Friday, 30 April 2010

Dragons in Paradise: Part 2


[A model sandfly at Milford Sound, NZ. Be thankful they don't come this big in real life!]

[more musings on things that sting and bite in several different countries]

At the other end of the size scale of "dragons" is the humble New Zealand sandfly. Actually sandfly singular is an oxymoron in two senses. Firstly you never see just one: clouds seems to be the preferred collective. And secondly there are about 13 different species of sandflies. The slightly good news is that only two of those species – and then only the females – actually bite humans. However species and gender identification of sandflies is an arcane business, and few trampers have mastered it. Another possible comfort is that if you climb to 1500 metres, and stay there, you will not be troubled by sandflies.

If lack of altitude or entomological expertise means you do come into contact with these little beasts, locals will assure you that sandflies are not generally lethal. Despite such reassurances, experience will teach you a “once bitten twice shy” kind of lesson. Despite being visible, sandflies are very small, and usually silent, unless one happens to fly right into your ear. If they evade your attention they will typically land on a nice piece of exposed skin, say around your wrist, ankles, neck or face.

Their bite is scarcely noticeable – at first – and they are usually long gone with their load of blood before you know about it. But they will have left their little chemical calling card: an anti-coagulant that helps your blood to flow. That in turn will set up an irritation that means the bite swells slightly, your immune system’s automatic response to the chemical invasion. Your slightly more conscious reaction will be to scratch the itch: not a good move, but one that is hard to resist. In my case the tiniest of bites on my wrist became so itchy that I scratched it in my sleep.

The bite then became infected, probably from bacteria that were already present on my skin. The infected bite then swelled more, reddened further, then darkened to an ugly blotch. Over the next few days it became even more maddeningly itchy. Eventually – maybe two weeks later – my (mere Aussie) immune system got the better of the bite. The fearful thing is that this was ONE bite. It is far more usual to receive multiple bites. In the poor German tramper’s case (see "Dragons in Paradise: Part 1"), his immune system had a long and hard struggle to overcome the dozens of bites, and permanent skin scars may well result.

 
By now you may well be wondering how you can avoid this hell-on-wings. For instance have the ever-inventive Kiwis come up with a bear bell equivalent: perhaps a sandfly siren? Well no, so far they’ve not, although they do offer a plethora of sage advice. A good start is to starve the buggers of exposed skin by wearing long sleeved shirts and trousers and a hat. Next you can put insect repellent on any exposed skin and on your hat. One I didn’t try, but which locals swear by, is to take vitamin B tablets. Apparently sandflies don’t like this, and as those great Australasian delicacies Marmite or Vegemite are full of it, some recommend large doses of this. If sandflies don’t like vitamin B, they DO like dark colours, so it’s best to avoid wearing black, navy and similar coloured clothing.

There’s a kind of “my father’s tougher than your father” debate between New Zealand’s sandfly fanciers and Scotland’s midge admirers. In Scotland there are around 30 different species of midge, but only one that is a real bother to humans. Culicoides impunctatus failed to make an impact during my couple of weeks in the Scottish highlands a few summers back. I was almost disappointed, given that I’d purchased some special insect repellent and a rather fetching khaki midge net that looked like an oversized gauze condom.

Scots tried to soothe me by saying things like “och, if ye’d only come last week …”, a phrase they usually saved for the weather. As with weather, you can now get a summer midge forecast in Scotland. It’s totally serious, and is based on a combination of counts from midge traps and expected weather conditions. You’d have to imagine that’s one up on the Kiwis.
I imagine a play-off between these two fearsome critters. The sandflies would do a haka, of course, and the midges would be piped onto the field by a band playing “Flyers of Scotland” (a special Diptera version of that Scottish national song).

If it wasn’t for our leeches, jack jumpers, march flies and mosquitoes, I might almost feel as though Tasmania was left out of this invertebrate face-off.
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