The hunt for weapons of midge destruction

Another Life: Sparrows hover like hummingbirds to peck midges from the windows, their tappings gentle and precise. Swallows from the woodshed swoop like Poe's pendulum, scything through midges in the gap between the oaks. Our bats, no doubt, take their toll each evening: they have merely to open their mouths, like basking sharks at plankton swarms (yet have you tried to catch, one-handed, the midge determined to share your bedtime book?).

None of this natural predation reduces my torment, kneeling to weed the seedbed or set out the Brussels sprouts on a suitably sunless, moist morning. Each year, it seems, I try out some new unguent that is not based on DEET or DMP, plastics industry chemicals proved on the hairy arms of American drill-sergeants.

This year's herbal cocktail is an "extreme repellent" from Scotland where you'll find the most rapacious midges in the world. It takes oil extracted from the seeds of India's remarkable neem tree, which repels locusts, boll weevils and a hundred other insects, and blends its distinctive scent with that of traditional anti-midge fragrances.

Citronella, derived from a tropical lemongrass and once supplied to forestry workers in gallon jars, is joined by oils of orange, lemon, lavender, peppermint, wormwood, camphor and more, all decked out on the label in their botanical Latin names. Yes, but does it work? Quite well, actually, with proper attention to the folds of the ears and eyelids and soft hollows of the clavicle; try not to sweat from the temples, that fatally tender pulse.

I am unfortunate in the matter of midges: veterans of this column set the season by my complaints. Are there really others in the world, blessed souls whom the insects "never bother"? Biologist George Hendry of Aberdeen University, centre of decades of midge research, tried to set the record straight in his little book Midges in Scotland, now in its fourth edition.

First-time visitors to midge country, he explains, enjoy a sort of honeymoon period in which the bites of blood-seeking females have no noticeable effect - this because human immune systems take time to recognise the alien proteins in the midges' saliva and develop antibodies to them.

After three or four days, however, the body's defences are mobilised, pumping histamine into the wound to detoxify the midge saliva and calling up white blood cells to disinfect and repair it. This essentially healthy process is what produces the irritation and the swelling.

Years of bites can slow the reaction to more tolerable levels and some people react more severely than others. But it also seems likely that people do, indeed, vary in their pheromonal attraction.

Beyond the misery and lost productivity of foresters, farmers, vets, linesmen and many others, the economic impact of biting midges on the tourist industry has focused scientific minds on the development of weapons of mass destruction. Spraying insecticide from the air has small effect - midges, unlike mosquitoes, take refuge on the undersides of leaves. Spraying larvae at moorland breeding sites needs persistent insecticides that kill indiscriminately and build up in food chains. Neither strategy could contend with the wind-drift of midges that repopulates cleared areas, or brings them from moorland into the heart of small towns.

Now it is the turn of new propane-fuelled machines that, in one description, "cross a cow with a vacuum cleaner". They draw female midges from 100 metres away with gusts of carbon dioxide and other mammal-like attractants, then suck them up into a net, where they die of desiccation.

During her four-week life-span, a female can lay 300 eggs, so that catching 1,000 a day eliminates 300,000 potential offspring and the aim is to collapse local midge populations within some two months of continuous use.

America was first on the market, with machines designed mainly with mosquitoes in mind. In trials at Powerscourt Waterfall children's playground in the summer of 2003, a single Midge Magnet Professional machine from American Biophysics (costing round €2,000 and protecting about one acre) was estimated to have trapped an average of 88,000 midges a day for 80 days.

Its big rival in these islands is Calor's Midgeater Plus, developed at Edinburgh University's Centre for Tropical Veterinary Medicine and designed specifically for the Highland (and Irish) biting midge Culicoides impunctatus and her vicious Culicoides sisters. It has, I am promised, "more sucking power" and, at less than €1,000, competes with the middle range of American machines, aimed at beer gardens, visitor centres and the more affluent of private patios.

With running costs for bottled gas and attractant refills, such gadgets are beyond my pocket. I also gaze up to the miles of mountain bogs above my acre, from which strong, pipe-puffing men have fled in my memory, and wonder if, in the end, it wouldn't be like putting our dehumidifier out of doors to dry the sky.