They are large and frequently aggressive. They can decimate farmers' crops and suburban gardens. They are being blamed for damage to infrastructure and the wooden homes that are still common across rural Japan.

Raccoons may look cute and cuddly, but they are rapidly becoming a menace across the country.

And they are just one of 148 species that are on the Environment Ministry's list of invasive alien creatures that are causing similar havoc with local flora and fauna.

"Our research shows that raccoons have expanded their habitats threefold in the last decade," Haruka Yamaguchi of the ministry's Task Force for Countermeasures Against Invasive Species, told DW.

The statistics suggest that raccoons are now found in 44 of the nation's 47 prefectures, and are particularly unwelcome in crop-growing regions.

"We are providing funds to prefectures so they can produce booklets and other literature to educate people about stopping raccoons spreading into more areas, while the farm ministry is providing funds for electric fences and other deterrents," Yamaguchi said.

"It is a constant battle," she added.

Read more: US raccoon scales Minnesota skyscraper, captivates nation

No natural predators

The other problem is that foreign species that lack natural predators in Japan are encroaching on the habitats of local creatures and taking over their ecosystems, in extreme cases putting them at risk of extinction.

One of the most at risk are the insects that are indigenous to Chichijima Island, a tiny speck of land about 1,000 kilometers south of Tokyo, which has become a new home to the green anole lizard, a rapacious, fast-breeding invader.

Some of the insects on Chichijima are not found anywhere else in the world, and there has been a knock-on effect among other inhabitants of the local ecosystem.

Most worryingly, the lizards appear to have found a way to traverse the channels that separate Chichijima from the rest of the Ogasawara archipelago, which was recognized as a UNESCO Natural World Heritage site in 2011. In 2013, the first lizards were found on Anijima Island, which is 500 meters away across a channel.

Experts believe the first lizards were brought to Chichijima by US military personnel when they were stationed on the island in the 1960s, while they may be spreading through the archipelago in tourists' backpacks on the small ferries that crisscross the local waters.

The Celastrina ogasawaraensis, a butterfly designated as a nationally protected species, and the indigenous Ogasawara dragonfly have both been driven to the brink of extinction on Chichijima by the lizards. The plight of local insect life has also been felt by a number of unique species of birds and bats.

Unexpected visitors: wildlife in the city So an elks walks into an office… Not the start of a bad joke, but certainly a silly situation for this moose on the loose. The confused young elk had wandered into an office building in Dresden in eastern Germany on Monday. The 800-kilogram animal broke through a glass door and got stuck between a wall and a window. There, he waited calmly for several hours, just around lunchtime, blocking the way to the building’s canteen.

Unexpected visitors: wildlife in the city Return to the wild After a five-hour standoff, police and local zookeepers sedated the young bull with two arrows shot right into his bottom. The elk was then loaded into a container and taken back into the woods. The incident has inspired puns aplenty about the "deer colleague" who probably came from neighboring Poland. For wildlife experts, it is also sign that the species might re-establish itself in Germany.

Unexpected visitors: wildlife in the city Raccoons on the run While elk are still a rare sight in German cities - or forests, for that matter - many other wild animals have decided to enter the human world for good. The raccoon, a North American native, was released into the wild near Kassel in 1934. Then nature took its course. Today, a few hundred thousand raccoons live in Germany, many roaming through residential neighborhoods like this guy in Berlin.

Unexpected visitors: wildlife in the city Wild boar alarm Not all wild animals are welcome guests. Wild boars regularly cause a stir among home owners in suburbia. The boars can dig up the ground in minutes, causing damage to well-kept gardens. Their numbers have increased substantially over the last 20 years. It is estimated that in Berlin alone, 10,000 wild boars use their sensitive snouts in search of an alternative to acorns and beechnuts.

Unexpected visitors: wildlife in the city Rural exodus The faunal drift to the cities has a number of reasons. First of all, the human habitat tends to be warmer than the wild. Animals will also find food here and be safer from hunters. Secondly, many natural habitats have been turned into agricultural deserts that no longer provide food and shelter. Lastly, urban developments continue to sprawl: often man comes to beast, not vice versa.

Unexpected visitors: wildlife in the city A bear with a problem The encounter of man and beast can, of course, go badly wrong. Bruno the bear became Germany’s most famous fugitive in 2006 when he crossed the Alps and entered Bavaria. After seven weeks of roaming freely, killing sheep, domestic rabbits and one odd guinea pig, Bruno was shot dead. The stuffed animal is now on display at the Museum Mensch und Natur (Man and Nature) in Munich. Author: Peter Hille



Trapping program

The Environment Ministry has placed 36,000 traps in the southern part of Anijima, while a fence is also being erected in an effort to halt the lizards' occupation of the island.

Other foreign creatures have taken up residence in different parts of Japan, with colonies of red back spiders, native to Australia, found in Kawasaki, Okinawa and Osaka, while infestations of venomous fire ants have been discovered in shipping containers imported from China and Southeast Asia. Despite the authorities' best efforts to screen arriving freight and destroy any unwanted arrivals, fire ant queens have been found in areas around Japanese port cities.

Large-mouth bass, which were imported to stock lakes for sport fishermen in the 1920s, have escaped and decimated local populations of freshwater fish, while American bullfrogs and Mississippi crayfish have also escaped captivity to multiply rapidly.

"Right now, the biggest problems seem to be the raccoons and the civet cats, which were brought here in the late 19th century to produce fur," Kevin Short, a professor specializing in environmental education at the Tokyo University of Information Sciences, told DW.

Read more: Want to pet that cute owl? Think again!

Animated TV show

"We get plenty of raccoons here in Chiba Prefecture, where I live, but they only became popular in the 1970s because of an animated television show about a raccoon called Rascal," he said. "People started keeping them as pets, and the pet importers could not get enough of them."

"The problem is that while baby raccoons are cute and friendly, they are big, heavy and aggressive when they become adults. And it becomes impossible to keep them in the average Japanese apartment, which is small and not designed to be a home to that sort of pet," he said.

"So owners had a choice; they could take them to the city to be euthanized – it was not a choice for most people because they had formed an emotional attachment to their pets," he added.

"So they did what they thought was the best thing and they released them into the wild. And now we're seeing the results of that."

And given that many of these imported species are adaptive by nature, Short believes that they will continue to multiply in Japan's countryside and that little can be done to stop that from happening.