Government scientists are warning the public to beware after what's believed to the be first siting of a deadly black widow spider outdoors in Bermuda.

Venom from the insect is 15 times as toxic as the venom of the prairie rattlesnake and can kill, although the spider is only likely to attack if under threat or to defend its eggs.

The insect was found by Steven Grier at his work at Bay Imports and Marine Services at the Heron Bay Marina in Southampton two weeks ago.

Mr. Grier, 25, said: "I saw the tell-tale hour-glass red markings under its body and was suspicious but I had never seen one before. It was in a concrete block."

Government insect expert Claire Jessey said normally black widow spiders were found in crates of fruit and vegetables shipped from abroad.

She said: "I think people need to know there is a risk there may be more out there."

She said the spider might have escaped from the nearby Heron Bay marketplace. Although a search of the site did not reveal any more she added: "I am worried about how long this has been outside, it may have had a second generation."

The black widow, which is about half an inch long, usually stays hidden in its messy webs found in out of the way places.

But if they do bite, sometimes leaving tiny red marks like pinpricks, it can lead to paralysis of the diaphragm, profuse sweating, swollen eyelids.

More severe cases can cause stomach pain similar to appendicitis and pain in the soles of the feet and back. Other symptoms include nausea, tremors, laboured breathing and speech and vomiting.

During this time a feeble pulse, cold clammy skin, unconsciousness, convulsions and even death can occur if the victim does not get immediate treatment.