Noble False Widow

Steatoda nobilis has a brown bulbous abdomen with cream coloured markings that are often likened to the shape of a skull. Their legs are reddish-orange. Both female and male S. nobilis can be distinguished from other spiders of the same genus by their large size and typical colouration. Females range in size from about 9.5 to 14 mm in size, while males are 7 to 11 mm. The largest females are 13.7 mm in size, while the largest males can be 11.66 mm in size. The males can be distinguished by their conformation of the palp and by their ventral abdominal markings. The females can be distinguished by their epigyne. The variation in size, shape and markings that have been observed is not thought to be due to location. Spiders found centimetres apart and siblings born from the same egg sac can look very different.

Male and female juvenile spiders are indistinguishable from each other.

The spider is originally from the Canary Islands and Madeira. It is an introduced species across Europe, parts of the United States and North Africa, and likely spreading. It was found for the first time in 2011 in Cologne, Germany. In England it has been reported mostly in southern counties, but its range was reported to be expanding northwards in the 21st century. In 2011, the spider was reported as an established invasive species in the USA, in Ventura County, California. In January 2016, it was reported that Steatoda nobilis had been found in Chile, the first time that the species had been recorded in the southern hemisphere. Research published in December 2018 showed that it was also established in Colombia and Ecuador. The spider has been in New Zealand since at least 2023. It is considered to be one of the world's most invasive species of spider. Seaside cities and villages with a temperate climate are especially favourable habitats for S. nobilis. The first recorded observation of S. nobilis in England dates back to 1879. The first recorded observation of S. nobilis in Ecuador was in 2014 at several locations as high as 2800 meters. Between 1985 and 2010 there was no reporting of large numbers of S. nobilis anywhere, and scientists consider this to be a typical lag phase that is a phenomenon observed in many invasive species. …

S. nobilis can eat both vertebrates and invertebrates. In Ireland, they were observed to eat woodlice. All of S. nobilis’s liquid requirements are observed to come from its prey. In laboratories they seem to thrive without water and in extremely dry conditions. In Ireland they have been observed to prey on protected reptile species. In southern England, an adult female was observed to haul up and digest a pygmy shrew ten times the spider's size.