Venom, burns and paralysis: Denmark's most dangerous wildlife

Elizabeth Anne Brown
Elizabeth Anne Brown - [email protected]
Venom, burns and paralysis: Denmark's most dangerous wildlife
Female horse and cleg flies need a blood meal to lay their eggs. Photo: Botaurus, Wikimedia.

Newcomers often expect Danish flora and fauna to be mild-mannered – especially those of us who move to the Nordic countries from more tropical climes. We’ve rounded up a list of creatures (and one plant) to keep an eye out for.


European hornet, Vespa crabro. The European hornet, which can reach sizes up to 35 mm or 1.4 inches, is known to drift through open windows at night. Photo: Judy Gallagher/Flickr.

European hornet

One of the most alarming Danish creatures makes house calls.  The European hornet, Denmark’s largest wasp at 2.5-3.5 cm or 1-1.4 inches in length, is known to drift through open windows on a warm summer night with all the stealth and grace of a rogue apache helicopter. You’ll likely hear it before you see it.

Despite its distressing size, no, it’s not a murder hornet. And unlike its semi-demonic cousin the yellowjacket, the European hornet isn’t aggressive unless its nest is disturbed (get professional help to remove a nest), though it will sting if handled. The European hornet’s sting is more painful than a bee sting, and since hornets don’t lose their stingers a single individual can jab repeatedly.




Common horse fly

Female horse and cleg flies need a blood meal to lay their eggs. Photo: Botaurus, Wikimedia.

Horse and cleg flies

Horse and cleg flies look like beefy houseflies – but like mosquitos, the females suck blood in order to lay their eggs. If a mosquitos’ proboscis is a hypodermic needle, the horse fly breaks the skin with dull serrated scissors, leaving a painful red welt behind. Horse and cleg fly bites are usually no cause for concern. 


Common European adder

This common European adder, with its distinctive zig-zag pattern, is basking in the sun and minding its own business. Photo: Peter von Bagh/Flickr.

Common European adder (or viper)

Denmark’s only venomous snake, the common European adder, typically avoids humans but will bite if handled. It’s important to seek treatment immediately. About 200 Danes a year are bitten, but only 10 percent require hospitalization after initial treatment, according to the Statens Serum Institut. The European viper is protected by Danish law, so if you find one living too close for comfort reach out to the Danish Nature Agency for help with removal.  



Greater weever fish

The greater weever fish delivers a potent toxin through spines in its back. Photo: Guy Paz/Public Domain.

Weever fish

The greater weever fish is the scourge of the Danish coast. It’s an invasive species that lurks on the bottom of shallow waters in the summer. Sharp spines on the weever’s back deliver an extraordinarily painful toxin, and most encounters with humans occur when a weever is unintentionally stepped on (though even a dead weaver can land a sting). According to the Bispebjerg Hospital, weever stings are rarely serious but are characterized by discoloration, radiating pain, dizziness, headaches and for up to 24 hours. Swelling can persist for several months.

Call the Danish poison line at 82 12 12 12 for advice if stung by a weever fish.




Ticks are "the most dangerous animal in Denmark," according to health officials. Photo: Bartłomiej Bulicz, Wikimedia Commons.

Wood tick

According to the Danish Nature Agency, the wood tick is the most dangerous animal in Denmark. Ticks can carry the borrelia bacteria, which can cause Lyme disease if left untreated. The Statens Serum Institut, Denmark’s infectious disease agency, says that about 180 Danes a year are diagnosed with neuroborreliosis, an infection of the brain by the borrelia bacteria. Symptoms include headache, stiffness of the back and neck, and nerve pain or muscle paralysis, typically in the face. Borrelia infections identified early can be treated easily with a course of antibiotics.

Check yourself and loved ones for ticks after time spent outside, and be certain to remove any ticks you find properly.





Contact with giant hogweed can cause severe burns and a long-term sensitivity to sunlight. Photo: Rob Hille, Wikimedia Commons.

 Giant bear claw, or giant hogweed

Kæmpebjørneklo, or ‘giant bear claw,’ is an invasive plant that secretes a sap that makes skin extremely sensitive to sunlight and can cause severe burns, according to the Danish Environmental Protection Agency (Miljøstyrelsen). While the sap doesn’t hurt when it touches the skin initially, it can make the affected area sensitive to sunlight for years.

Giant bear claw is a tall plant topped with white flowers, growing 2-5 meters high. Its stalk is green with red-brown spots and white hairs.

The Danish EPA recommends washing skin that might have had contact with sap using soap and water within 20 minutes. Avoid sunlight for at least 48 hours and ask a doctor about additional measures.


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