One of the services offered by exterior cleaning companies such as The House & Building Wash Company is spider treatments—but why, you might ask, are these treatments necessary? In New Zealand, we have many species of spider, most of which are harmless (if creepy) and perhaps even handy to have around due to the fact that they catch and eat pest insects such as flies and sometimes wasps. There are only three species of spiders in New Zealand whose bite can cause harm to humans: the katipo, the redback, and white-tailed spiders.
Katipo, which are native to New Zealand, and redback spiders, which came here from Australia, are both exceedingly shy and non-aggressive, and though their bites are venomous, they’re also extremely uncommon. White-tailed spiders, however, are a different and considerably more pertinent story.
In this blog post, we’ll discuss white-tailed spiders, the myths and facts surrounding them and their bite, and how you can keep them away from your home with an exterior spider treatment.
What Are White-Tailed Spiders?
Like the redback spider, white-tailed spiders originate from Australia—and similar to how the redback spider is so named for the red markings on its back, the white-tailed spider is named for the white, tail-like marking on the end of its abdomen. White-tailed spiders are common in New Zealand, especially in the north island, and can frequently be found in houses, a good source of food and shelter.
Something interesting about white-tails is that, unlike most spiders, they don’t build webs; they’re nocturnal hunters who actively prey on insects and other spiders, which is what often leads them into our homes, where they can find ample hiding spots and a steady food supply—including those more harmless household spiders such as the daddy long-legs.
The White-Tailed Spider: Fact vs. Fiction
As one of the only spiders in New Zealand capable of biting humans, white-tailed spiders have garnered a villainous reputation, largely because of their bite, which is believed by many to contain a necrotic venom that induces serious infection. In fact, the owner of The House & Building Wash Company, Mark Ridling, has his own experience with a white-tailed spider bite that resulted in septicaemia and a hospital stay—quite ironic for the owner of a company offering spider treatments, we know! If you're feeling brave, click here (at your own risk) to see the photos of the bite... but be warned, it's pretty gnarly.
It may be the case, however, that white-tailed spiders get a bad rap for crimes they never committed—at least not directly.
White-Tailed Spider Myths
There are a couple of common myths surrounding the white-tailed spider, myths that (quite rightly, nonetheless) encourage us to be cautious of them:
Myth No. 1: White-tailed spider venom causes necrotising arachnidism (i.e., ulceration and tissue death around the wound site).
This is, despite popular belief, not true! A prospective cohort study from Australia investigating 79 confirmed white-tail bites over the course of three years found zero cases of necrotic ulcers or infections. Pain and discomfort occurred in all cases, redness and itchiness occurred in most, and, in very few cases, there were systemic effects such as nausea and/or headache. But that’s about it—suggesting that the necrotic ulcers apparently caused by white-tailed spider bites actually come from a secondary cause.
Myth No. 2: White-tailed spiders eat daddy long-legs spiders and confer the latter's venom into their bites, which is what makes them necrotic.
This is a few myths rolled into one, the only true part being that white-tails may occasionally eat daddy long-legs spiders—though it’s just as true that a daddy long-legs could eat a white-tail, if one got stuck in its web. However, while it’s commonly believed that daddy long-legs possess a severely poisonous venom but lack fangs capable of puncturing human skin, daddy long-legs are actually completely harmless. Therefore, when a white-tailed spider eats a daddy long-legs, the only outcome is that the daddy long-legs meets an unfortunate end and the white-tail gets a lean-legged meal.
So Why Are White-Tailed Spiders Such a Big Deal?
If white-tail bites cause little more than a bit of pain and itchiness, doesn't that mean there's nothing to worry about? Well, despite study results and lab evidence showing that white-tailed spider bites can’t innately cause necrosis or infection, the anecdotal evidence of hospital visits from white-tail bites is overwhelming. Take Mark, for instance.
According to an article from NZ Herald, there are around 300 ACC claims per year for white-tailed spider bites. Most of these claims are to cover medical bills for allergic reactions or infections occurring as a result of the bite. In a particularly notable case in March of 2024, a bite from a white-tail left a Palmerston North man unable to walk for a month when the infection migrated to his leg.
The truth, it would seem, is somewhere in the middle. While it’s true that white-tailed spider bites aren’t inherently life-threatening, the fact that they break the skin creates a vulnerable entry point for secondary infection (i.e., an infection resulting from a source other than what caused the wound).
The real enemy? Bacteria, of course. Bacteria such as staphylococcus, which is commonly found on human skin, can cause horrific and at times even deadly infections. This—not the spider bite itself—is to blame for the adverse white-tail bite reaction that we all know and hate. In particular, since white-tailed spider bites can cause itchiness, this might lead us to scratch at the bite, introducing bacteria from under our fingernails, which are known to harbour a thousand times more bacteria than other areas of our hands. Scary stuff!
Exterior Spider Treatment: Prevention is Better Than a Cure
While it’s true that a while-tail bite is unlikely to cause you any great harm so long as you take due precaution to treat and sterilise the wound (and avoid scratching it), they are still painful to deal with, and the possibility of a secondary infection or allergic reaction is always there—not a risk most of us are particularly willing to take with ourselves, our family, or even our pets. The best way to keep a stranger out of our home is to not open the door, and this is the same with bacteria and our body: a white-tail bite is open door for infection to wander through.
So, then, much like a home security system will deter burglars, an exterior spider treatment might just be the precaution that keeps white-tails, their bites, and the risk of infection far away from you, your home, and your loved ones. Though the treatment is non-discriminatory and will eliminate and deter all spiders and insects caught in its path, this has the subsequent effect of preventing white-tails from coming over. As already mentioned, they tend to prey on other spiders that build their homes on our homes, so keeping your house clean and cobweb-free is the best way to discourage them.
The exterior spider treatment offered by The House & Building Wash Company has a fast knockdown and kill rate and is guaranteed to last for six months. It has no detectable odour, low-toxicity, and is non-staining, leaving no visible residue on walls. Our technicians are trained and certified in the use of controlled pesticides and the necessary protective equipment. First, we wash away the cobwebs, and then we make sure they won’t be back for a while—easy as that!
In these warmer months, spiders and insects, especially white-tails, are out and about and you’re much more likely to encounter them, making now the perfect time to act. If you think your home could benefit from a house wash and exterior spider treatment (not to mention the range of exterior cleaning services we offer), don’t hesitate to get in touch—we won’t let the white-tails bite (not again, at least)!
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