Redback spiders enjoy Tokyo enough to start a family

Venomous redback spiders, once an occasional concern when found in shipping containers, have started to breed in Japan.

The Tokyo Metropolitan Government this week warned residents to be on the lookout for the spider, indigenous to Australia, after 10 redbacks and dozens of eggs were found in parks in the Mitaka district of western Tokyo.

More of the creatures have been found in Koto ward, prompting the authorities to caution people to wear gloves when they are gardening and to be careful in parks. The spiders are relatively small - the body of the larger female of the species is usually only 1cm in length.

Anyone bitten by a redback - which gets its name from the distinctive markings on its back - is likely to experience headaches and nausea. In more serious cases, a bite can cause muscle paralysis and even death, although deaths among humans are rare.

The first redbacks were found close to Osaka port in 1995. It is assumed that they arrived aboard a freight ship.

There have since been sightings in many parts of the nation.