The biting truth about white-tailed spiders

The biting truth about white-tailed spiders

White-tails are blamed for lots of nasty symptoms, and have developed something of a bad reputation, but is it deserved? Bug expert Phil Sirvid sorts fact from fiction.

White-tailed spider. Te Papa
White-tailed spider. Te Papa

How painful is a white-tail bite?

A study of 130 verified white-tail bites from Australia found they were always very painful, although the authors did not find much in the way of other effects beyond local redness and swelling. So, treat white-tails with caution because the bite will hurt, but you shouldn’t expect much in the way of other consequences beyond minor local symptoms if you look after the bite wound.

None of this stops the white-tail being blamed for a variety of conditions even when there is no proof of a spider bite at all. Examples of such misdiagnoses have been reported in the medical literature. This is not to trivialise the very real symptoms people may be suffering, but nobody is helped by blaming the wrong culprit.

How venomous are white-tails?

White-tails are blamed for a lot of nasty symptoms, particularly in relation to the skin. However, studies have shown that there is nothing in white-tail venom that’s of particular concern for humans.

It’s theoretically possible that some people might be especially sensitive to white-tail venom, but there’s no evidence that this is true for the majority of the population at large.

Secondary infections (i.e. infection present in the environment entering a wound at a later time) are sometimes blamed on white-tails, even if no spider is seen. These can happen with any skin breakage, be it a bite, graze, or sting. In some cases this may be serious, but the risk of infection can be greatly reduced by keeping skin breakages clean.

White-tails may have a potential role here in that they are capable of breaking human skin with a bite, thus creating a potential entry point for infection to enter the body. However, there is no evidence to suggest these spiders directly transmit bacteria or other pathogens in the act of biting.

But even if their venom is not dangerous, white-tails deserve respect because of how mechanically strong their bite is.

Where do white-tails come from?

Some people think white-tails are a relatively recent arrival in New Zealand, but they’ve been recorded here since the 1870s.

They come from Australia and almost certainly arrived via the trans-Tasman transport of goods and people. They can go several months without feeding so a short sea voyage to New Zealand wouldn’t be difficult.

How many species of white-tail are in New Zealand?

We have two species currently recorded here. In the North Island we have Lampona murina while in the South Island we have L. cylindrata.

While it’s entirely possible that both species have been transported over Cook Strait, I’ve yet to actually see these spiders in the ‘wrong’ island. They’ve also reached more far-flung parts of New Zealand such as the Kermadecs and I’ve seen them in the Chathams.

Both species are very similar in appearance and you’d need a good microscope to separate them. They also have quite similar habits as specialist hunters of other spiders.

Where do they live?

By day they like living in cracks and crevices, something we humans provide in abundance with our homes.

They also like living under loose bark in tree species we’ve imported from Australia.

What do white-tails eat?

White-tails are helped to prosper by the presence of two other Australian species long-established in New Zealand, the black house spider, and the grey house spider (respectively Badumna insignis and B. longinqua). As their common names suggest, these like to live around homes and white-tails are quite happy to feed on them.

These are not the only spiders they prey on, but their abundance means these two species are a frequent food source.

When and how do they hunt?

The best time to see white-tails at work is after dark. The white-tail will very slowly and carefully enter a web. It starts plucking threads, trying to entice the web’s owner to come within attack range. Once it does, the white-tail strikes hard and fast. It needs to kill such dangerous prey as quickly as it can. Forcefully deployed fangs delivering venom ensure this happens. However, if the other spider attacks first, the white-tail will end up as prey rather than predator.

The myth about white-tails and daddy long-legs

One of the enduring myths about white-tails is that they are not especially dangerous to people unless they eat daddy long-legs spiders and co-opt their venom.

Daddy long-legs spider. Te Papa
Daddy long-legs spider. Te Papa

The story goes that the daddy long-legs is particularly toxic to humans, but its feeble fangs means it can’t bite people. This is all – to put it mildly – complete rubbish.

We know the daddy long-legs can bite and the venom is not dangerous. Even if it was, white-tails have no ability to transform their own venom by taking on the venom of another species. It would be a neat trick if they could.

It’s also worth noting the daddy long-legs is one of the white-tail’s more formidable opponents. That’s because the daddy long-legs is incredibly attuned to what’s happening in its web. No matter how careful it is, it’s virtually impossible for the white-tail to avoid being noticed. Once detected, the daddy long-legs will rain sticky silk down on it. In no time at all, the white-tail is wrapped in silk and is being hauled up by the daddy long-legs for lunch.

More information about white-tailed spiders on Collections Online

21 Comments

  1. Would the author of this article be interested in submitting themselves to a scientific experiment? To be bitten by a whitetail and treat it as if it was just a general abrasion, no antihistamines, no antiseptics. I’d love to see the results

    1. Author

      Hi Jason, I’m not sure what your point is. We have a good study of 130 genuine bite cases. From that we know the bite hurts (which is why I’m not volunteering!) and other symptoms are minor. A single new data point is unlikely to tell us much.

      I’m not sure why you would advise not looking after the wound if I was bitten for the sake of experimentation. As with any skin breakage, the potential for infection to enter the wound later is there. I suggest good wound care is wise regardless of the source of your skin breakage, be it a general abrasion, a spider bite or something else. I had a couple of general abrasions turn very nasty by not following my own advice and have the scars to prove it!

  2. Thank you for you well written and easily understandable article. My daughter, when a teenager took a great interest in all insects including spiders and would regain me with stories of white tail spiders, as I had never heard of them before, I was very skeptical. There doesn’t seem to be much information available about them. Your article has shed some very welcome ‘light’ on the subject.

  3. Thank you for the article but as someone who has been bitten – and have the scar on my lower leg to tell the story… I am a bit wary of them now. It hurt and became red and swollen and then infected. It took weeks of district nurse dressings and antibiotics (that did nothing) and finally it got smaller and less deep with manuka honey!

  4. Thank you for the article but as someone who has been bitten and has the scar to tell the story – it got red; swollen and infected that took swabs/dr’s visits/ antibiotics (that did nothing) and weeks of dressings from the district nurses … manuka honey finally worked it’s magic but as I say – I have the scar left on my lower leg. Am very wary of them now.

  5. Hi Phil
    I’ve been bitten by white tails many times – usually just put betadine and bactroban on the site and have only once had a reaction I couldn’t ‘control’ with these two agents (plus occassionally a hystamine tab to assist if the reaction calls for it). I encourage ‘Daddy long legs’ in my sleepout to lessen the numbers.

    I was under the impression that although their bite wasn’t particularly venemous, they are what is called a ‘dirty mouthed’ spider….much like the Australian Blue Tongued Lizzard, not having a venom that effects us, but that they can have nasty bacterium in their mouths (even necrotising)…is this NOT the case?

  6. Is there any truth to the notion that their venom is necrotising? (Not sure I’ve used the right term there) ie there is something in the venom that acts to break down cells and prevents wounds from healing?

  7. Hi, was just wondering if you are more likely to be bitten at night if you like your warm water bottle very much. I was bitten 3 times during sleep, the only one in the family and I think this could be the only explanation. Did not see the spider but I think it could be only that, I mean what else in New Zealand can organize you a blister overnight? Like a stage 2 burn? I might be sensitive but symptoms can be stronger and take longer to dissapear.

  8. I thought the issue with white tail bites was the risk of serious complications.

  9. The mason bees are doing there collecting as usual each summer. But we have noticed that at our back door we have a large colony of rather large white tails that seem to be feeding off the spiders placed by the mason bees. They are getting through a window into our daughters room by the tens. and they are never small. They look like a black and white wasp with legs! We don’t want to get bitten so will be bombing the back door soon unless you have other suggestions!
    Cheers!

  10. Thanks for this extremely interesting article. While not particularly dangerous to humans, Is it true that white-tail venom is particularly dangerous for household pets like cats and dogs? Do pet owners need to exercise caution when it comes to white tails in the home?

  11. So in other words…… Keep all the Daddy Long-legs you have in your house to help keep the white tails at bay? Also for the last few years we’ve noticed that every year in March is when we seem to get our yearly does of White tails inside the house. Is there anything about March or is that just a coincidence? We also get them come in, in pairs ?????

  12. Great article dispelling a few myths. So, if it’s not Whitetails causing those nasty wounds that are the subject of (frequent) media articles… what is it? I’m satisfied that Whitetail “venom” isn’t the problem but clearly some people have a nasty reaction to something. Any ideas?

    1. I had been bitten by a spider on the beach in Petone right in the foot. The bite was painful as I would step on to a thick needle. The foot become numb and the pain got stronger. In a couple of hours the foot swallowed and there were obvious two little holes of the bite. My kiwi husband recognized the bite as a White tail bite and we kept watching the symptoms. I put aloe Vera for a few hours and by the next morning the edema got less. The pain lasted for three days and then the foot become itching. The skin necrosis lasted over a month.
      I feel Aloe Vera helped me a lot to soothe the pain during these times.

  13. I also appreciate this. My question is are there any special considerations for children, especially small ones? I tell people that white-tails aren’t dangerous and they say that it’s worse for kids because of small body size. From what you have just said (pain of bite issue aside) it sounds like body size has nothing to do with it, but it would be good to know if the study you mention included young children.

  14. I was once bitten by a white-tail and it was like a bee sting, except slower: I could feel the venom creeping under my skin, which was disconcerting. But the pain and swelling went down fairly quickly, leaving me with a large bruise-like mark which disappeared after a day or so. No lasting ill effects.

  15. This is a great article. Its really good to set the record straight about white-tailed spiders and debunk some very common myths about spiders.Thank you.

  16. Thanks Phil. The truth will out! I can’t wait for my two daughters to get home from school so I can read this to them in an irritatingly told-you-so tone. They actually love bugs, and we once had a great time watching a whole spider’s egg sac hatch on their bedroom ceiling. But every now and then a blood-curdling scream of ‘ARRGHH – IT’S A WHITE TAIL!!!!’ echoes through the house.

    No more excuses for not helping to collect the wood in winter.

    PS If any parents out there want to turn very young arachnophobes into arachnophiles (is that a word?) I can recommend a gorgeous picture book called Sophie’s Masterpiece. The author’s name is Spinelli, I kid you not.

    1. Sophie’s Masterpiece is gorgeous and I add my recommendation!

  17. That was a really enjoyable and informative post Phil. I was one of those idiots who believed the daddy long-legs story. I can stop running away from them now.

  18. Thanks for this. Lots of people are very scared of white tailed spiders so its great to get an article like this written about it. The information about the other spiders was very interesting as well.

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