Fire ants, a venomous, highly invasive nonnative pest, have been spotted over the past few months in various parts of Japan, prompting the Environment Ministry to both warn the public to seek immediate treatment for stings and take measures to prevent further infestation.

First detected June 9 in Amagasaki, Hyogo Prefecture, fire ants had been identified in 10 locations nationwide as of July 27, from Oita Prefecture to Shinagawa Ward, Tokyo.

The ministry has confirmed one injury caused by a fire ant; a male worker in his 30s developed a rash on his left arm after being stung in a warehouse in Fukuoka on July 27.

Following is a look at why fire ants should be kept out of Japan:

What are the characteristics of fire ants?

They measure about 2.5 to 6 mm long, are reddish brown in color and have a venomous stinger on the tip of their deep-red abdomen.

According to the ministry, fire ants originated in South America but have spread to more than 10 countries and territories worldwide, including the United States, Puerto Rico, Australia, China and Taiwan.

Unlike Japan’s domestic ant species, fire ants build domed hills 25 to 60 cm wide and 15 to 50 cm high.

The invasive species law bans the import, transport or keeping of fire ants in Japan.

How dangerous are they?

The Environment Ministry had in the past said that about 100 people in the United States are killed each year by fire ants, printing this figure in a pamphlet titled “Stop the Fire Ant.” However, the figure was not used in the pamphlet’s current version. A ministry official told The Japan Times last week they couldn’t find any evidence to back the figure up.

Even so, the official stressed the importance of people steering clear of fires ants because it is possible to die from a sting.

According to the Japanese unit of the International Union for the Study of Social Insects, 129 people were hospitalized in Taiwan between 2012 and 2014 after being stung by fire ants, although no cases resulted in death.

Fire ants can also threaten biodiversity and agriculture.

The ministry says the species is “highly aggressive,” killing and consuming insects, reptiles and even small mammals. Officials say fire ants can potentially kill livestock, including cattle or horses.

The International Union for Conservation of Nature considers fire ants one of the world’s 100 worst invasive species that can drive other breeds to extinction, and do harm to human society.

“They breed and spread rapidly and, if disturbed, can relocate quickly so as to ensure survival of the colony. Their stinging ability allows them to subdue prey and repel even larger vertebrate competitors from resources,” says the union’s database. They also proliferate quickly, with queens producing 800 to 2,000 eggs a day.

The economic impact of fire ants on humans, agriculture and wildlife in the United States was estimated at about “half a billion, if not several billion, dollars per year,” according to a 2010 report by the union.

The agricultural impact includes damage to crops and workers, the report says, adding that if inhabited by fire ants, playgrounds may no longer be safe for children.

What happens when a person is stung?

According to the ministry, victims can experience anaphylaxis, a life-threatening allergic reaction with symptoms such as difficulty breathing, decrease of blood pressure and loss of consciousness. Milder symptoms can include breaking out in hives centered around the areas where stung.

Victims may also experience acute pain similar to a burn.

If conditions worsen after a rest of 20 to 30 minutes, it’s best to visit a hospital and report being stung.

If one encounters an army of fire ants, steer clear and contact the Environment Ministry or the prefectural department that handles pest extermination.

What measures are being taken by the government?

The Environment Ministry is urging early detection and extermination.

According to the ministry, all fire ants spotted so far have been exterminated. The sites have been in Hyogo, Aichi, Osaka, Tokyo, Kanagawa, Fukuoka and Oita prefectures.

The ministry has also begun a project to hunt down fire ants at 68 ports nationwide and is taking such measures as setting traps in areas within 2 km from the ports where they have previously been seen. The 68 ports regularly handle cargo from countries and territories where the ministry has confirmed that fire ants exist, including China and Taiwan.

The government has also asked organizations involved in shipping to urge consignors to take active measures, and boards of education to teach students about the dangers posed by fire ants.

Medical institutions and fire departments meanwhile have been informed by their prefectural governments about the appropriate treatment of victims.

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