News Navigator: How dangerous are little fire ants recently found in Japan for 1st time?

The Mainichi Shimbun answers some common questions readers may have about the invasive little fire ant species recently found in Japan.

Question: What are the foreign poisonous ants that were recently found in Japan?

Answer: “Little fire ants,” known as “kokamiari” in Japanese, were discovered in the country. On July 3, about 30 of these ants were found at Mizushima Port in Kurashiki, Okayama Prefecture, marking the first confirmed case of this species in Japan. Their stings can cause severe pain and swelling. Because of their potential negative impact on the ecosystem, including driving away ants that have long inhabited Japan, they are classified as a “designated invasive alien species” subject to import and breeding bans in principle.

Q: They sound scary. What are their characteristics?

A: Little fire ants are a reddish yellow-brown in color, and the length of a worker ant is about 1 to 2 millimeters. They are much smaller than the 2.5 to 6 mm length of regular fire ants, or “hiari” in Japanese, which are also designated as an invasive alien species. This makes them much harder to spot. According to the Ministry of the Environment, although less venomous than fire ants, they may cause allergic reactions.

Q: Where are they from?

A: Although native to Central and South America, the ants found this time were attached to the stands and other parts of containers that arrived from the Philippines via Kobe Port. They have invaded the United States, Africa and New Caledonia, expanding their habitat. They have also settled in Taiwan, and were found in China in 2022.

Q: Is there any possibility these ants are proliferating in Japan?

A: Since they have not been found outside of Mizushima Port and no queen ants have been confirmed, it is believed that they have not settled in the country. In recent years, ants designated as invasive alien species have continued to find their way into Japan, and fire ants had been confirmed in 18 prefectures as of July 21.

Q: What should be done if a person encounters these little fire ants?

A: It is important not to provoke them by suddenly spraying them with insecticides or poking their nests, which could result in them fleeing to the surrounding area in surprise. The Ministry of the Environment urges people to confirm the number of ants and the location where they were found, and to contact the ministry or local authorities.

(Japanese original by Ei Okada, Lifestyle, Science & Environment News Department)