More than 2,000 fire ants were exterminated in Osaka port on Friday after turning up in a shipping container from China, government officials said.

The discovery of the invasive species native to South America is one of the largest since an estimated 2,000 were discovered in Muko, Kyoto Prefecture, in October last year, the Environment Ministry said Saturday. No queen ant was found.

The stinging ants have turned up in Tokyo and 11 prefectures since they were first detected in May 2017 in a container from Guangzhou, China, that was unloaded in Amagasaki, Hyogo Prefecture, according to the ministry.

According to the ministry and the Osaka Municipal Government, the container left Shenzhen, China, on June 5 and arrived at the Osaka port on June 12 via Hong Kong. It was transferred two days later to Kishiwada, Osaka Prefecture by land.

On Friday, about 100 of the ants were found while the cargo was being unloaded. A worker got stung on his back and left hand. This led to the discovery of the rest of the ants, which were promptly exterminated. Although insecticide was sprayed around as a precaution, a ministry employee managed to get stung on the left hand.