Folklore remedy may lift curse of the midge

Scientists are testing a new weapon in the ancient war against a tiny creature's bite. Stephen Goodwin reports
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The Independent Online
A muggy evening in the north-west of Scotland and the Curse is visited upon all those with the misfortune to be caught out of doors. Culicoides impunctatus, or at least the female of the species, is after a blood meal and a droplet of tourist, camper, rambler or climber would go down very nicely.

The Curse is the midge, a tiny creature with a reputation as formidable as its ability to reproduce in vast numbers. In the midging hours, early morning and around dusk, campers swathe themselves in tea towels or other protective headgear. Elsewhere, windows are shut.

But relief may be at hand. At a university research centre on Kintyre, one strand studies the creature's behaviour while the other two offer the prospect of relief from its attentions.

The centre - a cottage provided by the Ormsary Estate with a laboratory in an adjoining shed - was set up by Professor William Mordue of Aberdeen University zoology department. "These females are after your blood," Professor Mordue said in a layman-friendly summary. "They are attracted by those nice little smells we pretend we do not have and, of course, our breath."

A key to the success of Culicoides impunctatus is that unlike many other biting flies it does not need a blood meal to start laying eggs. It will only take one ten-millionth of a litre of blood. What irritates for days is not the bite but the anti-coagulant saliva it injects.

For the last three midge seasons - May to the end of August - Amit Bhasin has been trapping, collecting and counting on the estate in a PhD study on host-seeking behaviour - looking at what chemicals attract the midge. He has mimicked the cocktail of smells given off by cattle and deer and tested them with and without the crucial ingredient of carbon dioxide.

The numbers of midges attracted in their favourite boggy territory is staggering - a 10-minute test last year with a carbon dioxide flow rate of one litre per minute lured 15,000. Students are acting as guinea pigs for work on a natural-based repellent - the big hope of the Highland tourist industry.

The warnings on many chemical-based repellents have been off-putting. The user's glasses along with other plastics were in danger of being melted. Yet these potions were to be applied to the skin. Less frightening products have been developed but the unease remains.

Now Dr Alison Blackwell, of Dundee University, and a team of students are conducting tests on a cream containing oil from bog myrtle - Myrica gale - which could provide a natural repellent and welcome jobs on Skye.

On a midge-rich evening, Dr Blackwell's students will stand outside, masked and covered except for one bare forearm. Some arms will be smeared with the repellent - added ingredients are also being tested - but someone must act as a control with no repellent at all. The idea is to count how many midges land and how many bite.

"Human baiting" is the term. Fiona King, who now helps Dr Blackwell, said: "Last year I got 200 bites in 10 minutes."

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