Deadly red-back spider spreads across Japan

October 18, 2012


FUKUOKA--A venomous spider endemic to Australia has established colonies across Japan after apparently being brought in on cargo containers.

The red-back spider was first identified in 1995 in Takaishi, Osaka Prefecture, experts say, and by Oct. 1 the spider had reached 22 prefectures, the majority of them in western Japan.

In September, a spider bit a woman in her 80s from the Higashi Ward of Fukuoka city. She suffered breathing difficulties.

While the spiders are not aggressive, the female spider has a virulent poison that can cause spasms and fever. Deaths have been recorded in Australia.

"I have become more aware of whether there are spiders in areas where children play," said Mikiyasu Koga, 44, who was recently taking his 4-year-old daughter to a park on Higashi Ward's Island City.

Japan's Environment Ministry has said the red-back spider is often found near Japanese ports. Officials believe it originally arrived aboard cargo.

The red-back spider was first identified in Fukuoka's Higashi Ward in 2007 and since then specimens have turned up there every year. But this year saw an increased number of sightings. Last month alone there were 63 recorded sightings, as of Sept. 28.

City officials plan to erect warning signs close to harbor facilities in the neighborhood urging vigilance.

However, city officials say there is no need to panic because the spiders are not aggressive.

"People do not have to become excessively fearful," said one official.

In June, the red-back was identified for the first time in Shingu, which borders Fukuoka city. In September, one was found near a resident's front door. That same month, the spiders turned up, too, in Koga, Fukuoka Prefecture, and at the Ground Self-Defense Force Camp Metabaru in Yoshinogari, Saga Prefecture.

Masahiro Yoshida, who heads Osaka-based Ikimono Kenkyusha ("Living Things Research Company"), is a former senior researcher with the Osaka Prefectural Institute of Public Health.

He said red-back spiders prefer temperatures around 25 degrees and often live in ditches or within fence posts. The peak breeding period is summer.

There have been sightings of large numbers at a time. In Amagasaki, Hyogo Prefecture, and Kyoto city more than 100 spiders turned up in city parks in September alone, officials said.

"The spiders' distribution has spread because of Japan's warm climate and the relatively few natural predators," said a Fukuoka city government official.

Many local governments seem unprepared to deal with the problem.

After the woman's bite in Fukuoka, the city's stores of antitoxin were all found to have had an expired shelf life.

Under the Invasive Alien Species Law, it is Japan's central government that should take the lead in extermination efforts.

However, an official with the Environment Ministry's Office of Alien Species Management said, "Our priority is to exterminate those species that damage biodiversity conservation areas, such as national parks."

For that reason, extermination of the red-back spiders is being left up to local governments.

"One reason for the spread in the spider's distribution is the haphazard pattern of extermination efforts so far. The spider's spread could be stopped through a more carefully planned extermination," said Osaka's Yoshida.

(This article was written by Taro Ono and Tomoko Yamashita.)

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The red-back spider found in Fukuoka city in September (The Asahi Shimbun)

The red-back spider found in Fukuoka city in September (The Asahi Shimbun)

  • The red-back spider found in Fukuoka city in September (The Asahi Shimbun)

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