Which spider is in my house?

How to identify the common house spiders

Giant house spiders (*Eratigena* and *Tegenaria* species) are brown, hairy and long-legged, with bodies around 12 to 15 mm. Males have the biggest leg spans. The Natural History Museum says the largest British house spider, the cardinal spider, can reach a leg span of 12 cm in adult males.

False widows (*Steatoda*) are different: shiny, round-bodied and dark brown to black, often with a pale crescent or skull-like pattern on the abdomen, though the pattern can fade. The noble false widow is 8.5 to 14 mm in females; the cupboard spider is 6.5 to 10 mm; the rabbit hutch spider is 4.5 to 7 mm.

Lookalikes

• Daddy-long-legs spiders have tiny bodies and very thin legs and hang in loose webs in corners.
• Money spiders are tiny.
• House centipedes have far more legs. See centipedes.
• Black widows are not found wild in Britain; a round dark spider here is nearly always a false widow.

Why they are indoors, and are they harmful?

The Natural History Museum says male house spiders leave their webs in autumn, from about August to October, to look for females, and often come in through open windows, chimneys or gaps under doors. Few spiders can live comfortably in a modern centrally heated home.

Of about 650 UK spider species, the Natural History Museum says only around 12 have been recorded biting people, and just two or three have caused significant symptoms, typically localised pain and swelling. The noble false widow is the one most reported. Its bite is usually compared to a wasp sting and mostly happens when the spider is squashed against skin, for example in bedding or shoes. Confirmed bites are rare. If the bite swells, spreads or you feel unwell, see a doctor or call NHS 111.

How to get rid of them

The Natural History Museum notes that nobody has invented an effective spider deterrent, and its advice is to stop them entering: close windows, plug gaps with filler, fit draught excluders and insect screens.

• Vacuum webs and egg sacs.
• Reduce clutter in corners, sheds and garages.
• Shake out shoes and clothes left on the floor.
• Remove the spider with a glass and card.

Spiders also eat flies, silverfish and woodlice, so tolerating one helps with other pests.

When a professional is worth it

Hardly ever. Spiders do not infest homes in the way beetles or rodents do, and spraying does not stop new ones arriving. If you are worried about false widows in a particular spot, ask for advice on sealing and clearing it, but for a normal home, seal gaps and clear webs yourself.