In parts of Europe, Asian predation is spreading at a furious pace. The velvet thing is big like a bonfire thing and beats out the hive communities.

Along the Finnish border, hunters chase away the marten dog implanted by Josef Stalin. The animal is a threat to the Swedish bird population and carries viral diseases and parasites.

Common to these animals is that they belong to invasive animal species that may be able to displace other native organisms.

- They are sneaky for two reasons. The first is that they come to an environment where they lack natural enemies. The second is that existing animals are not adapted to them, says Mikael Svensson.

Shoved over the seas

Mikael Svensson says that the import of animals and plants in Europe, which usually live in other parts of the world, has increased significantly in recent decades.

Global trade is identified as a major drawback in this context. Aquatic animals cross the seas in the ship's ballast water and insects hide in the cargo.

But even the deliberate release of pets is a source of the problem.

- You may have acquired aquarium fish or a water turtle, then you get tired of having them at home. Instead of killing them, they are released into the wild, without understanding what damage is being done to the ecosystem.

Warmer climates favor invaders

Since then, a third aspect has been added that facilitates establishment - climate change.

- Many southern species died earlier during our winters, but as the climate gets warmer the risk of them succeeding.

- 20 years ago, the winters were so cold in the north that the dog died of starvation. Now it can easily migrate over to Norway.

Once the invaders have spread in the wild, there is usually no return.

- Therefore, it is important to have a good warning system and prompt action when the accident has occurred. Otherwise it can be very expensive and in some cases impossible to fight the problem species.

Velvet Wasp. Eats other wasps and honey bees, which affects pollination of flowering plants. Scientists suspect that a single queen was brought to Europe in the cargo of a ship in the early 2000s. Now the species is widespread in Germany, the Netherlands and the United Kingdom. Photo: Wikimedia Commons: Siga - Own work, CC BY-SA 3.0

Chinese wool hand crab. One of the world's most invasive species with natural distribution in Asia. The wool hand crab has been found in Swedish ports, rivers and lakes several times over the years. Since it is not yet able to spread in Sweden, it is likely to be returned here in the ship's ballast water. Source: Swedish Environmental Protection Agency. Photo: Christian Fischer / Wikimedia Commons

Raccoon dog. Omnivorous predators that can locally exterminate populations of amphibians and ground-nesting birds. It can also transmit infectious agents such as rabies and the fox's tapeworm to humans. Was deployed in the then Soviet Union. Travel to Sweden via Finland. Extensive hunting efforts have been made to counteract establishment in Swedish nature. Source: Swedish Environmental Protection Agency. Photo: TT

North American ox frog. Come to Europe via aquarium trade. It does not occur wild in Sweden, but in a future warmer climate, the ox frog could possibly become an invasive species in southern Sweden. Eats frogs, spiders and chicks. Spreads fungal diseases to other amphibians. Known for its loud chattering night time. Source: Swedish Environmental Protection Agency. Photo: AP / TT