The false widow spiders make up a considerable part of the Steatoda genus. Over recent years they have attracted growing attention in the UK due to their resemblance to the more dangerous black widow and reports of dangerous bites. Although they’ve been present in the UK for over a century, their numbers and visibility have increased, especially in urban areas. While their presence can be unsettling, understanding these spiders helps separate fact from fear.
Members of the Steatoda genus are sometimes mistaken for black widows because of their round, glossy bodies and dark colouring. However, they are not as dangerous and are only distantly related. False widows share several key features:
- Body shape: Round, shiny abdomen and a smaller cephalothorax (the front body section with the eyes and legs). Males are less rounded with proportionately longer legs.
- Legs: Long, slender legs adapted for web-building rather than hunting.
- Eyes: Eight small eyes arranged in two curved rows.
- Colour: Typically dark brown, purplish, or black, often with pale markings such as cream or reddish patterns on the abdomen.
- Webs: Tangled, irregular webs, usually built in sheltered corners near ground level.
These spiders are nocturnal and often hide during the day. They do not actively seek out humans, and most live quietly without causing any disturbance.
Certain members of the false widows can bite, but confirmed cases are rare. Bites usually happen when the spider feels threatened. E.g. during handling, or if it’s trapped in clothing or bedding. The bite is often compared to a wasp sting: sharp pain, followed by mild swelling or redness. In some cases, people report flu-like symptoms, muscle aches, or nausea, but these effects tend to be short-lived.
These spiders are venomous in the sense that they use venom to subdue prey, but the venom is not designed to be harmful to humans. For most people, a bite causes only mild symptoms. Serious reactions are very rare and usually involve allergic sensitivity. Medical attention is only needed if symptoms worsen or signs of infection appear.
Species of False Widow spider found in the UK
Several species of Steatoda are present in Britain, but only a few are commonly seen:
Steatoda nobilis
This is the most well-known and most commonly reported species in the UK. Originally from Madeira and the Canary Islands, it likely arrived in Britain through shipping in the 19th century and is now well established in southern England, with its range slowly expanding northward.
Appearance: Dark brown or purplish body, with a bulbous abdomen and pale markings often described as a skull, leaf, or horseshoe shape.
Size: Females can reach up to 15 mm in body length (around the size of a 10p coin with legs extended). Males are smaller.
Habitat: Common in sheds, garages, walls, fences, and indoor corners—particularly in warm, sheltered environments.
Steatoda bipunctata
Also known as the “rabbit hutch spider”, this native species is widespread across the UK and typically goes unnoticed.
Appearance: Reddish brown with a faint pale line running across the front of the abdomen and two pale spots toward the rear.
Size: Smaller than S. nobilis, usually around 5–7 mm in body length.
Habitat: Common in outhouses, under window sills, and around garden structures.
Steatoda grossa
Less common in the UK but present, mostly found in coastal areas or heated buildings.
Appearance: Glossy dark brown to black abdomen, sometimes with pale markings but often unmarked.
Size: Similar to S. nobilis, with females up to 10 mm in body length.
Habitat: Indoors, especially in dark, undisturbed places like under furniture or behind cabinets.
False widow spiders are a growing presence in the UK, especially in the south. While they can bite, their venom is mild, and serious effects are rare. Most live quietly out of sight and pose little real risk to humans. Recognising the differences between the species and understanding their behaviour helps reduce fear and encourages a more balanced view of these surprisingly misunderstood spiders.