Spring has come — the season when cherry blossoms bloom nationwide.

But ecologists warn that Japan’s most popular sites for hanami (cherry blossom-viewing) might disappear in the next couple of decades.

This is because red-necked longhorn beetles, a species foreign to the country, are eating the blossoms and damaging the trees.

Red-necked longhorn beetles are one of many alien species disrupting the environment, prompting the government to take action.

Below are questions and answers on what kinds of species are posing a threat, how they came to Japan and what measures the government is taking:

How many alien species are there in Japan and what can be done to control them?

Of all animals, insects and plants in Japan, about 2,000 are estimated to be alien species — in most cases introduced as pets.

The Invasive Alien Species Law, which took effect in 2005, bans 132 “specific alien species” deemed harmful to people, the environment and other domestic species.

Listed under three categories, the first includes species that disrupt biodiversity by eating and depopulating other species. Red swamp crayfish are among them.

The second category includes poisonous species that are life-threatening to people, such as the redback spider.

The third covers alien species that harm agriculture, forestry and fisheries, including raccoons that eat crops.

The law bans the rearing, keeping, transporting or importing of such species, except in special cases such as for research. Releasing banned alien species into the wild is also prohibited.

Those who violate the law face three years in prison or a fine of up to ¥3 million. Corporate entities face a fine of up to ¥100 million.

The Environment Ministry has three basic principles regarding banned species: Don’t let them into the country, don’t release them into the wild, and don’t let them spread.

Are red-necked longhorn beetles designated as a banned alien species?

Not yet, but the government is moving to give them this status.

First spotted in Aichi Prefecture in 2012, the insect rapidly spread nationwide.

As of March, it was reported as inhabiting seven prefectures, including Tokyo, Osaka and Gunma.

In Gunma, cherry blossom trees at Akagi Nanmen Senbonzakura, a well-known area in Maebashi for cherry blossom-viewing, were damaged by the insect.

To combat the situation, the Environment Ministry announced this month that it is considering introducing 14 organisms, including the red-necked longhorn beetle, to its list of specific banned alien species.

Other species under consideration include 10 types of stag beetles from the Neolucanus family, which are originally from Taiwan and India and now seen in Kagoshima and Okinawa prefectures. And a butterfly species called the red ring skirt that is reportedly inhabiting the Kanto region.

The ministry plans to add the 14 species to the list as early as this summer.

What are some of the most well-known alien species?

The most notable would be the giant snapping turtle, which can bite off a man’s finger.

Typically found in North America, they were brought to Japan as pets in the 1960s.

After irresponsible owners released them into the wild, they are now found nationwide, including in Tokyo, with some even living in Ueno Park’s Shinobazu Pond and Hikarigaoka Park in Nerima Ward.

The turtle overpopulated the Inba Swamp in Chiba Prefecture, forcing the prefecture to hire — for the first time ever — a hunter to clear them.

It is believed some 16,000 giant snapping turtles live in the swamp, and Chiba Prefecture says it will have to exterminate at least 1,200 by the end of the year.

What extermination programs are conducted by the central government?

One long-term extermination program conducted since 2006 by the Environment Ministry is on mongoose, which are widespread throughout Okinawa and Kagoshima prefectures.

Mongoose were first brought to Japan in 1910 from India, ironically to exterminate the deadly habu snake that was threatening people’s lives in Okinawa.

However, rather than eating snakes, mongoose went after other rare animals, including the Amami rabbit and Amami tip-nosed frog, threatening them with extinction.

The damage from mongoose was especially serious on the island of Amami in Kagoshima. After about 100 mongoose were initially released into the wild on the island in 1979 to eradicate habu, the number grew to over 10,000 at its peak in 2000.

To combat the situation, prefecture officials, dubbed “Amami Mongoose Busters,” placed over 30,000 traps throughout the island, while using monitoring tools such as cameras and handling dogs trained to detect the mongoose scent.

The Environment Ministry program ended in 2015, but the prefecture said it will continue to hunt mongoose. Over 32,000 mongoose have been eradicated so far, but the goal is to wipe out the entire population by 2022.

Are there harmful species not yet designated under the law?

Yes. Among them are the red-eared slider turtle, which has become overpopulated, causing significant stress on the environment.

A study has shown there are about 8 million red-eared sliders, eight times the total number of domestic turtle species. It is believed that about 90 percent of all turtles in Japan are red-eared sliders.

But the Environment Ministry has been hesitant to put them on the list of specific alien species, fearing many people who keep them as pets may release them into the wild to avoid being fined or imprisoned.

Originally from the United States, red-eared sliders, known as midorigame in Japan, are believed to have been brought to the country in the 1970s and popularly sold at festivals and pet shops.

Koichi Goka of the National Institute for Environmental Studies previously told The Japan Times that the turtles live about 60 years, and are often dumped in ponds and rivers when they grow too big.

The ministry said red-eared slider turtles have mainly colonized waterways in the Kanto, Chubu and Inland Sea regions, harming the ecosystems there. They are estimated to consume up to 320 tons of water weeds a week.

The ministry plans to restrict imports, increase culls and crack down on people who abandon them as pets.