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One of the perplexing events of recent years has been the explosion of reports on white-tail (or white-tailed) spider bites. It’s perplexing because the spider has been established in NZ since the late 19th C and the sudden leap in biting cases is rather extraordinary. I was initially confused when people started asking me about white-tail spiders. Alas, I didn’t know that they’d acquired this common name- only knowing them by their scientific name. I’d been around and handling white-tail spiders for decades it seemed, unaware of their fearsome reputation.



There are however, two important aspects of spider bites. First, most of the public cannot identify a spider correctly (the photos above should help). The second is that doctors are very error-prone at identifying spider bites. When I was at Waikato, a student of mine presented a medical certificate test for a missed test. I was intrigued to see it listed a spider bite as cause of illness. The student told me it was a katipo bite. I expressed sympathy and asked if she’s been bitten near Raglan. She said that it happened in Hamilton. I said that wasn’t possible. But she was sure that was the case because the doctor had said it was a katipo bite. Nevermind that katipos are only found on beach margins and never inland.

The parable is that when people present doctors with affected bites, lumps or scratches, doctors just diagnose the popular poisonous spider of the time. In the 1980s, that meant katipos. In the 1990s and beyond, that means white-tail spiders. They’re not making diagnosis, they’re just naming the only slightly dangerous spider they know of.

We should be clear that a katipo- as a good member of the genus Latrodectus is in fact venomous to people. White tail spiders are not. The Medical Journal of Australia cites a study on 130 confirmed white tail spiders bites where of course, nothing happened. No necrotic ulcers, no confirmed infections. Despite that, internet rumours keep the white tail up there as one of the most dangerous spiders in Australasia.

All we really know is that if you turn up to a clinic with a scratch from gardening, insect bite or even spider bite, it will probably be blamed on a white-tail spider. I guess it’s good for pest-eradication firms.

If there is such a break in your skin, and you are working in a dirty environment, there is always a risk of infection. Roughly speaking, 5g of dirt will have around 3000 species of micro-organisms. Most of these are unidentified and we don’t know what they do. If you get a bite or scratch or some kind, you should do what our grandparents used to. Make sure it’s cleaned and get some antiseptic cream on it.

White tail spiders are vagrant spiders. They don’t use a web, and they’ll often end up in houses. They have poor eyesight (as indicated by the photos above), and may respond aggressively if surprised. But the bite- even if lucky enough to break your skin- isn’t going to put a venom of note into you. Keep some antiseptic cream on hand, and if you can, catch and keep the spider that bit you for a proper scientific identification.

Just remember, Ive been handling these guys for decades. There’s not really anything to be worried about. Spider species don’t suddenly lie dormant for decades and then embark on a frenzy of biting people. The white-tail bite frenzy that seems to have gripped the nation is largely one of misdiagnoses. I suppose the only good thing is that it has let the katipo off the hook…