A poisonous red-back spider was found in the garden of a home in Kawasaki, suggesting the invasive alien arachnid is creeping closer to Tokyo.

The Kawasaki resident found the spider along with an ovisac Monday and used a pesticide on them. The spider was later confirmed to be a red-back, which is listed as an invasive alien species by the government.

The first red-back spider found in Japan turned up in the port of Takaishi, Osaka Prefecture, in 1995, presumably arriving aboard a freighter from Australia.

The National Institute for Environmental Studies has certified that the spider has been located in 18 prefectures since then, but that number is expected to be larger in reality.

“Red-back spiders are pretty harmful,” Masahiro Yoshida, a former Osaka Prefectural Institute of Public Health senior researcher who now heads the Osaka-based Laboratory of Bio Research, told The Japan Times.

He said the spider’s venom can cause a sudden rise in blood pressure and may be lethal to young children or elderly people with heart conditions.

Red-back bites have caused deaths in Australia, Yoshida added, urging municipal authorities, especially in Tokyo, to be on guard.

“Each local government should have an officer in charge of the extermination of poisonous spiders. They should also educate the public on the dangers” of red-backs, he said. Like many other spider species, female red-backs grow much bigger than males and can reach about 1 cm in size.

The spiders, which are black, have a red blotch on their bodies. Only the females are venomous, according to the Environment Ministry. Red-back spiders are usually found in dark, moist and warm places, including inside gutters.

But when an 86-year-old woman suffered a red-back bite in Fukuoka on Sept. 3, the spider was in her shoe. She was taken to a hospital and recovered after taking a shot of serum.

Most municipalities have posted warnings on their websites that red-backs, while not aggressive, will bite if irritated. One should “trample on the spider with their foot or use pesticide for extermination,” warns Joto Ward, Osaka, on its website.

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