Striped Blister Beetle: Essential Facts and Tips for Gardeners

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Striped blister beetles are a fascinating species of beetle, known for their distinct appearance and unique characteristics. They’re typically tan to amber in color and feature three dark stripes on each wing cover, with a narrow “neck” that contrasts with their broader head and abdomen. These beetles measure about 1/3 to 2/3 inches in length and can often be found in alfalfa fields or other grassy areas. Source

You may have heard that handling blister beetles can cause skin irritation or blisters. This is due to a chemical substance called cantharidin, present in their bodies. It’s important to be cautious when dealing with these insects, as even a mild touch can lead to painful blisters. On the other hand, striped blister beetles play a significant role in the ecosystem, as their larvae feed on other insects, helping control pest populations.

Now that you’ve been introduced to striped blister beetles, you’ll want to learn about their lifecycle, habitat, and the precautions you should take when dealing with them. In this article, we’ll dive deeper into the world of striped blister beetles, equipping you with all the essential knowledge about these fascinating creatures.

What is a Striped Blister Beetle?

A striped blister beetle is an elongated insect that can be easily identified by its unique appearance. The body of this beetle is typically tan to amber-colored with three distinct black stripes on each wing cover (elytron), giving it a striking design. The striped blister beetle belongs to the family Meloidae and is scientifically known as Epicauta vittata.

In terms of size, these insects generally range from 1/3 to 2/3 inches long, with a narrow thorax that contrasts with their broader head and abdomen. Their antenna is straight, making up about one-third of their total body length. Here are some of their key features:

  • Tan to amber-colored body
  • Three black stripes on each wing cover
  • Elongated shape with a narrow thorax
  • Straight antennae

Striped blister beetles can sometimes be found feeding on cultivated plants, such as alfalfa, beet, potato, and tomato, possibly causing defoliation due to their gregarious behavior. Furthermore, despite their relatively small size, these beetles are known for their ability to produce a toxic compound called cantharidin, which can cause skin irritation or blistering in humans and be harmful to animals if consumed.

So, you now have a better understanding of what a striped blister beetle is, including its appearance, size, and some key features. Keep in mind the potential harm they can cause and be cautious when handling them if you happen to encounter one in your garden or field.

Striped Blister Beetle Lifecycle

The striped blister beetle goes through a fascinating lifecycle, consisting of various stages such as eggs, larvae, pupae, and finally adult beetles. Let’s have a closer look at these crucial stages in the life of a striped blister beetle.

Eggs: In the beginning, the female beetles lay their eggs in clusters in the soil, typically during the warm months of the year. Hollows in the ground are preferable locations for egg-laying to ensure safe and optimal conditions for unhatched larvae.

Larval stages: The larvae hatch from the eggs after about 10 days and emerge with a fierce appetite, ready to feed on grasshopper eggs, which are their primary food source. Striped blister beetle larvae go through several instar stages, molting each time to accommodate their growing size. The first instar is known as the “triungulin” stage, marked by their tiny, active, and long-legged appearance.

Pupa: After completing all the larval instar stages, the striped blister beetle undergoes pupation in the soil, a process similar to metamorphosis. During pupation, the larvae transform into adult striped blister beetles, featuring the familiar narrow neck and distinct black stripes on their amber-colored wing covers.

Adult beetles: Once the transformation is complete, the adult striped blister beetles emerge and start to feed on plants, such as alfalfa, while also seeking mates to reproduce. They are particularly active from mid-May to October, with their peak concentration in June and July.

To summarize, the striped blister beetle lifecycle consists of the following stages:

  • Egg-laying in clusters in the soil
  • Multiple larval stages, feeding on grasshopper eggs
  • Pupation in the soil, transforming from larva to adult beetle
  • Emergence as an adult beetle, feeding on plants and seeking mates for reproduction

Understanding the striped blister beetle lifecycle is essential for managing their populations, as they can pose threats to plants and even livestock when ingested in large numbers. By knowing their habits and lifecycle, it’s possible to mitigate any potential damages caused by these fascinating insects.

Habitat and Distribution

Striped blister beetles are insects commonly found in various parts of the United States, especially in Oklahoma. They typically emerge after the first cutting of alfalfa in late April or early May. These beetles are active from mid-May to October, with their peak activity in June and July.

You’ll find them feeding on foliage and blooms in alfalfa hay fields. They’re also attracted to broadleaf weeds and other plants blooming near alfalfa fields or in grass pastures. These beetles can cause minimal feeding damage, but it’s important to keep an eye out for them.

Here are some key features of striped blister beetles:

  • Distinctive narrow “neck” contrasting with the broader head and abdomen
  • Cylindrical body shape
  • Tan to amber colored body with three dark (black) stripes on each wing cover

By understanding their habitat and distribution, you can better manage these beetles and protect your plants. Keep the surroundings free from broadleaf weeds and that they prefer, and monitor your alfalfa fields regularly during their active season.

Feeding Habits

Striped blister beetles feed on a variety of plants and are known to cause damage to many crops. They prefer leaves and flowers of popular crops like alfalfa, but will also feed on pea, potato, bean, soybean, eggplant, tomato, pepper, corn, radish, spinach, and clover. They are particularly attracted to certain vegetables, especially when blossoms are present.

These beetles also have an indirect but important relationship with grasshoppers. In the late spring and early summer, blister beetles feed on grasshopper eggs, which helps limit grasshopper populations. This can benefit farmers, as grasshoppers can be highly damaging to their crops.

To sum up, striped blister beetles primarily feed on:

  • Leaves and flowers of various crops
  • Alfalfa, especially when flowering
  • Other vegetables including tomatoes, peppers, and eggplants
  • Grasshopper eggs in the late spring and early summer

Remember, it’s essential to monitor your crops for signs of damage caused by blister beetles and take appropriate measures to control their population when necessary.

Striped Blister Beetle and Agriculture

The striped blister beetle is a common pest in agriculture. This insect is known for attacking various crops, such as alfalfa, potatoes, and tomatoes. They can cause significant damage to your alfalfa fields and other crops.

These beetles are usually active around mid-June or later. Their emergence typically occurs after the first cutting of alfalfa. The striped blister beetles are gregarious, which means they travel and feed in groups. This behavior can lead to locally catastrophic damage to your crops, particularly alfalfa hay or alfalfa fields.

It is essential to manage these pests to protect your crops. One method involves using chemical insecticides, like pyrethroids, which can help control blister beetle populations. However, bear in mind there might be a pre-harvest waiting period when using such chemicals.

  • Pros:
    • Effective in controlling blister beetles
    • Protects crops from damage
  • Cons:
    • Use of chemicals on your crops
    • Pre-harvest waiting period

Implementing proper management practices, such as monitoring your crops for signs of insect infestations, can also minimize the damage caused by striped blister beetles. Moreover, understanding the life cycles and behaviors of these pests will help you stay one step ahead in shielding your crops.

Health Hazards of Striped Blister Beetle

Striped blister beetles (Epicauta vittata) are known for producing the toxic chemical called cantharidin. This substance is hazardous and can cause serious problems when these beetles come into contact with humans, animals, or crops.

When striped blister beetles are crushed on the skin, cantharidin may cause skin irritation, blisters, and swelling. In some cases, it can even lead to sweating and eye irritation. It is crucial to avoid handling these insects directly.

Besides human exposure, striped blister beetles pose a significant threat to livestock, particularly horses. Horses may ingest these beetles while feeding on contaminated hay or forage. Ingestion of even minimal amounts of cantharidin can lead to blister beetle poisoning, which causes symptoms like colic, fever, depression, lethargy, and diarrhea. In worst cases, ingestion of these beetles can be fatal for horses.

To reduce the risk of exposure to cantharidin from striped blister beetles, it’s essential to implement control measures for these insects. Some steps include timely harvesting of forage crops, regular inspection of hay for beetle presence, and proper storage of hay to minimize the chances of beetle contamination.

Here’s a quick comparison of the impact of striped blister beetles on humans and animals:

Affects Symptoms Consequences Control Measures
Humans Skin irritation, blisters, swelling, eye irritation Discomfort, pain Avoid handling, apply protective gloves if needed
Horses, Livestock Colic, fever, depression, lethargy, diarrhea Possible death Timely harvesting, inspect hay, proper storage

In conclusion, you should be cautious of the striped blister beetle’s toxic cantharidin compound and take necessary precautions to prevent skin irritation or livestock loss.

Prevention and Control of Striped Blister Beetle

To prevent striped blister beetles from infesting your plants, early detection is crucial. Look for their unique characteristics:

  • Long, cylindrical body
  • Length of 3/4 to 2 cm
  • Alternating yellow and black stripes

To effectively manage these beetles in your garden or farm, consider the following approaches:

Identifying and Monitoring

Stay informed about the emergence of adult blister beetles. Generally, their activity increases in mid-June after the first cutting of alfalfa.

Cultural Control

Use mechanical methods, such as crimpers, to kill beetles without using chemicals. This will minimize their impact on your plants and the environment.

Chemical Control

If you need a more aggressive solution, consider using insecticides. Before applying any chemicals, consult your local extension office for advice on the most effective and safest products for your specific situation.

Pros and Cons of Chemical Control


  • Effective in reducing beetle populations
  • Quick results


  • Risk of environmental contamination
  • Potential harm to beneficial insects

Comparison Table: Cultural vs. Chemical Control

  Cultural Control Chemical Control
Effectiveness Moderate High
Environmentally Friendly Yes No
Potential Side Effects None Harm to beneficial insects

Remember that each strategy comes with its own set of advantages and drawbacks. Choose the one that best fits your specific needs and environment. By taking these steps to prevent and control striped blister beetles, you can protect your plants and ensure a healthy growing environment.

Bug Control Recommendation Tool

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Are you willing to monitor and maintain the treatment yourself?

Chemical Properties and Uses of Cantharidin

Cantharidin is a toxic trycyclic monoterpene found in blister beetles like the striped blister beetle 1. This compound has a variety of uses and effects, due to its unique properties. Let’s explore some of them:


Cantharidin is highly poisonous, serving as a chemical defense against predators 2. Be cautious when handling these beetles, as their toxic hemolymph can cause blistering dermatosis upon contact with the skin 3.


Historically, cantharidin was believed to be a sexual stimulant and used as an aphrodisiac, often called “Spanish fly” 1. However, its usage in this context is dangerous and not recommended due to its toxic nature.

Antiparasitic Properties

Cantharidin also exhibits antiparasitic properties, offering potential for medical research and treatments 2. The mechanism of action is still under investigation, and its uses continue to be explored.

In conclusion, cantharidin is a remarkable compound found in the striped blister beetle, with both benefits and risks associated with its usage. Always exercise caution when handling these beetles and their secretions, and be aware of the potential applications of this fascinating, yet dangerous, chemical.

Striped Blister Beetle’s Impact on Animals and Livestock

Striped blister beetles pose a serious threat to animals, especially livestock like horses. When ingested, the beetles release a toxic substance called cantharidin, which causes poisoning in animals.

Horses are particularly susceptible to blister beetle poisoning. Even ingesting just 30 to 50 blister beetles can be lethal to a horse. The symptoms of blister beetle poisoning in horses include colic, pain, small intestine and bladder damage, depression, and shock. If your horse displays these symptoms, consult a veterinarian immediately.

Blister beetles tend to thrive in alfalfa fields, increasing the risk of poisoning if these beetles find their way into alfalfa hay. Adult beetles emerge and become active in the later part of the season, typically after the first cutting of alfalfa.

Other livestock, such as cows and sheep, may also be affected, albeit to a lesser extent. While the focus is on animals that consume alfalfa and alfalfa hay, it’s still crucial to monitor the presence of these beetles around other agricultural crops like bean and soybean fields to reduce the likelihood of poisoning.

To protect your animals from blister beetles, implement the following preventative measures:

  • Regularly inspect hay for the presence of dead beetles before feeding it to your animals.
  • Avoid purchasing alfalfa hay with a high concentration of crushed beetles.
  • Cut alfalfa early in the season, as most beetles become active later.
  • Be mindful of surrounding crops and weeds that may attract blister beetles, such as blooming canola and broadleaf weeds.

In conclusion, striped blister beetles are harmful to animals, primarily horses and other livestock. Keep a close eye on alfalfa hay, inspect it for the presence of beetles, and take precautionary measures to protect your animals’ health.

Interesting Facts about Striped Blister Beetle

The striped blister beetle belongs to the family Meloidae and is classified as Epicauta funebris. Here are some interesting facts about these beetles:

One characteristic of striped blister beetles is their narrow “neck,” which sets them apart from other beetles with broader heads and abdomens. They have tan to amber-colored bodies and display three dark stripes on each wing cover. These insects usually measure between 1/3 to 2/3 inches long. Source

In some cases, these beetles can be beneficial. For instance, their larvae are known to feed on grasshopper eggs, which helps in controlling grasshopper populations. However, their swarms can be a concern for alfalfa growers, as the beetles may congregate in high numbers during June and July. Source

Another closely related species is the margined blister beetle, which shares some features with the striped blister beetle but maintains a distinctive appearance. Typically found in the southeastern United States, margined blister beetles belong to the same Meloidae family.

Striped blister beetles become most active after the first cutting of alfalfa, which usually occurs in late April or early May. Their emergence has not been observed earlier than May 14 in Oklahoma, though activity may begin as late as mid-June. Source

When discussing striped blister beetles, it is crucial to mention the toxic compound Cantharidin found in their bodies. This substance can be dangerous when ingested by livestock, such as horses and cattle, and may even lead to fatalities. That’s why it’s essential to monitor for their presence in hay fields and pastures. Source

In summary, striped blister beetles exhibit distinct features and can be both beneficial and problematic, depending on the context. Always remain vigilant when dealing with these fascinating creatures, especially when it comes to protecting your livestock.


  1. Antiparasitic Properties of Cantharidin and the Blister Beetle 2
  2. Antiparasitic Properties of Cantharidin and the Blister Beetle: More Information 2
  3. Cantharidin Revisited: A Blistering Defense of an Ancient Medicine

Reader Emails

Over the years, our website, has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – Striped Blister Beetle


I certainly hope I am not becoming a pest. I walked out this morning and found hundres of these bugs in groups all over our yard. I have scoured your site and can’t find anything similar with the horizontal stripes. They weren’t there yesterday, but they are certainly there today! Thanks again,
Sandy, NE Arkanas

Hi Sandy,
You couldn’t locate the Striped Blister Beetle, Epicauta vittata, on our site, because until now, we didn’t have one. It is a great image. We are currently having difficulty posting and are awaiting assistance from our web master, but we will soon post your photo and letter.

Letter 2 – Striped Blister Beetle


What bug is this
August 20, 2009
i have a bunch of these bugs in my yard and i want to know what they are
Duncan Oklahoma
Dear Michael,
This is a Striped Blister Beetle, Epicauta vittata.  According to BugGuide it:  “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.”  It is also called an Old Fashioned Potato Bug.

Letter 3 – Striped Blister Beetle


Subject: Striped Blister Bug or something else?
Location: Greenleaf, WI
July 4, 2012 12:42 pm
Seems each year my garden shows me a new bug. Last year was the invastion of squash bugs, this year the attached mystery bug, photo taken today, July 4th. Doing some searching, I’m thinking it may be a striped blister bug, but not sure. Similar images I’ve found don’t include Wisconsin as their zone, so that’s what makes me unsure of the identification. Seems to be eating my potato plants, but if it is a blister bug, I don’t know how much I want to handle them to attempt to pick them off like I usually handle potato bugs. Otherwise, what might help discourage their presence?
Signature: J Schmidt

Striped Blister Beetles

Dear J Schmidt,
First we want to commend you on identifying your Striped Blister Beetles,
Epicauta vittata, but we would like to point out that they are beetles, not true bugs.  You can read more about them on BugGuide, which lists an alternate common name, Old-Fashioned Potato Bug, which supports your observation that they are eating your potato plant leaves.  Also it is worth noting that BugGuide has reports from Wisconsin.  In the lower left corner of your photo is a grasshopper, and grasshoppers feed on leaves as well.  Many Blister Beetles feed on the eggs of grasshoppers as larvae, so Blister Beetles help keep the grasshopper population in check.  You might have a bigger problem if you eliminate the Striped Blister Beetles. 

Letter 4 – Striped Blister Beetles


Subject: Black and orange bugs
Location: Southwest Missouri
July 10, 2012 11:02 am
I am in Southwest Missouri. I’ve had these bugs in my garden destroying plants and vegetables for about 2 months now. They started with some of the weeds, but when I pulled the weeds to keep the seeds from dropping into the garden, they moved on to the spinach. After destroying all my spinach, they have now moved on to my tomatoes. They were only eating a few over ripe tomatoes, now they are even starting on the green ones! They seem to swarm in an area at a time (there must be several hundred to a thousand when they swarm)
I’ve done all sorts of research and just can’t seem to find a picture or any info online.
They have dark orange heads, black legs, small pinchers and black or dark brown bodies with orange stripes running the length of their wings/bodies.
Sorry for the quality of the pics. I’ve got some of them in a plastic bag.
Do you have any idea what they are and how to get rid of them? (Preferably using an organic solution)
Signature: -Kris

Striped Blister Beetles

Hi Kris,
We recently posted this letter from nearby Wisconsin of Striped Blister Beetles, also called the Old Fashioned Potato Bug.  You should not handle the Striped Blister Beetles because many members of the family secrete a compound known as cantharidin that can cause skin to blister.  We do not give extermination advice.  See BugGuide for additional information. 

Letter 5 – Striped Blister Beetle


Subject: what kind of bug is this ?
Location: Telferner Texas
April 23, 2013 8:24 am
I found this bug at work and have never seen one before i would like to know what it is.
Signature: Kimberly wright

Striped Blister Beetle
Striped Blister Beetle

Dear Kimberly,
This is a Striped Blister Beetle, Epicauta vittata.  According to the Featured Creatures website:  “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. It also has been implicated in the transmission of bean pod mottle virus to soybean.”  Like other members of the Blister Beetle family, the Striped Blister Beetle should not be handled as it can release a substance, cantharidin, that is know to cause blistering in human skin.


Letter 6 – Striped Blister Beetle


Subject:  Tomato eating insects
Geographic location of the bug:  Alvord. Texas
Date: 08/03/2018
Time: 10:13 AM EDT
Your letter to the bugman:  This morning i found hindreds of these bugs. When i watered the tomatoes they fled like cockroaches in the light. What are these tomato eating beasts?
How you want your letter signed:  Thank you

Striped Blister Beetles

This is most likely a Striped Blister Beetle, Epicauta vittata, which is pictured on BugGuide, but there are also several very similar looking members of the same genus.  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.”


  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

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3 Comments. Leave new

  • Crystal Books
    July 7, 2012 12:44 am

    I just moved in to a brand new house a week ago today and have tons of them crawling around the front of my house a now in my garage.I have small children. Can you please tell me the best way to get rid of them!!

    • We can only read the first few words of you comment so we don’t know if you have a question. Sorry about the technical difficulty.

  • I have a beetle with a hard case that has horizontal white stripes the length of a 3/4″ body. The stripes are not continuous across the back but have a small black line connecting the two sides


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