Why big spiders appear in autumn
The large spiders that run across the floor in autumn are mostly adult males, wandering in search of a mate. House spiders of the groups Tegenaria and Eratigena are big, long legged and hairy, and a male can span 10 to 12 cm from leg tip to leg tip.
Are house spiders dangerous?
A giant house spider can bite if you pick it up, but its bite is not considered dangerous to people. The kindest thing to do with a wandering one is to let it outside. While they are indoors, spiders also eat flies and other small pests.
The long-bodied cellar spider even hunts other spiders. It wraps its prey in silk while keeping a safe distance on its long legs.
False widows
False widows are spiders of the genus Steatoda, with dark, rounded bodies and untidy tangled webs. The three met most often in homes are the rabbit hutch spider, the false black widow, also called the cupboard spider, and the noble false widow. The noble false widow has a body about 7 to 14 mm long, females being larger than males, and the false black widow reaches about 10 mm.
The noble false widow comes from Madeira and the Canary Islands and has spread a long way from there, probably as a stowaway in ship cargo.
It bites only when it is trapped or pressed against the skin, often inside clothing. Males bite more often than females because they are the ones that wander indoors looking for a mate. Most bites hurt about as much as a wasp sting, but a small number of cases have led to stronger symptoms or an infected wound. Seek medical help if a bite gets worse or you feel unwell.
Black widows and the brown recluse
These spiders do not live everywhere, and what follows applies only where they occur. Each has its own page in the guide, which shows the volume it belongs to.
Black widows, genus Latrodectus, are shiny black with a red hourglass mark on the abdomen. They live mainly outdoors, in firewood piles, garages, sheds and outhouses. Only the female is a danger to people. She is about 5 to 15 mm long, and the male is much smaller.
Black widows are not aggressive. They bite when they feel threatened, which usually means someone has reached into the place where one is hiding, such as a wood pile, a garage shelf or gardening gear. The bite is usually painful, and severe pain and muscle cramps can begin within an hour. Contact a poison centre or a doctor after a bite.
The brown recluse carries a violin shaped mark on its back and has only six eyes, set in three pairs. Its venom can damage the tissue around a bite, and some bites need medical attention.
