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Man throws midge off the scent
Scotland On Sunday 06/05/07
THE mystery of why midges eat some people alive and leave others largely unscathed has been unlocked by a team of Scottish scientists.
A cocktail of eight chemicals naturally secreted by those fortunate enough to be immune to midges has been identified by the researchers as the key.
The scientists have no clear idea why the chemicals work as repellents but the very fact they do could lead in the near future to a highly effective anti-midge cream. The team from Aberdeen University have already patented their discovery in the hope of earning a fortune.
The potential breakthrough in battling culicoides impunctatus, to give the midge its scientific name, could also have major implications for the Scottish tourist industry. The most midge-infested areas of Scotland contain an estimated 50 million insects for every 100 square metres of land. Recent research showed that almost 90% of visitors to Scotland would caution friends not to come north of the Border in July or August because of the insects. It has long been suspected that a minority of individuals enjoy a form of natural immunity to the midge and the £150,000 study examined more than 300 chemical compounds found in sweat and body odours, many of which cannot be picked up by the human nose.
One experiment involved getting a volunteer to wear women's tights on their arms, with different combinations of chemicals on the left and right. The numbers of midges which landed on each arm were analysed and over time the key chemicals could be isolated. The team have narrowed the field to eight. Further research is needed to establish which of the eight are the 'magic' ingredients.
Professor Jennifer Mordue, who led the project, said she was unable to go into detail about the chemicals because of commercial confidentiality.
She added that it was unclear whether midge-resistance ran in the family or could be linked to any other genetic traits, such as eye or hair colour. She said: "It's a fascinating question, but it would require more research to answer."
Helen Todd, of the Ramblers' Association Scotland, said: "We would be delighted if anybody did come up with a solution for the midges. If this meant that more people could get out and enjoy the countryside then it would be very welcome."
Midges are a particular trial for those working outside in the Highlands and Islands. One study has suggested that as many as one in five working days in forestry is lost as a result of feasting midges.
Royal Marine Commandos famously use an Avon skincare product, Skin So Soft dry oil body spray, to repel midges.
Midges also detest pipe and cigarette smoke, and one unforeseen effect of the smoking ban is that midges have begun heading inside pubs, bars, and restaurants.
A study carried out by Edinburgh University in 2002 suggested that as many as 86% of visitors would warn their friends not to visit Scotland during July and August because of midges. However VisitScotland says that just 2% of tourists cite midges as a drawback.
Of the 30 different types of midge in Scotland only the female Highland midge bites, with its tiny saw-like teeth, in order to get the blood it needs to feed its eggs.
The midges find their prey by detecting minute variations in carbon dioxide and then homing in. They actually prefer feasting on deer to tormenting humans, and suffering deer avoid midges by going as high as possible in the mountains. Midges dislike being too high up in the hills.
One popular trick for avoiding being eaten alive while working outside in the Highlands on peats and hay, is to stay as close as possible to a pipe or cigar smoker. Citronella oil in candles and tea tree oil are also popular repellents. Some say eating lots of Marmite in the weeks before you go to midge-infested areas helps to create a smell which wards them off
