False widow spider
The false widow spider is one of a group of spiders (Steatoda species) that resemble the notorious black widow spiders (Latrodectus species) and often arouse concern when found in Britain. In fact both groups belong to the same family, Theridiidae, or comb-footed spiders, and live in a similarly constructed tangle-web.
False widow spider
Steatoda grossa
Identification
This species can appear very black but on closer examination the specimens are characteristically plum coloured.
Distribution
The false widow spider is a native species that is usually found in or near man-made structures such as buildings, sheds and fences.
Traditionally it has been most commonly found along the south coast of England, particularly in the south west. However, since the mid 1980s it has steadily increased its range northwards, largely due to a succession of mild winters, and is now more commonly found throughout the south, midlands and Wales. Worldwide it has a cosmopolitan distribution including Europe, Asia and North America, however, it is not usually found in tropical regions.
Behaviour
Species of Steatoda hang upside down in small webs known as tangle webs which are typically built in dark corners.
Life cycle
The life cycle lasts about one to two years and the females live longer than the smaller males, producing white, spherical egg-sacs at intervals. Eggs may take some months to hatch.
Living with humans
If handled unwisely or accidentally, an adult female Steatoda grossa is capable of biting humans but the smaller males are not really able to. A bite may cause a certain amount of pain and often a degree of swelling in the affected area. These symptoms may last for a couple of days but are unlikely to be more serious than that. However, if symptoms persist it would be advisable to consult a doctor.
Toolbox
Last year nearly 100,000 specimens were loaned to scientific institutions and researchers worldwide.
