Red Headed Blister Beetle: Essential Facts Explained

The red-headed blister beetle (Epicauta hirticornis) is a fascinating insect with some unique characteristics.

This beetle can be identified by its striking red head, soft elongated body, and the cantharidin toxin it produces.

The cantharidin in their body fluids can cause blisters on human skin if mishandled, and even life-threatening inflammations in horses and livestock.

Red Headed Blister Beetle
Master Blister Beetle

These beetles can be found in various parts of the United States and Canada, with their population generally peaking around mid-summer.

They are often found in flowering alfalfa hay and their presence is sometimes correlated with grasshopper populations.

While the red-headed blister beetle is not the only species of its kind, it offers a fascinating glimpse into the world of blister beetles and their impacts on agriculture and livestock.

Red Headed Blister Beetle: Identification and Characteristics

Appearance

The Red Headed Blister Beetle, also known as the Master Blister Beetle (Lytta magister), is a member of the Meloidae family, common in North America, particularly in the Southwest. This beetle is characterized by:

  • A bright red head
  • Black or dark-colored body and wings
  • Long legs
  • Thread-like antennae

The body shape of Red Headed Blister Beetles is distinct, with a narrow thorax and wider head, as well as soft, leathery bodies1.

Family Meloidae

Blister beetles belong to the family Meloidae and are known for their ability to produce blisters on contact with human skin due to their hemolymph2.

Master Blister Beetle

They can be found in various colors, sizes, and body shapes. Some common features include:

  • Soft bodies
  • Leathery wings
  • Beaded, thread-like antennae

Life Cycle and Reproduction

Egg to Larvae

  • Female blister beetles lay eggs in soil
  • Eggs hatch within 7-10 days

The journey of a red-headed blister beetle starts as an egg.

Female beetles lay these eggs in shallow soil cavities during the summer. Once an egg is laid, it remains for 7 to 10 days before hatching into a larva.

Larval Stage and Parasites

  • Larvae are parasites to grasshopper eggs
  • Go through several stages of development

In the larval stage, the young blister beetle is parasitic to grasshopper eggs and feeds on them.

As they grow, larvae transition through several stages of development known as instars.

These developmental stages allow the larva to grow and prepare for its eventual transformation into an adult beetle.

Master Blister Beetle

Adult Stage and Mating

  • Attracted to flowers for food
  • Mating occurs in adult stage

Once the beetle reaches its adult stage, it abandons its parasitic lifestyle and becomes attracted to flowers for food.

Adult beetles participate in mating to ensure the continuation of their species.

Comparison Table

Lifecycle StageCharacteristics
EggLaid in soil
LarvaeParasitic to grasshopper eggs
AdultAttracted to flowers, mates

Habitats and Feeding Habits

Host Plants

Red-headed blister beetles feed on a variety of host plants, such as:

  • Alfalfa
  • Potato
  • Tomato

These insects are also known to consume grasshoppers, weeds, and vegetables1.

Floral Preferences

Blister beetles have a specific preference for flowers. They tend to be attracted to:

  • Legumes
  • Shrub blossoms
  • Nectar-rich flowers

Notable examples include beet and Sonoran desert flowers2.

Regional Presence

Red-headed blister beetles are found in various regions, including:

  • Florida
  • Texas
  • Canada
RegionPresence
FloridaHigh
TexasMedium
CanadaLow

Each region has its unique habitat characteristics that influence the beetle’s distribution.

Blister Beetle

Impact on Agriculture and Gardens

Crop Damage

Red-headed blister beetles, along with striped and margined blister beetles, can cause considerable damage to crops.

They feed on various plants such as alfalfa, pigweed, and legumes. These pests may defoliate crops, impacting their growth and yield.

Livestock Health

Blister beetles are a major concern for livestock, particularly horses, due to the presence of a toxic substance called cantharidin in their bodies.

When ingested by animals, blister beetles can cause serious health issues or even death. As reported by NDSU Extension, the ingestion of 25 to 300 beetles can be lethal to an average-sized adult horse.

Livestock health risks with blister beetles:

  • Horses: highly susceptible to blister beetle poisoning
  • Sheep and cows: less susceptible, but still at risk

Garden Pest Management

Managing red-headed blister beetles in gardens can be challenging. Some methods to control their population include:

  • Physical removal: Hand-picking and removing beetles from plants
  • Natural predators: Encouraging birds and other predators in your garden to reduce beetle numbers
  • Chemical control: Using insecticides when needed, but being cautious not to harm beneficial insects
MethodProsCons
Physical removalChemical-free; immediateTime-consuming; not suitable for large infestations
Natural predatorsEnvironmentally friendlyMay not be effective for heavy infestations; dependent on presence of predators
Chemical controlEffective for large infestationsCan harm beneficial insects; may impact the environment

Toxicity and Cantharidin

Direct Contact

When in direct contact with a red-headed blister beetle, cantharidin can cause skin irritation and blisters. A few symptoms include:

  • Pain: The skin can become painful to touch upon contact with a beetle.
  • Welts: Raised, red welts may form on the skin after being in contact with a beetle.
  • Blisters: Cantharidin-induced blisters may develop over time.

Blister Beetle

Symptoms and Treatment

Exposure to the red-headed blister beetle, Lytta magister, may cause symptoms such as:

  • Sweating
  • Swelling
  • Lesions

Upon contact with these beetles, it’s crucial to wash the affected area with soap and water to minimize symptoms.

If you experience eye irritation, consult an eye doctor to evaluate possible damage. In some cases, antibiotics may be necessary to treat skin infections or lesions.

Conclusion

The red-headed blister beetle, with its distinctive appearance and potent toxin, plays a unique role in North American ecosystems.

Found across the United States and Canada, these beetles have a life cycle that intertwines with grasshoppers and impacts agriculture.

While they pose risks to crops and livestock, especially horses, understanding their habits and life cycle can aid in effective management.

From their vibrant colors to their toxic nature, these beetles truly offer a glimpse into the intricate world of insects.

Footnotes

  1. Blister Beetles: Life Cycle & Identification 2

  2. Blister Beetles 2

  3. Blister Beetle Management in Forages and Field Crops

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about red headed blister beetles. Scroll down to have a look at some of them.

Letter 1 – Red Headed Blister Beetle from Malaysia

Subject: Black insect with red head
Location: Penang, Malaysia
June 5, 2016 5:22 am
I came across this bug when I was collecting bugs for a school project at a forest trail near a dam. This insect is black with a red head and has long-ish antennas and legs. Its legs and antennas look sectioned, like bamboo.

It can fly and bite(has wings and pinchers). I fed it some fruit peel and cooked rice and it seems to be eating the rice. Please help me identify the insect.
Signature: Desperate student

Blister Beetle
Red Headed Blister Beetle

Dear Desperate Student,
We immediately recognized your insect as a Blister Beetle in the family Meloidae, and upon searching for the family in Malaysia, we found images of your species on FlickR, but they are not identified to the species level. 

We believe we have successfully identified it as Epicauta hirticornis thanks to an image of a mating pair on Sinobug.  According to Farangs Gone Wild, it is commonly called the Red Headed Blister Beetle.  Blister Beetles should be handled with extreme caution as they can secrete a compound cantharidin that may cause blistering in human skin.

Authors

    by
  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com 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.

  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

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