Blister beetles are plant pests, and you should try to remove them if you spot them in your yard. So, what do blister beetles eat? Which plants are at risk from them? Let’s find out.
Anytime you see a brightly colored beetle, take it as a sign of their toxicity and stay away!
One such beetle is the blister beetle.
Their name comes from the painful blisters they can cause on human (and animal skin).
Blister beetles produce Cantharidin as a defense mechanism against predators (and their bodies continue to secrete this, even when they die).
These beetles are pests that feed on flowers and sometimes tender shoots, with the instars feeding on insect eggs.
They also love munching on crop plant leaves, such as those of tomato, potato, eggplant, beans, and peppers.
In this article, we will talk about what these beetles eat and who eats them.
What Are Blister Beetles?
Blister beetles are soft-bodied insects belonging to the Meloidae family.
There are over 2500 species of blister beetles, with 26 found in Florida, the US itself. Moreover, they have multiple subfamilies and genera within these species.
These beetles have soft, elongated bodies, with a head that is bent downwards and a thin neck portion.
Likewise, they’re quite similar to beetles from the Oedemeridae, which are known as false blister beetles.
What Do Blister Beetles Look Like?
Beetles of the Meloidae family can have a variety of colors, depending on the species.
Some Common Blister Beetle variations are gray bodies with black marks, fully black bodies, ash gray bodies, and brownish-reddish bodies.
Some species, like the Hycleus lugens have bright yellow dots to warn predators of its toxicity.
Some, like the Pyrota lineata are orange in color with black striations on their bodies (striped blister beetles).
Under the subfamily of Meloidae, we have various types of blister beetles tribes, such as Cerocomini, Epicautini, Eupomphini, Lyttini, Meloini, Mylabrini, and Pyrotini.
The larvae of all species look similar – with a boat-shaped body and setation patterns on their bodies.
A common way of distinguishing the larvae from that other beetles is that they have only one or two stemmata (eyes) on the sides of their heads (as opposed to other species, which have four or five).
What Do Blister Beetles Eat?
Blister beetles have a diet that varies as they move on from instar phases to an adult.
As adults, they are generally found in fields with flowering plants, but as larvae, they are predaceous.
What Do Adult Blister Beetles Eat?
Blister beetle adults mainly feed on flowers. Some common plant families they attack are Amaranthaceae and Leguminosae.
Some adult beetles also eat soft leaves or tender-shoot plants. They usually attack plants in a swarm.
This is commonly seen in beans. Blister beetles of the Epicauta subfamily are known to eat plant leaves.
Apart from flowers, they also attack the leaves of various plants.
What Do Blister Beetle Larvae Eat?
In their larval stages, blister beetle instars feed on the eggs of the acridid grasshoppers.
Some larvae, during their first instar stage (also known as the first grub phase or FG phase), feed on bees.
Larvae do not generally harm plants.
Some feed on the eggs laid by other blister beetles.
Feeding on eggs of other species is also common. For e.g., larvae of the Epicauta species have been found within the egg nests of the Melanoplus species.
Are They a Serious Crop Pest?
Blister beetles can be a serious crop pest, depending on the specific species and the crops they infest.
They attack the leaves of plant crops such as tomatoes, potatoes, eggplants, beans, and peppers.
Several species of blister beetles are known to damage tender crops, such as alfalfa and beans.
When these beetles feed on crops, they can cause defoliation, stunting, and even death of the plant.
In addition to damaging crops, blister beetles can also pose a risk to humans and animals, which we will discuss next.
How Blister Beetles Can Be Bad For Livestock
Apart from the fact that they can cause blisters in humans, blister beetles are toxic for livestock and poultry.
Their bodies secret a chemical called Cantharidin. Cantharidin oil is obtained from the bodies of crushed beetles.
This oil can poison livestock, and the amount produced by a total of 30 to 50 beetles can be fatal for even a horse!
Some common symptoms of this poison are sores in the cattle’s mouth and body, blood in urine and stool, colic, and depression.
To prevent blister beetle poisoning, it is important to ensure that they are not hidden within hay bales.
They can easily get crushed and poison the bales.
If you have alfalfa fields, harvest before bloom to prevent infestation, which can help prevent deaths in horses.
How To Prevent Blister Beetle Infestations
If you want to secure your crops and livestock, here’s what you can do:
- Diatomaceous Earth – You can sprinkle the Diatomaceous Earth mixture near the roots of your plants. This siliceous earthy mixture will kill existing beetles and prevent future infestations.
- Oyster lime shell – Similar to Diatomaceous Earth, you can prepare the soil with oyster lime shell mixture before planting to prevent beetle growth.
- Neem Oil – Spray a mixture of neem oil and soapy water onto the beetles. Make sure to protect yourself with gloves and the necessary clothing during this. The mixture will make the beetles sterile.
- Manual extermination – With the proper gear, you can exterminate the existing beetles by hand after stunning them using the neem oil mixture or pesticide. After you collect them, drown them in a soap-water mixture. Make sure to remove any clusters of eggs as well.
Beneficial Insects That Can Help Remove Blister Beetles
Alternatively, you can try getting rid of them in an organic way:
- Common predators of the blister beetle include small reptiles, including frogs and lizards
- Some birds, and smaller mammals can also feed on them.
- Larvae of some insects, such as Lacewings, are known to prey on the grub of beetles.
- Starling and robins are birds that commonly eat beetle grub.
Frequently Asked Questions
Do blister beetles bite humans?
Blister beetles do not actively bite humans or animals, but contact with their toxins can lead to skin inflammation.
Blister beetles secrete a toxin called cantharidin that can cause skin irritation and potential allergic reactions.
Treatment for blister beetle bites includes using over-the-counter hydrocortisone cream or calamine lotion, taking antihistamines such as Benadryl, and avoiding scratching the affected area.
To avoid contact with blister beetles in your home or garden, be aware of signs of their presence and take precautionary measures.
Are blister beetles beneficial?
Although blister beetles may sound like a nuisance to humans, they can also be beneficial insects in agricultural ecosystems.
Their larvae feed on pest species that can damage crops, such as grasshoppers, caterpillars, and armyworms.
To keep these pests from doing major damage to crops, farmers have started using blister beetles as an organic form of pest control.
However, because blister beetles release toxins when handled or squished, it’s important for farmers to take safety precautions when introducing them into the environment.
Where do blister beetles lay eggs?
Blister beetles lay eggs in a variety of places, such as in the soil, or on leaves that they feed on. Typically, the eggs are laid in small holes about one or two inches deep in the soil,
The females will typically lay their eggs within one or two weeks after mating.
The eggs are small, oval-shaped, yellow, or cream-colored when newly laid and turn grayish as they get older.
Generally, the larvae will hatch after about 10 to 16 days, depending on the weather conditions.
Once they have hatched, they will feed on grasshopper eggs and other insect eggs in the soil.
After this, they move through several instar stages before reaching a pre-pupation stage and then overwintering to come out as adults.
Can blister beetles fly?
Yes, many species of blister beetles are able to fly.
Blister beetles belong to the family Meloidae, and a majority of them have wings under their hard exoskeleton and can fly short distances.
Depending on the species, some blister beetles may move around by jumping or even swimming instead of flying.
However, most blister beetles do have the ability to fly.
Blister beetle grub can also be beneficial since they eat up grasshopper eggs.
In fact, as long as you don’t have flowering plants and cattle, you might even prefer having them around.
However, the adults are ferocious eaters of crop plants, including potatoes, peppers, tomatoes, or any other plant that has leaves.
They also attack some common ornamental flowers.
Moreover, these bugs are particularly dangerous to livestock because they emit Cantharidin, a poisonous substance.
It is best to try and get rid of them. Smaller reptiles, such as frogs and lizards, can do the job for you.
Lacewing larvae are also good at feeding on the larvae of these beetles. You can introduce them to your garden to get rid of blister beetles.
Thank you for reading.
Considering the damage that blister beetles can cause to home gardens and crop plants, these beetles have often been the subject of our reader’s letters.
We have collected below a few of them for you to go through and understand the kind of damage blister beetles can cause
Letter 1 – Master Blister Beetles Mating and Eating
Mojave Desert Insect Identification
I’ve attached several photos of an insect we found near Davis Dam which is in Bullhead City, Arizona. There were between 50 and 100 of them sitting in a localized area crawling to the top of local wild flowers, mostly on the Phacelia Distans. Also known as Blue Phacelia, Wild Heliotrope ~ Scorpionweed. At first I thought they were Tarantula Hawks, but their color and shape was wrong. They look similar to your Spider Wasp photos. Their sizes varied between 1 inch and nearly 3 inches for the bigger of the group. Some appeared to be stuck together end to end (mating I guess.) They were pretty aggressive. They would follow you on the ground trying to get onto your boot and would actively follow your position with their little head. However, most refused to fly thankfully. These insects stayed in this place for at least the past two days. I was able to get within 6 inches of them with the camera without disturbing them. We’re interested to know how dangerous they are beyond someone simply being allergic and doing the curly shuffle in a circle on the ground in anaphylactic shock. Feel free to use the photos for whatever you like. The photos were taken on 3/22/2008. Thanks,
Project Manager — Davis Dam
These are Master Blister Beetles, Lytta magister. They are known as Blister Beetles since they can secrete a substance from between their leg joints that will cause an irritating reaction in humans.
Letter 2 – Blister Beetles
4 pictures for you
What kind of beetle. Rural Ottawa, Ontario Canada. There’re defoliating my lupins. How do I get rid of them?
These are Blister Beetles in the genus Lytta. We found a match from Canada on BugGuide, but it is not identified to the species level.
Letter 3 – Caragana Blister Beetle maybe
What kind of beatle is this?
This picture was sent to me by a freind who is doing a Bald Eagle study near Needles Eye of the Gila river in Arizona.
We were unsure so we contacted Eric Eaton. He also wanted to be positive, and he wrote back: “I queried Dr. Carl Olson at the U of Arizona, and he suggests it is most likely a blister beetle, MAYBE Lytta viridana. Meloids were on my short list also, so you can draw your own conclusions. Thanks.
So while we are not 100% positive, I hope this helps. The common name for this beetle is the Caragana Blister Beetle.
Thanks, I will check with Carl Olsen myself too. I used to date one of his students and forgot all about it. I have thousands of bug pictures I need to get identified. If I get the time to sort them out I will send them in. I am out in the field most every weekend and about 3 times durring the week looking for herps. If ya all need any pictures let me know.
Letter 4 – Blister Beetle: Megetra
Is This a Blister Beetle????
We live in Deming, New Mexico (located in the southwestern corner of New Mexico) and keep seeing this Beetle (?) and have checked your website. It is similar to the Blister Beetle pictured on your website, except that our beetle seems to be longer than the one pictured and is triangular in shape. Are we correct in assuming it is another variety of Blister Beetle??? Thanks so much.
You are correct. This is a Blister Beetle in the genus Megetra.
Letter 5 – Blister Beetle: Megetra species
New Mexico beetle
On a trip from Oklahoma to the west coast, I came across dozens if not a hundred or two of these beetles alongside I-40 in mid-New Mexico. I have had no success online in finding the ID. I will watch with interest for enlightenment. Thank you,
Oklahoma City, OK
Congratulations on recognizing this as a beetle. It is a Blister Beetle in the genus Megetra.
Letter 6 – Florida Blister Beetle
Love your site! Took your advice and purchased Kaufman Field Guide to Insects of North America to aid in identifying the interesting insects I often photograph. However, after searching the book and through all your pages of beetles, I couldn’t identify this guy (or gall). It appears to be a beetle, but can’t determine for sure. The photo was taken in Florida on April 18, 2002. Any ideas?
This is a Blister Beetle in the family Meloidae. We believe it is the Florida Blister Beetle, Epicauta floridensis, based on images posted to BugGuide. We will consult Eric Eaton, who authored the Kaufman Guide, to see if he agrees.
I agree the blister beetle is in the genus Epicauta. Beyond that, I can’t say. Epicauta is probably decades overdue for a revision, and I dare say that molecular studies will reveal many more species than are presently described. Sometimes, identification to only genus level (or even family in some cases) is quite an accomplishment all by itself:-) Good work.
Letter 7 – Charlie Brown Blister Beetle
Found in Albuquerque NM Aug 2010
Location: USA South West
September 8, 2010 2:48 am
I am curious as to the identity of this insect.
Signature: It doesn’t matter.
Dear It doesn’t matter,
The enthusiasm of your email literally oozed off the computer screen at us, so we were compelled to copiously research your identification request until we were successful because we thought it would mean so much to you. The clarity of your low resolution image that appears to have been taken with a cellular telephone seems to indicate a beetle with a soft body, so we started by searching BugGuide for Soldier Beetles, and we drew a blank. We next turned to Blister Beetles on BugGuide and browsed through page after page of BugGuide imagery in the subfamily Nemognathinae without success. We had better luck with the BugGuide section on the subfamily Meloinae where we finally identified the Charlie Brown Blister Beetle, Pyrota palpalis, but alas, BugGuide has no specific information on the species. We sincerely hope that our research has not sated your curiosity, and that we have whetted your appetite to pursue more knowledge on this gaily marked beetle named after a pop culture icon. At any rate, it did whet our appetite, so we tried some additional research in an attempt to learn specifics about the Charlie Brown Blister Beetle. We did find it on the Texas Beetle Information website, but other than a map of Texas indicating the range in the southwest portion of the state and a link to photos on the Harvard Entomology website, there was not much to glean, though we do like the photos of the labels that accompany the type specimen.
Thank you for the research you put towards this query. I was able to find a good picture of one thanks to your assistance.
This is exactly the insect that my fiance took a picture of.
Thank you for you time and efforts!
You’re welcome. We enjoyed doing the research.
Letter 8 – Charlie Brown Blister Beetle, or something closely related.
Location: Hi-Desert, north of Palm Springs
October 24, 2010 11:37 am
I don’t know if this little guy is actually a beetle, but he sure is pretty. Can you please tell me what kind of insect it is?
Signature: Michele Zafico
Your lovely beetle is a Blister Beetle in the genus Pyrota, and BugGuide includes several species that look quite similar to your specimen. It really resembles the Charlie Brown Blister Beetle, Pyrota palpalis, but BugGuide does not report any sightings from California, only Arizona and New Mexico. While the exact species may remain questionable, we are confident with the genus identification, and we love the common name Charlie Brown Blister Beetle.
Letter 9 – Blister Beetle: Pyrota concinna
No Idea what this is
Location: San Juan County New Mexico, USA
August 23, 2011 8:35 am
I have sent you the clearest photo possible. It seems to have a beetle like shell possible wings underneath, a head and neck that slink in and out like that of a slug and an Ant shaped head.
Signature: New bug watcher
Dear New bug watcher,
This is a Blister Beetle in the family Meloidae. We have identified the species as Pyrota concinna based on a few photos posted to BugGuide. This is a new species for our site. You should read up on Blister Beetles in our archive and on BugGuideso that you are aware of any potential dangers that might arise from trying to handle them.
Letter 10 – Blister Beetle: Zonitis or Nemognatha???
Subject: What is this Bug?
Location: Sulphur Oklahoma (we presume)
July 14, 2012
I was just wondering what kind of bug this is.
This is a Blister Beetle in the family Meloidae, and Blister Beetles should be handled with caution (or better yet, not handled), since they release a compound known as cantharidin from their joints that is known to cause blistering of human skin. Thanks to BugGuide, we believe your beetle is in the subfamily Nemognathinae. The closest match we could find was this unidentified species in the genus Zonitis from BugGuide, but we would not discount that it might be in the genus Nemognatha, which has many orange species represented on BugGuide as well. Since you did not submit your request using our standard form, we researched our archives and found this earlier posting from you of a Bumelia Borer from Sulphur Oklahoma, and we are presuming this letter is from the same general location. While we understand it might be easier to just search your email records for our email address, we request that you please use our standard form in the future as there are many fields that assist in our identifications.
Letter 11 – Charlie Brown Blister Beetles
Subject: Orange and back beetle
Location: Apple Valley California, USA
September 9, 2013 12:01 pm
I was bombarded with these guys in a single night in Apple Valley CA. I have never seen one before then all of a sudden there were about 30 on my house. Everyone thinks they are a longhorn species but I cannot find anything that looks exactly like this. Can you please let me know the species, thank you.
Signature: beetle identification
One of the first times we posted a photo of your beetle, Pyrota palpalis, which is commonly called the Charlie Brown Blister Beetle, we were not sure if the species was correct because BugGuide had no sightings in California. That has since changed with this submission to BugGuide. Like other Blister Beetles, you should avoid handling the Charlie Brown Blister Beetle as Blister Beetles might exude a compound cantharadin, that can cause the skin to blister. The Texas Beetle Information page also pictures the Charlie Brown Blister Beetle, but gives no specifics on its life cycle.
Letter 12 – Blister Beetle: Oil Beetle or not??? NOT
Subject: To Beetle or not to Beetle?
Location: Central Oklahoma
September 14, 2013 4:42 pm
Trying desperately to identify this bug. Seems it may be a beetle of some sort, but am unable to find any referenced anywhere. It is solid black with some red markings beneath the two ”wings”. The ”wings” lay flat on the back; the wing on the right is damaged. Found in central Oklahoma this week.
Signature: Okie Bugs
Hi Okie Bugs,
Prior to doing any research, we were convinced that this must be an Oil Beetle, a group of Blister Beetles in the genus Meloe. The only unusual feature is the red markings which we have not seen on an Oil Beetle before. We couldn’t find any examples of Oil Beetles with red markings on BugGuide, so we tried to search other genera of Blister Beetles. We were surprised to find images of Lytta sublaevis on BugGuide, and they look like your beetle, though Lytta sublaevis also has red markings on the head and thorax. Additionally, Lytta sublaevis is only found in California. We can say for certain this is a Blister Beetle, and we strongly suspect it is an Oil Beetle in the genus Meloe, but we cannot guarantee that with any certainty. We will continue to research this matter and we welcome any assistance our readership can provide.
Eric Eaton provides a correction
This is Epicauta conferta:
Letter 13 – Margined Blister Beetle eating tomato leaves
Subject: Bug eating tomato leaves
Location: Northern Shenandoah valley va
August 14, 2014 5:37 pm
This bug is all over out garden in northwestern virginia.
I would like to know what it is.
Signature: “Bugged out” in va
Dear Bugged out in VA,
This is a Margined Blister Beetle, Epicauta funebris, and though BugGuide does not indicate any food preferences, we have received other reports of Margined Blister Beetles feeding on the leaves of tomatoes and other vegetables and ornamental garden plants. In My Kitchen Garden discusses Blister Beetles in organic vegetable gardens.
Letter 14 – Iron Cross Blister Beetles Mating and Eating
Subject: insects near Superstition Mtn. Arizona
Location: Superstition Mountain, AZ
April 13, 2015 5:02 am
I came across these insects on a hiking trail near our house April 12, 2015 , at the base of Superstition Mtn., Arizona. Lots of people hiking were wondering what they were. Their heads and mandibles remind me of an ant and they have 3 pr. of legs. All the insects were feeding on the same flower heads, which had finished flowering and were about to produce seed. I assume they were getting a high energy feed this way.
It seems we get at least one submission each spring asking for an identification of Iron Cross Blister Beetles in the genus Tegrodera. According to BugGuide: “Eriastrum [woollystar] is an important food source for all adults.”
Letter 15 – Charlie Brown Blister Beetle
Subject: Odd beatle like desert insect
Location: High Desert
August 5, 2015 2:23 am
Found this one in my house near Joshua Tree National Park.
Your beetle is Pyrota palpalis, a Blister Beetle in the family Meloidae, and we are not certain what prompted some comic influenced entomologist to bequeath it with an amusing name, but it is commonly called a Charlie Brown Blister Beetle.
Letter 16 – Charlie Brown Blister Beetle
Subject: What’s this bug?
Location: 20 miles north of Deming off Hwy 180
September 6, 2015 10:10 pm
20 miles north of Deming, NM, Sept 6, 2015, 11 pm. Left the porch light on, and got a whole bunch of these, plus 2 Praying Mantis, and some round black beetles. This has been a year of above avg rainfall, extra mice have drawn extra fauna.
Thank you Bugman!
Signature: The Bugman
This is a Charlie Brown Blister Beetle, Pyrota palpalis, and in our opinion, it is one of the best common insect names for a North American insect. The Charlie Brown Blister Beetle is reported from Texas to California according to Bugguide.
Letter 17 – Margined Blister Beetle eating tomato plants
Subject: This bug is eating my tomato plants & I can’t identify after numerous searches
Location: West Tennessee
July 13, 2017 9:27 pm
I’m new to gardening. So far I’ve been able to identify the pests and beneficials in my garden. However, I’ve failed to identify this bug on any garden pest websites or other picture databases of bugs. Please help it appears these guys are eating on my tomato plants and I’d like to find out what they are so I can use natural means of controlling them.
This is a Blister Beetle and we are very confident it is the Margined Blister Beetle, Epicauta funebris, thanks to this image posted to BugGuide. Of the genus, BugGuide notes: “Some species are crop pests.”
Letter 18 – Bug of the Month September 2018: Striped Blister Beetle
Subject: Black and yellow bug
Geographic location of the bug: NE Oklahoma
Time: 08:09 AM EDT
Your letter to the bugman: Hey bugman-
Tgaese are invading myhome. They are everywhere – walls, ceilings counter tops and even floor. It hasn’t bitten or stung any one. . . Yet.
How you want your letter signed: Cyndiluwho
This is a Striped Blister Beetle, Epicauta vittata, and according to BugGuide: “Feeds on variety of plants, especially Solanaceae (e.g., potatoes, tomatoes), also soybeans, other crops. Pigweed, Amaranthus species, not a crop plant, is also fed upon extensively.” This is an outdoor species that occasionally enters homes accidentally, so we don’t know why you are finding so many indoors. According to Featured Creatures: “The adults are most active during the morning and late afternoon, seeking shelter from the sun at mid-day. In particularly hot, arid climates they remain inactive during the day, confining their activity to the evening hours.” That site also notes: “Striped blister beetle is one of the most damaging of the blister beetles to vegetable crops in areas where it occurs. This is due to its feeding preferences, which include several common crops and greater preference for foliage than some other species; its propensity to feed on fruits of solanaceous plants; its relatively large size and voracious appetite; its strong tendency to aggregate into large mating and feeding swarms; and its high degree of dispersiveness, which can result in sudden appearance of large swarms of beetles. … The damage caused by Epicauta spp. blister beetles is offset, at least during periods of relatively low beetle density, by the predatory behavior of blister beetle larvae. Epicauta spp. larvae feed on the eggs of grasshoppers, including many crop-damaging Melanoplus spp. During periods of grasshopper abundance the number of blister beetles tends to increase substantially.” Blister Beetles should be handled with caution since some species are capable of secreting a compound, cantharidin, that is known to cause blistering in sensitive individuals. We have selected your submission as our Bug of the Month for September 2018.