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

43 Comments

  1. I question the value of the report mentioned by the author as the study is out of date and has questionable value when real doctors and nurses are constantly treating the effects of white-tail spider bites. Maybe the author would care to review this article with some real-life data from hospitals and comment?

    The doctors and nurses that treated me for my white-tail spider bite in hospital found this article laughable as they find white-tail spider bites almost always get infected and white-tails should not be underestimated

    My own personal experience of white-tail spiders wasn’t pleasant, the bite site quickly went red and swelled. This article lead me to believe I was only dealing with some localised redness and swelling. A couple of days after being bitten I sought medical attention but by then local antibiotics could not get the infection under control. I was admitted to hospital for I.V antibiotics and surgery as the doctor feared the infection had spread to my blood and I was close to septic shock.

    1. Author

      Dear Russell,

      From the blog post:

      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.

      Nobody is claiming a white tail bite cannot be subsequently infected. Literally any wound can be, but there’s also no good evidence to suggest white tail bites are more likely to become infected either.

      Medical diagnoses of white tail bites are unreliable without direct proof like an identified specimen or a clear sighting of the spider in the act of biting. The symptoms of white tail bites are simply not distinct enough to allow a clinician to say definitively that a white tail is responsible. Presentation of an infected wound is not necessarily proof of anything other than an infected wound, yet there are case studies that show that white tail bites are sometimes assumed to be responsible where other causes were later correctly identified. I assume you saw the spider in your case, but it’s pretty clear that in both Australia and New Zealand, white tail bites are sometimes blamed for symptoms where no spider is involved at all. I’ve even heard of diagnoses of white tail bites on the basis of infected wounds being presented and a white tail was seen several days later! I’ve been told by medical students that they get very limited training in bites and stings in the New Zealand system, which makes some degree of sense given the disease burden from these is comparatively low. This is not to trivialize the real suffering people might experience, but the diagnosis of a white tail bite without good evidence is a diagnosis of convenience rather than one of certainty.

      In contrast, the Australian study is robust as the cases all have verified evidence of white tail responsibility and is of a sufficient size to draw meaningful conclusions. The age of the study is not especially important here as it’s not as though the biology of the spider would change markedly in the time since then.

      There is no evidence that white tails routinely transmit pathogens when biting, but like any skin breakage, a white tail bite can allow infection in at the time of the bite or later. There’s nothing unusual in that as the infectious agent may already be living otherwise harmlessly on skin surfaces in close proximity to the bite, or picked up later on from the environment. ANY wound, be it a bite or something else, should be given all due care to minimize the risk of infection. Even then, someone may be unfortunate. You certainly were, as was I with a graze that I thought I’d looked after well enough but it got infected, took months to heal and has left me with scars I carry to this day. Infection of wounds, no matter the cause, should be the real concern here, but beyond creating an entry point, white tails don’t appear to be anything to be especially worried about.

      If white tails really were dangerous, I like to think someone would have shown that unequivocally in the 150 or so years they’ve been present in New Zealand, or in Australia where they are native. The initial concerns about this spider arose when it was suggested that white tail venom was capable of causing necrosis (tissue death). However, studies of the venom show that’s not true.

      If you have further questions, you’re more than welcome to ask.

      Kind regards,

      Phil

    2. I agree Russel, I’ve had two white tail bites within 6 weeks and both were really bad, antibiotics couldn’t help it so had to be put on I.v twice for the first one, then have surgery to cut it out. The second one I went in quickly and they put me straight on iv antibiotics and cut it open to get the stuff out. I think I’ve just had a third one too so expecting the worst

  2. Wait right now I’m in bed and a big ish white tale ran across my finger and if your saying that they put there webbing on there prey then bite does that mean it was going to attack me because i had some webbing across my hand

  3. A few years back I was working as a laborer for a builder. We were renovating a batch. I got bitten by a white tail . The next day i had what looked like a pimple on my right ring finger…I popped it squeezing out the puss….the next day it was back and three times the size…long story short…had to get my finger lanced three times by doctors…the flesh around my bone had all but dissapeared I could see my bone in my finger….the smell was horrible and my hand was twice the size of my other hand from swelling….so…if it wasn’t the venom of the spider that caused all that…what kind of bacteria eats away flesh and muscle?…

  4. My son was bitten by a white tail while working in the bush. Next thing he knew he woke up in hospital 2 days later. He stayed in hospital for over a week on IV antibiotics.
    Another friend is allergic to them and is often bitten by them. She has found them in her bed. She ends up with boils where the spider has bitten.

  5. Whomsoever claims that White Tail bites aren’t venomous, I believe, has a bias in that they do not want to see these sneaky biters labeled “poisonous”.

    I was a beekeeper for some years, I received my share of stings and I know venom when I am bitten. In my 9 years in my current home I’ve now had at least 50. It’s a modern home, I use no poisons and I get paid for it in bites that aren’t felt at the time then, they turn itchy, then swell, then blister and persist for over a week. I am considering starting “World War White Tail”…..really….I feed bees. THEY don’t sting me. I sit down at my own deck table and out they come. You folks need to review and revise what you’re advising people because the White Tails are persistent, silent, sneaky and aggressive when no provocation has been made toward them. My take on them? They territorial….let them buy their OWN deck furniture….

  6. I really like this blog,please write some more!

  7. Hi, I was wondering if baby white tails can bite/break the skin.
    Over the past few mornings I have woken up with very itchy red swollen bites on my body and on searching the bed all I could find was a baby white tail walking across my pillow

  8. Thanks for the article Phil dispells alot of the information I was originally given. Can you please clarify some more for me please. Is it true that only the females are venomous and that they are only venomous during certain months of the year i.e Summer time and that they are the only spider whose exoskeleton does not grow with it and therefore has to shed its skin several times during its life. The exoskeleton comment rings true I’ve seen sometimes quite big pink fleshy type spiders. Might they have been white tails that have just lost thier exoskeleton.

  9. I’ve copped two bites a month apart. Had swelling around eye with first one but the second one has given me extensive swelling. Was at eye clinic a couple of weeks ago and my doctor told me that they can affect the eyes. Has anyone else found this

  10. I have just been bitten 4 hrs ago, its dam aching sore & hand stiffening up ! i am a beekeeper, wasp hunter & this is worse & much longer lasting hurt! & getting worse! Its a whitetail alright I saw it..too late! would be nice to have a few tips on treatment ! bloody hurts.

  11. As a victim. of a white tail bite, I beg to differ on its potentiality,I’ve been bitten by redbacks, twice, a a Huntman, wasps, bees, with little effects, however, I was bitten on the shin by a white tail, I cleaned the bite area, it still swole and was extre.Ely itchy, I took an antihistamine, within eight hours my lower leg had swollen, by the next morning I couldn’t walk on it, I wss taken to Kiama .Medical Centre (NSW Aust.)
    Because of my condition being so serious they tried to contact an anesthesiologist to no avail, they said that It needed it to be lanced open immediately, I I had to sign a amputation form permitting if it was required to save me, they strapped me down and proceeded, my screams were heard 3 wards away from theatre, they drained 2 litres of pussy liquid from the hole inside my leg, my heart stopped twice, for the next three weeks my leg was drained, cleaned, and packed until it had healed over.
    That White Tail nearly killed me, so the assumption they are not deadly is a myth, a spider expert in Sydney told me, the danger is in the fact that The White tail is feral and does not always clean its fangs, which then transmit bacteria that infect and eat the flesh, I have heard since the same.e thing happened to others.

    1. Hey I’ve been bitten on my hand by white tail was really itchy at first then few hours later was really sore hand started swelling and the pain was aching want to the doc for meds it was full of puss and my hand was fat

  12. I have been bitten by a white tail in bed at night out the back of Henderson surrounded by bush. It has caused me no end of problems. Started off as a small painful like pimple (bright red – lump wasn’t there when I went to bed) I plastered over it and thought nothing more of it. Within 12 hours I was having to be assisted walking and spiked a fever of near 40 degrees. It left me with MRSA (hospital superbug) dead flesh and muscle and long term reactive arthritis along with a permanent scar on my right calf the size of an old 50c peice. Good or not all spiders I see now die

  13. I think I might have been bitten by a spider – sharp pain like a needle in the back of the leg when I got into bed. Couldn’t see a spider but had about four small square bumps leading from what looked like a small red pimple and the leg was pink in the surrounding area. However I was in Lower Hutt over Christmas where an elderly man in the street was bitten by a white tail and had to spend two nights in hospital. He also mentioned an elderly relative who was bitten by a white tail and died. So maybe it has a worse effect on the elderly.

  14. Been confused for a while about exactly what a daddy long legs is.There’s those ones in the garden that just run about and make no web and there’s those ones you find often in the laundry that make webs.Are they both daddy long legs?

  15. I have just been told the daddy long legs “myth”! Thanks Phil! So glad I found your blog. Can’t wait to put that particular myth to rest with the person concerned

  16. @Marina Graham if you were bitten by a spider at the beach with those symptoms its actually more likely that it was our own native Katipo. They have a potent neurotoxin and an extremely painful bite, though bites are extremely rare due to both their shy nature as a member of latrodectus (widow spiders) and due to their small populations (they’re endangered). Their primary habitat is beaches, specifically the long grasses near the beach. Its very difficult to establish which spider has bitten you from looking at the bite, hence the whole issue with people claiming spider bites for many common infections from cuts and the like.

  17. I have also been bitten by a White Tail and had a very nasty reaction that need intravenous antibiotics to treat. It was not only extremely painful at the time but the pain lingered for at least a week and the wound that the bite left went fluro green and putrid!! I’m not saying that they effect everyone the same way but I truly believe that some people are more sensitive to the venom than others and that I am one of them so i now refuse to go anywhere near the horrible little things.

  18. 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!

  19. 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.

  20. 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!

    1. Did that really help. I’ve just been bitten. Caught the white tail too

  21. 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.

  22. 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?

  23. 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?

  24. 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.

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

  26. 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!

  27. 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?

  28. 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 ?????

  29. 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.

  30. 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.

  31. 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.

  32. 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.

    1. This article has really helped me to understand White tail spiders more.

  33. 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!

  34. 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.

  35. 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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