunting!
This is the easiest way to get rid of a blister beetle infestation that’s completely natural and organic!
The ideal time to look for blister beetles is during the morning to afternoon.
They’re active during the daytime (diurnal) so you’ll find them munching on larvae or eggs or plant matter during the day.
Place the bucket under the plant and then gently knock them off into the bucket.
Do NOT crush them or touch them directly. Just grab the plant and then shake it so they fall into the soapy water.
When blister beetles are disturbed, they’ll stop moving in place.
For the beetles that miss the bucket and fall onto the soil, gently pick them up and put them into the bucket of soapy water.
They’ll be killed within a few minutes. Beetles that aren’t killed will climb back onto the plant and start eating again.
So don’t ignore the ones you miss! Dispose of the soapy water carefully because it’s a biohazard.
It contains large quantities of the cantharidin toxin so it needs to be properly disposed of. You can brush them off with a paintbrush into a small container.
Shaking it will often scatter the pests all over your garden where they’ll lie there and play possum. Gather them carefully during this opportunity.
Get rid of grasshoppers, eggs, and larvae in y0ur garden
There are some eggs that blister beetles will seek out more than others. Grasshoppers are one of their favorites.
If you’re located somewhere where grasshoppers are a native species, consider eliminating the grasshoppers from your garden first.
This will then provide less food available for the blister beetles, which means your yard becomes less attractive to blister beetle females looking for somewhere to deposit their eggs.
If you let the grasshoppers go crazy and deposit their eggs all over your tall weeds, then you’re just inviting the blister beetles in.
The eggs provide the beetle larvae with plenty of food to consume when they’re growing.
Some insecticides that contain the compound spinosad are efficient because it kills both grasshoppers and blister beetles simultaneously.
Note that spinosad doesn’t work immediately. It takes about 2-3 days for it to work in full force.
When used properly, spinosad isn’t known to be dangerous to wildlife or beneficial insects, birds, fish, or other animals. But it DOES kill bees, so keep that in mind.
Grasshoppers eggs are one of the prime staples in the blister beetle food chain.
If your garden is prone to grasshoppers, you’re basically providing them a buffet of eggs to eat to feed the larvae. Keep grasshoppers under control using DIY remedies.
The presence of grasshoppers in your garden shouldn’t be ignored as they’re destructive to crops themselves.
So it’s not just the beetles you’ll be dealing with- the grasshoppers will destroy your plants just like the blister beetles!
There’s no real benefit to keeping the hoppers in your garden, so get rid of them.
Don’t use poison or synthetic sprays if possible. These are highly unnecessary especially if you’re growing edible plants.
Grasshopper populations can be controlled using basic home remedies. No need to go out and buy a bottle of grasshopper spray with unknown substances.
Eliminating the grasshoppers will help eliminate the beetles. They’re paired.
Check your garden often
Whenever you’re out in your garden, do a quick inspection for blister beetles.
This means when watering your plants, pruning, cleaning, raking, harvesting, picking, or doing other yard work.
Check for blister beetles regularly then take action if you spot them. You’ll often find blister beetles early in the summertime or late spring. You just see a few of the early scouts during the early season.
Then you’ll find the big swarms later in the season.
The key is to find them early in the season so you can prepare for the swarms.
Check your easy target crops like lettuce, potatoes, tomatoes, kale, spinach, or other leafy greens.
Blister beetles often eat the low-hanging crop that’s easy to digest and widely exposed. Note that site.
Check it daily for most beetle activities. They’re not that smart and will continue to gravitate towards the same plant materials until they’re depleted.
Some people even plant decoy plants as early warning signals. You can do the same with plants you don’t care for.
Checking your home and garden of blister beetles can do a lot of good for controlling their damage.
When you see their numbers improve for the summer, being observant can tell you your next move in your plan of action for DIY pest control.
Blister beetles will show up in the largest numbers in July. If your yard is suddenly overwhelmed by these leaf-eaters, you can remove them in huge numbers before they hunker down in your yard.
If you wait, it’ll get extremely difficult to spot them once they burrow themselves into your garden.
When they’re still on the leaf margins of your potatoes or lettuce, it’s easy to get rid of them right then and there.
Beetle infestations will first show up at the edges of your garden. Keep your weeds, grass, or other plants carefully pruned and tidy.
Or just removed the margin bordering plants entirely.
If you spot beetles on the leaves or flowers, act quickly. Remove them manually with the protection of course.
Dunk them into soapy water to kill them. It’s rare to find just one or two beetles. You’ll find them in swarms.
Check daily until they’re completely gone. If they get into your plants, they can hide until you leave them.
Clean up your yard
If your garden hasn’t been tidy of late, you may want to take the chance to clean it up.
Blister beetles are attracted to dense foliage from plants or tall grasses. Weeds are also a thick plant cover that adult beetles will congregate into to deposit eggs.
Weeds not only bring in blister beetles but other insects which may lay their eggs in the foliage.
This provides the blister beetle larvae food to eat- the larvae of OTHER insects.
Basically, the more pests that thrive in your garden, the higher the chance of blister beetle infestation. They have plenty of eggs, nymphs, and plants to eat.
Keep your garden clean to keep blister beetles out:
- Mow your lawn
- Clean up grass clippings
- Remove weeds immediately
- Remove plants that you no longer want or care about
- Trim and prune foliage
- Keep plant leaves tidy and compact
- Don’t let plants grow too crazy
- Keep water features clean (birdfeeders, birdbaths, ponds, pools, etc.)
- Avoid overwatering
- Ensure that water drain ways are clear
- Don’t use plant food/fertilizer if unnecessary
- Clean up leaf litter immediately
- Don’t plant weeds or remove them entirely (pigweed, ironweed, ragweed)
Beetles often will feed on weeds or leafy greens first.
Then they’ll move on to your other plants or insect eggs/nymphs. They go for easy targets that are easy to digest.
Why? Because it expands less energy so they conserve their precious calories from mating, breeding, and feeding!
Doing these things will not only keep blister beetles away but will help keep other insects out of your garden as well.
If there are fewer insects, that means there are fewer eggs. If there are fewer eggs, then there’s less food overall for the blister beetles to eat.
This means your garden can’t sustain a huge population of them since the ecosystem is limited to just what it can provide.
Not enough food? Then there can’t be huge swarms of bugs!
While the beetles can still eat the plant materials there, they’ll have fewer insect eggs to eat (think grasshopper eggs).
So if you combine the total aggregate food availability from both the plant and the insects, there’s less food overall once you remove the insect component of it.
Therefore, you effectively eliminate a good piece of their overall food supply! This controls the maximum amount of blister beetles that can be sustained in your garden overall.
Just by keeping it clean, you can passively get rid of blister beetles naturally without even a single spray.
Install floating row covers
Row covers are a good, effective way to keep pests out of your plants.
They’re a physical barrier that can be purchased for cheap in bulk at your local home improvement store or nursery.
Row covers are only useful if they’re the right size and set up properly. Think of them like bird netting: if the hole isn’t the net is too big, then pests can just go right through it.
So it’s useless. But if you get a size that’s small enough to stop the beetles from getting through, but also allows you to water your plants, then that’s perfect.
The point of the row cover is that it lets you feed and water your crops without disturbing them at the same time while keeping bugs and birds out.
You can find all sorts of row covers online (check on Amazon) in different sizes. Find a roll that fits your garden.
This is the hard part- you’ll need to do some measurements to find out how much you need, how thick, and how wide.
Once you’re done, it’s just a matter of properly installing it into your garden.
Row covers will prevent the blister beetles from coming into your crops, but don’t stop the small blister beetle larvae from emerging in the springtime.
So it’s best used when combined with some other DIY natural remedy.
Just using row covers only prevents the adults from coming in to feed on your crops or laying off eggs on the leaves.
But it doesn’t stop the tiny nymph beetles from getting in to feed.
Store your plants in greenhouses
For portable plants that are grown in containers, you can move them into a secure greenhouse during peak beetle season.
This will completely protect them from the beetles, as long as you don’t let any smuggle themselves into the greenhouse.
When you enter/exit, do so with caution to make sure that the beetles don’t get inside.
Greenhouses aren’t for everyone, but they make pest management so much simpler if you have one.
Don’t plant pigweed
Pigweed is surprisingly attractive to adult beetles. If your landscape with this weed in your garden, get rid of it.
No matter how much you like it. This weed is one of the blister beetle favorites, along with their cousin’s ragweed and ironweed.
This goes for neighbors as well. If any of you have these weeds growing in your garden, you’ll bring in blister beetles like crazy.
If you don’t know your weeds, here’s a good resource you can use to help identify them.
Use oyster shell lime
Oyster shells are delicious, but did you know they can double as a DIY physical barrier against beetles?
Oyster shells don’t kill the blister beetles, but help discourage them from coming to your garden.
You can use crushed oyster shells or whole shell lime. Place them in strategic sites in your garden.
It’s a completely natural way to help keep the blister beetles out. It’s used as a natural beetle repellent.
Plus, it helps establish the proper soil pH.
So it’s excellent for natural beetle repellent. You can find oyster shell lime online (see Amazon) for cheap or in your local store that carries it (check nurseries or home improvement stores).
Check your garden perimeters
Blister beetle infestations will show up at the field edges first.
If you check these areas often, you’ll be able to spot them before they make their way into your deep garden.
Keep an eye on your crops and eliminate the insects as they show up. Clear out sections with beetles.
For framers, avoid using equipment that can crush the beetles hiding in the hay. First cuttings of hay are generally safer.
Use diatomaceous earth
Diatomaceous earth is a natural fine white crystalline powder that can be used to dehydrate the bugs.
You can find organic food-grade DE online (see Amazon). Don’t get the pool-grade one- it’s not safe for consumption if you’re growing edible plants like tomatoes or potatoes.
Sprinkle the powder into powder and on the surfaces that the beetles are feeding on. Upon contact, they’ll dehydrate because the fine crystalline structure pierces their outer hard body.
It’s especially effective against beetle babies as they crawl over it multiple times foraging for food. The nymphs don’t have wings yet, so they have no choice but to touch the DE.
Use in conjunction with oyster lime or row covers. The covers can block the large adult beetles from getting into your plants to deposit eggs. The DE or oyster lime can kill the nymphs that sneak in through the gaps.
Do blister beetles have predators?
Blister beetles have a few natural predators that’ll feed on them, but they’re not easy to “get” into your garden. So that leaves us with birds.
You may consider using them to your benefit if you’ve got these predators in your area.
Birds will gladly gobble up blister beetles.
Encourage birds to come into your garden to help feed on the beetles by doing things that bring them in like setting up birdbaths, birdfeeders, etc.
Depending on the type of birds native to your zone, you’ll have to do some reading on how to lure them in.
But once you get them coming, they’ll return daily to feed on the beetles. Don’t use compounds that may repel or harm the birds. Respect them.
How to get rid of blister beetles in the house
Blister beetles may accidentally get into the house. But they don’t generally wander in for no reason.
There’s likely something they’re after if they get inside. You shouldn’t worry too much though, because if your indoor plants are under control, they don’t have anything to eat.
Thus, they’ve got nothing to infest. So beetle infestations generally clear up on their own. Unless you’ve got them outside your home. Then batches of them will show up inside until peak season is over.
There are multitudes of possibilities why blister beetles are in your house:
- The temperature outside is too hot or cold, so they’re seeking shelter from it
- They may have been carried in by wind currents
- They may have been smuggled inside from infested fruits or veggies from your garden
- Houseplants may be infested from the nursery
- Blister beetle entry from windows, doors, etc.
- Change in humidity
- Change in weather
Blister beetles have nothing to invest inside the household, so you should just carefully catch and kill the ones you find. Remember to NEVER touch it directly.
Use a broom and dustpan to sweep them up without crushing them or else they’ll release their toxin.
If you must pick it up by hand, use gloves that aren’t cloth. Use something to grab them so you don’t contact them directly, such as a small brush.
When you’ve manually cleaned up loose beetles, here are some things you can do to prevent them from getting inside your property:
- Repair damaged screens on windows
- Seal or caulk cracks in the exterior walls
- Check for foundational cracks
- Turn off inside lighting at night
- Use blinds or curtains to stop light bleeding to the garden
- Turn off patio lights, pathway lights, or other unnecessary lighting
- Check HVAC grates for damage
- Use doors quickly
- Don’t open windows
- Inspect then quarantine new plants, harvest, fruits, or veggies before taking them inside
- Get rid of indoor plants temporarily until you’ve taken care of the infestation
- Don’t buy new soil or plants in the meantime while you’re getting rid of the blister beetles
How to get rid of blister beetles on tomato plants
Blister beetles on your tomato plants can be controlled using the techniques found in this guide.
Use a combination of various home remedies like installing row covers, sprinkling diatomaceous earth, using oyster lime, keeping your garden tidy, encouraging bird activity, and using spinosad if necessary.
Start from the easiest treatment then move on to the stronger techniques. Tomato flowers will be eaten by the pests first, then they move on to the other parts of the plant.
Using row covers on the tomatoes to provide a physical barrier helps keep the adults out from laying eggs.
Putting some oyster lime on the inside makes a one-two combo for full protection.
While no tomato plants are completely safe from blister beetle damage, you can greatly reduce it.
How to get rid of blister beetles in hay
Blister beetles found in your hay bales are hard to eliminate. The easiest way is to use a reliable hay grower that you know and trust.
They should have a good reputation, but even then, you must carefully examine the hay flakes for signs of beetles.
- Look for visible beetles, beetle frass (beetle poop), or flying beetles that escape once you disturb the cutting.
- Note that beetles will play possum so you may not be able to see them running around so easily.
- After buying the bales, there are some other things you can do to help eliminate the possibility of infestation:
Place the bales in the sun in a quarantine area away from your hay stash, feed, crops, etc.
Let it sit there for a few days. This will encourage beetles hiding in it to leave the bale since there’s no food.
Check manually for beetle activity.
Buying hay feed from reputable growers, then doing some manual inspecting is what you can do to prevent blister beetles in the hay.
If you don’t trust the grower, then don’t buy. Ask them about beetle presence in their product before buying!
There are a lot of sprays out there for beetles, but only a few are organic or safe for edible plants.
Whether you’re growing something edible or not, consider going green because it’s safe for your, your pets, and the environment. Not to mention sensitive individuals who may visit your yard.
Regardless, make sure you read the label and use the pesticide as directed.
What insecticide kills blister beetles?
Spinosad is an effective insecticide that you can spray to help kill blister beetles.
This is considered to be an organic ingredient, so if you’re growing organic veggies or fruits, it may be worth considering as a last resort insect remedy. You should always read the warning label and use it as directed.
Some people spray their alfalfa hay that’s been infested with spinosad. This may be appropriate, but only if directed by the label. Consult the manufacture if you need assistance.
If you’re using it on edibles, be sure that it’s safe for them.
Spinosad can be found in a variety of bug sprays. Blister beetles should be clearly listed on the label as a target insect before you buy them or else it may be a waste of your money.
It’s an OMRI-listed pesticide, so it’s safe for organic gardening when the right type is used for the right application, so don’t just go buying anything with spinosad in it. That’s not how you do it.
Here’s a products from Amazon that may be worth considering:
Additionally, spinosad will break down into inert ingredients when used in the sun. Read the label. It’s more about using it at the right time.
- Blister Beetles | Entomology – University of Kentucky
- Blister Beetles / Alfalfa / Agriculture – UC IPM
- Dealing with Blister Beetles – UNL Beef
- Blister Beetle in Alfalfa – CropWatch
- Blister Beetles – Department of Entomology
Did you get rid of the blister beetles?
These beetles are scary in huge numbers so you should act quickly to eliminate them if you wanna save your plants from being eaten.
Do your regular garden inspections for beetles in the early spring to spot them, then formulate a plan of action to get rid of them.
It’s not possible to completely eliminate the beetles entirely if you’re in a zone that they’re native to.
But reducing the damage can be done through the means of using natural repellents, and physical barriers, and then using organic sprays as needed.
Do you have questions about your specific blister beetle infestation? Post them below using the comments form and I’ll try to get back to you ASAP (as usual).
If you found this guide helpful, please let me know. Or if you have any feedback for improvements, please do the same!
Consider telling a neighbor or friend who may be going through a nightmare dealing with these bugs- it’s the most you could do for me!
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.