Study conducted in Mayo makes new discovery about venomous spiders

Scientists have found that noble false widow spiders, capable of delivering venomous bites that are dangerous to humans, make up more than a third of spiders found in urban habitats across Ireland.

The study was carried out by scientists at the Dugon Venom Systems Lab at the University of Galway.

It recorded the species in Mayo and Sligo for the first time, adding to its previously documented presence in 16 other counties.

The authors said the spider has “rapidly expanded its distribution and the density of its populations throughout Ireland since its establishment around the late 1990s."

To examine its spread, researchers surveyed spider populations in six urban areas — Dublin, Cork, Waterford, Galway, Sligo and Castlebar — over an 11-month period.

The noble false widow, or Steatoda nobilis, is a shiny brown spider with a rounded abdomen marked with pale, skull-like patterns. It is typically found around buildings and garden structures.

Females grow to about 1.4cm in body length, while males are slightly smaller.

The team studied spiders living on 10-metre sections of fences around buildings and public spaces and carried out surveys at night, when spiders are most active.