Steatoda grossa

Length 7 to 10.5 mm (larger than the similar Steatoda bipunctata 4.5 to 7 mm). The abdomen of this false widow is a red-brown colour with a crescent shaped stripe at the front and three pale triangular spots along the top. These markings vary from spider to spider, sometimes cream coloured and sometimes purple or very dark brown. Markings are variable and this species can only be separated from Steatoda bipunctata by close examination of the genitals. Typical specimens can be determined from good photos but some need checking. This spider is found most often in and around buildings but has also been taken in sheltered locations outdoors, e.g. in cracks in walls and on under-cliffs. The spider has been found in the sewer system in Leicester. Adults have been found at most times of the year. It constructs the scaffold webs typical of the genus and has been observed feeding on pill-woodlice. S. grossa is a cosmopolitan species found in many parts of the world, including North America, Australia and New Zealand, and Europe. The spider is known from scattered locations across southern Britain becoming scarcer further north. The species was commonest in coastal areas of south-west England but has increased in frequency in more recent years in the east and northwards. 368 British records for this species to early 2015.