All UK spiders are essentially harmless - even the much-feared false widow rarely causes more than local pain. The species that actually warrant action are false widows in colonies and the extremely rare Brazilian Wandering Spider arriving on imported fruit.
- Most common in UK homes: giant house spider, daddy longlegs spider, zebra jumping spider - all harmless
- Worth respecting: false widow (painful bite, not fatal)
- Genuinely dangerous: Brazilian Wandering Spider (banana stowaway - rare but venomous)
Most spiders in UK homes are completely harmless - and even helpful, eating far more flies and other insects than people realise. But a small number can deliver a painful bite, and one or two species are genuinely worth taking seriously. This guide covers the species you are most likely to encounter and what to do about each.
UK Spider Species at a Glance
| Species | Size | Where Found | Risk Level |
|---|---|---|---|
| False Widow | Up to 14mm | Outbuildings, roof voids, sheds | Painful bite, not fatal |
| Giant House Spider | Up to 18mm | Indoors in autumn, runs across floors | Harmless |
| Missing Sector Orb Weaver | ~8mm | Gardens, window frames | Harmless |
| Daddy Longlegs Spider | Body ~8mm, legs to 50mm | Ceilings, room corners | Harmless |
| Zebra Jumping Spider | Up to 9mm | Walls, window frames | Harmless |
| Cupboard Spider | Up to 14mm | Sheds, outbuildings, cupboards | Harmless (mild bite) |
| Brazilian Wandering | 30-50mm | Stowaway on imported fruit | Highly venomous - call a professional |
The Harmless Eight
These are the spiders you will see most often around UK homes. None of them pose a real threat to humans.
Giant House Spider
Large (up to 18mm body), dark brown with hairy legs. Famous for sprinting across living room floors at 1.7 feet per second. Their venom is harmless to humans. The ones you see in autumn are usually males looking for mates.
Missing Sector Orb Weaver
Small, yellowish-brown with a bulbous abdomen bearing a distinctive leaf-shaped marking. Most often found sitting in its web outdoors or in window frames. Easy to remove.
Daddy Longlegs Spider (Pholcus phalangioides)
Tiny body, very long thin legs (up to 50mm). Hangs from ceilings in fine cobwebs. Non-aggressive and harmless. Note: this is a true spider - confusingly different from “daddy longlegs” the harvestman (not actually a spider) and crane flies (insects, not arachnids).
Zebra Jumping Spider
Tiny (up to 9mm) with black and white stripes. Found on walls and window frames. Famous for being able to jump distances three times their body length. Harmless and oddly charming.
Cupboard Spider
Closely related to false widows but smaller and rounder. Dark, almost black. Lives in sheds, outbuildings and cupboards. Harmless, though a bite may cause mild local discomfort.
The Ones to Watch
False Widow Spider (Steatoda nobilis)
The most-cited “concerning” UK spider. Up to 14mm long, dark brown with cream markings on the abdomen that resemble those of black widows (hence the name). Their bite can cause significant local pain and swelling. Not fatal and rarely requires medical attention, but worth respecting.
Sightings have risen steadily over the past two decades. False widows can establish colonies in roof voids, outbuildings and garden sheds - if you find one, look for more.
Brazilian Wandering Spider (Phoneutria)
Not a UK native. Occasionally arrives as a stowaway on imported fruit (especially bananas) from South America. One of the most venomous spiders in the world. Encounters are extremely rare - you are far more likely to see a tarantula at a pet shop - but if you suspect you have found one, do not handle it. Call a professional immediately.
What Counts as an Infestation?
Seeing one or two spiders in autumn is not an infestation - it is normal seasonal behaviour. Spiders move indoors in autumn for warmth and to find mates.
Consider professional removal if you see:
- Multiple webs appearing repeatedly in the same area despite cleaning
- Egg sacs (pale silk pouches) in webs - each holds hundreds of spiderlings
- Confirmed false widows in or near the home, especially with young
- Recurring sightings of large spiders in normally well-kept indoor spaces
Daddy Longlegs Confusion
The term “daddy longlegs” causes endless mix-ups. In the UK it refers to three different creatures:
- Crane flies - insects with two wings and very long legs. Appear in late summer. Harmless.
- Harvestmen (Opiliones) - arachnids but not spiders. Eight legs, fused body, two visible eyes.
- Daddy longlegs spider (Pholcus phalangioides) - a true spider with eight legs and an obvious abdomen, hangs from ceilings.
All three are harmless.
What to Do Next
For most UK spiders, removal by hand (using a glass and card) is enough. For false widow colonies or recurring problems, see our spider control service or the detailed spider species guide for further identification help.
If you suspect a Brazilian Wandering Spider - particularly after unpacking imported fruit - do not attempt to deal with it. Call our RSPH (BPCA) Level 2 certified and trainee techs immediately.
Frequently Asked Questions
Are any UK spider bites fatal?
No native UK spider has caused a confirmed death. Even false widow bites, the most cited concerning UK spider, produce significant local pain and swelling but are not fatal. The only genuinely dangerous spider that could appear in the UK is the Brazilian Wandering Spider - arriving as a fruit-shipment stowaway, not as a resident species.
Why do I see more spiders in autumn?
Autumn is mating season for many UK species. Males roam looking for females, falling temperatures push spiders indoors for warmth, and the giant house spiders you see racing across the floor are almost always males searching for mates.
How do I tell a false widow from a black widow?
UK doesn’t have true black widows. False widows have cream-coloured markings on the abdomen rather than the bright red hourglass of the American black widow. False widows are also smaller (max 14mm body vs ~38mm for a black widow).
Do I need to clear cobwebs to deter spiders?
Yes. Clearing webs removes the food traps spiders depend on, and removes the visual cue that the space is suitable for new spiders. Regular dusting and clearing of ceiling corners is the single most effective DIY deterrent.
What about the spider in my bath?
The spider didn’t climb up - it fell in and can’t climb out (smooth porcelain plus oily residues defeat the leg hairs). It came up through the overflow or down from a higher fixture. Place a small piece of tissue or a plastic ramp and it can escape, or scoop it out with a glass.