Are white-tailed spiders dangerous?

The reputation is worse than the spider

White-tailed spiders have a fearsome reputation in New Zealand and Australia, largely built on reports linking them to necrotic ulcers - wounds where the flesh appears to break down.

That link has been investigated properly. A study following confirmed white-tailed spider bites, where the spider was actually caught and identified, found no cases of necrotic ulceration. The ulcers attributed to white-tails turned out to have other causes, often bacterial infection.

What a bite actually does

• Local pain, often described as a burning sting
• Redness and swelling around the bite
• Itching, sometimes lasting a few days
• Occasionally nausea or headache, though that's less common

When to see a doctor

If the site becomes increasingly painful, hot, or starts spreading, see a doctor - that suggests infection, which is treatable and is the thing actually worth watching for. Any bite causing breathing difficulty or a widespread reaction is an emergency, as with any bite or sting.

How to identify one

Dark grey to black, 12-18mm long, with a distinctive white or cream spot at the tip of the abdomen. They don't build webs to catch prey - they hunt at night, which is why they turn up in bedding and clothing left on the floor.

Keeping them down

White-tails hunt other spiders, so reducing general spider numbers around the outside of the house reduces their food supply. Shake out clothing left on the floor and check bedding if you're worried - that's where most bites happen.