You probably have them in your bedroom. But they're not the flesh-eating monsters you think they are
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You probably have them in your bedroom. But they're not the flesh-eating monsters you think they are

White-tailed spiders may be Australia's most misunderstood animals, caught in a tangled web of myth and hysteria. We take a closer look.

By Chloe Booker

You'd be forgiven for believing Australia's white-tailed spider is a flesh-eating monster, such is the (rotting) tissue of lies it's been caught in.

Its bad reputation was amplified last year when a western Victorian man, who had his legs amputated after developing a supurating wound, blamed the spider. Months later, doctors pointed to the arachnid when a Melbourne woman almost lost her toe.

For decades, similar news articles have taught us that one quick bite from the spider, commonly found hidden in the nooks and crannies of our homes, can lead to the victim losing a limb.

The truth is that's nothing more than tall tales, with experts proving long ago that white-tailed spiders are about as harmful as bees (for those not allergic to bees) and recent studies indicating that something else is to blame for the flesh-eating wounds.

But this doesn’t make white-tailed spiders any less interesting. They are complex creatures, from the tops of their hairy pincers to the dab of camouflage white on their "tails".

Let's take a look under the microscope.

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So where do you find these spiders?

This won't come as good news to arachnophobes: white tails love to lurk in our homes as we sleep.

Largely nocturnal, they prefer warm and dry climates, making our houses their perfect residences. They enjoy being outdoors too, under tree bark, mulch, leaves, rocks or logs – but one of their favourite spots is our bedrooms. They are more likely than other spiders to be found where we sleep, with experts believing this could be due to the increased heat from our bodies.

Mating can be a dangerous game for male white-tailed spiders. If they approach it the wrong way, they could end up as their interest's dinner.

Males approach females from the front and wait until they get a signal that she accepts. If they don't wait, the female can pounce.

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If mating is successful, eggs begin to hatch in spring and peak in summer. You're more likely to see white tails in the warmer months as cold air immobilises them, with many dying in winter – most don't make it through a year.

And while white tails might not be deadly to humans, they certainly use a clever trick to lure black house spiders to their deaths. As web spinners, black house spiders can’t see very well, with their sight undeveloped beyond sensing night and day.

White tails play this to their advantage, using their legs to “strum” black house spiders' webs, mimicking the movements of their prey. When the house spider runs blindly towards what it thinks is its dinner, the white tail pounces.

Another myth about white tails is that they eat daddy long legs spiders and co-opt their venom. You might have been told daddy long legs venom is toxic to humans – only they can’t bite people, due to their long legs and feeble fangs.

Also, daddy-long-legs are more likely to eat white tails.

But white tails also enjoy eating their own species. This is simply because they can't tell they belong to the same spider family. To them, another spider is just another food source.

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So why are white tails blamed for flesh-eating diseases?

The first lies spun about the white-tailed spider were in the early 1980s when they were named as the so-called mystery spider responsible for a spate of necrotic lesions, or flesh-eating ulcers, in southern Australia.

It seems our collective fear of spiders has led to mistaken identity – victims and sections of the medical community still assume that white tails are to blame for these conditions.

The myth was first busted in a 2003 landmark study of 130 white-tailed spider bites, where an expert had caught and identified the spider afterwards. The study found that not one white tail had caused an ulcer or infection.

Experts Geoffrey Isbister and Michael Gray concluded that white tail bites caused only mild pain in most cases or a painful, itchy red lesion in almost half.

Fewer than one-third of cases involved severe pain (which is classified as greater than or the equivalent to a bee sting).

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Another study a year later investigated nine patients whose ulcers had been blamed on white tails or other spiders, with all found to have been misdiagnosed.

What do you do if you're bitten?

We spoke with one person who believed she was bitten by a white tail in bed – three times across her back – in February. Her daughter, who was sleeping beside her, was bitten under the arm. She says at first it felt like a mosquito bite, but "it's itchy and then if you scratch it, it feels a bit like a nettle sting".

Most bites require no treatment, but victims can clean the area and apply an ice-pack to reduce swelling if needed.

Panadol can be taken to reduce pain if necessary and tetanus shots should be up to date, as with any bite or wound.

What does cause flesh-eating ulcers?

It is believed many of the cases attributed to white tails are in fact Buruli ulcers.

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The gruesome open sores are caused by a bacterium called Mycobacterium ulcerans. Scientists are now investigating whether it is spread by mosquitoes and possums.

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If left untreated, these ulcers can cause extreme pain as the bacteria corrodes skin and capillaries, all the while releasing a toxin that suppresses the immune system and leads to gangrene. Some extreme cases have led to limb amputation.

Health experts have sounded the alarm as the number of cases continues to grow without evidence of how it's being spread.

Data from Victoria’s Department of Health and Human Services shows there were 339 cases of the ulcer in the state in 2018, up from 65 in 2013. Incidences are also spreading geographically from the Mornington and Bellarine peninsulas.

A $3 million state- and federal-funded research project is looking for answers.

So, Australia, it's time to stop blaming our white-tailed little friends.

Thanks to Ken Walker, senior curator of entomology at Museums Victoria; Dr Robert Raven at Queensland Museum; and Associate Professor Bill Nimorakiotakis at Epworth Hospital.

Chloe Booker is a reporter at The Age.

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