The claim
There are currently repeated warnings about the oil beetle on social media, claiming that it is poisonous to people and animals!
Our conclusion
Oil beetles can pose a potential danger to both humans and animals due to their cantharidin content. However, by taking appropriate precautions and avoiding direct contact, unpleasant encounters can be avoided.
Oil beetles, members of the genus Meloe, are insects common in many parts of the world. Although they are known for their striking colors and distinctive shapes, what is less known is that they can also be poisonous.
Oil beetles are easily recognized by their squat bodies and short elytra that do not completely cover the abdominal segments. These insects feed on plants and are usually found in meadows and fields. A notable feature of oil beetles is their ability to secrete a chemical called cantharidin when they feel threatened.
Toxicity of cantharidin
Cantharidin is a potent poison that can cause irritation and inflammation when it comes into contact with skin, mucous membranes or internal organs. People and animals can accidentally come into contact with cantharidin by touching or crushing an oil beetle. The consequences can range from mild skin irritation to severe chemical burns and blistering. If cantharidin is swallowed or inhaled, severe symptoms of poisoning such as nausea, vomiting, diarrhea and, in extreme cases, even kidney failure or death can occur.
Note: The German Wildlife Foundation strongly emphasizes the dangers associated with the purple or black-blue oil beetle, also known as the May worm. The reason for this is that this oil beetle contains the poison cantharidin. When threatened, it secretes a yellowish fluid from its leg joints that contains this poison (hence the name).
Precautions for people
Although oil beetles generally do not pose an immediate threat to humans, it is advisable to avoid direct skin contact with these insects. If you spot an oil beetle, you should not touch it with your bare hands. In the event of exposure to cantharidin, it is important to immediately wash the affected area thoroughly with soap and water and seek medical attention if symptoms persist.
Risks for animals
Animals, particularly grazing animals such as horses and cattle, can suffer cantharidin poisoning from eating oil beetles or contaminated feed. It is important that farmers and livestock producers monitor their pastures to minimize animal contact with oil beetles.
Fact check: The truth about oil beetles and their toxicity
Fact 1: Cantharidin is harmless to humans and animals.
❌ Wrong: Cantharidin is a strong poison that can cause irritation and inflammation when it comes into contact with skin, mucous membranes or internal organs. In severe cases, cantharidin poisoning can lead to kidney failure or even death. It is difficult to say how many grams of poison pose a risk to humans when it comes to the poisonous oil beetle. This depends on many factors, such as the age, health, height and weight of the person affected, and the type and amount of poison that was ingested. The LD50 for an adult human is 0.05 mg per kg body weight
Fact 2: Oil beetles are known for their striking colors and distinctive shapes.
✅ Correct: Oil beetles are easy to recognize by their squat bodies and short elytra, which do not completely cover their abdominal segments.
Fact 3: Oil beetles secrete cantharidin when they feel threatened.
✅ Correct: Cantharidin is a potent chemical substance secreted by oil beetles to ward off predators.
Fact 4: Grazing animals can suffer cantharidin poisoning from eating oil beetles or contaminated feed.
✅ Correct: Animals such as horses and cattle can suffer symptoms of poisoning from eating oil beetles or food contaminated with cantharidin. It is therefore important that farmers and livestock owners monitor their pastures.
Fact 5: Direct skin contact with oil beetles should be avoided.
✅ Correct: To avoid skin irritation or worse, direct skin contact with oil beetles should be avoided.
Fact 6: Cantharidin is not used in medicine.
❌ False: Cantharidin actually has some medical uses, including treating warts and skin diseases. Researchers are also studying the potential applications of cantharidin in cancer therapy. Nevertheless, cantharidin should only be used under strict medical supervision and in controlled doses.
Fact 7: Invasive oil beetle species can endanger native plants and animals.
✅ Correct: In some regions there is concern that invasive oil beetle species could damage native plants and animals. Environmentalists and authorities must be vigilant to monitor the spread of invasive oil beetle species and take control measures if necessary.
Fact 8: Oil beetles are protected species in many parts of the world.
✅ Correct: In some countries and regions, oil beetles are protected species in order to maintain their populations and protect biological diversity. It is important to know and comply with oil beetle protection laws and regulations in your country or region.
Fact 9: Cantharidin can also occur in other insect species.
✅ Correct: Although oil beetles are the best-known producers of cantharidin, this substance is also found in some other insect species, particularly in other members of the blister beetle family.
Fact 10: Oil beetles play an important role in the ecosystem.
✅ Correct: Oil beetles are an important part of the ecosystem as they are both herbivores and prey for other animals. They are also important pollinators for some plant species.
Conclusion: Oil beetles are a fascinating but potentially dangerous group of insects that can affect both humans and animals. Through education, research and collaboration, we can ensure we minimize risks while valuing and protecting the diversity and beauty of our natural environment.
Sources:
- German Wildlife Foundation
- NABU
- Poison Information Center Erfurt
- Austrian Nature Conservation Association
- Frankfurter Neue Presse
Also read:
- Fact check: Are potatoes with shoots or green spots still edible?
- Fact check: cutting boards and bacteria
Article image: Black-blue oil beetle (Meloe proscarabaeus), also known as black May worm. Photographer: ArtMechanic , License: ( CC BY-SA 3.0 )
If you enjoyed this post and value the importance of well-founded information, become part of the exclusive Mimikama Club! Support our work and help us promote awareness and combat misinformation. As a club member you receive:
📬 Special Weekly Newsletter: Get exclusive content straight to your inbox.
🎥 Exclusive video* “Fact Checker Basic Course”: Learn from Andre Wolf how to recognize and combat misinformation.
📅 Early access to in-depth articles and fact checks: always be one step ahead.
📄 Bonus articles, just for you: Discover content you won't find anywhere else.
📝 Participation in webinars and workshops : Join us live or watch the recordings.
✔️ Quality exchange: Discuss safely in our comment function without trolls and bots.
Join us and become part of a community that stands for truth and clarity. Together we can make the world a little better!
* In this special course, Andre Wolf will teach you how to recognize and effectively combat misinformation. After completing the video, you have the opportunity to join our research team and actively participate in the education - an opportunity that is exclusively reserved for our club members!
Notes:
1) This content reflects the current state of affairs at the time of publication. The reproduction of individual images, screenshots, embeds or video sequences serves to discuss the topic. 2) Individual contributions were created through the use of machine assistance and were carefully checked by the Mimikama editorial team before publication. ( Reason )

