Wednesday, 11 June 2008

The Highland Midge


In most parts of the country the weather tends to be the first item of a conversation - irrespective of whether it is between friends, acquaintances or complete strangers. On the Isle of Lewis there is an equally popular alternative - midges.
The female Highland Midge (Culicoides impunctatus) is a vicious little so-and-so that bites while both sexes can fuss around one's eyes and ears and mouth and generally annoy one.

It is known in Gaelic as meanbh-chuileag (tiny fly) and, as it's Gaelic name suggests, it is very small in size, with a wingspan of about 1.4 mm., a body length of slightly less than that and a weight of about 0.5 microgram. The transparent or membranous wings contain six or seven dark blotches and these form a distinctive pattern which differentiate the Highland biting midge from closely-related species, such as the garden midge (Culicoides obsoletus). When it is at rest, the midge's wings are positioned over its back, with one wing on top of the other.

In one study, 500,000 midges were collected, emerging from an area of just 2 metres by 2 metres. On that basis, a space the size of a garden barbecue area may have more than 1 million midges. That's enough to spoil anyone's party!

Allegedly, at wind speeds of over 8.8 kilometres per hour (5.5 miles per hour) midges are unable to fly, and will land on ground vegetation. Unfortunately the midges on Lewis have not read this piece of research and tend to fly when the wind is quite a bit stronger!

After fertilisation the females require a meal of blood for the eggs to develop fully. This bloodsucking, or haematophagous, behaviour involves feeding on mammals, typically red deer (Cervus elaphus) or cattle, and, to a lesser extent, sheep. Other mammals, including humans, are fed upon when the opportunity arises.

Research has shown that, in her quest for blood, the female midge is attracted to dark-coloured moving objects, particularly where they are associated with carbon dioxide, which is given out in the breath of mammals. In addition, the midge has a well-developed olfactory sense, which it uses to detect the presence of several chemicals in the body odour of humans and other mammals, such as acetone and lactic acid.

Once prey has been located, the midge cuts through a soft area of skin with specialised mandibles and mouthparts. The mouthparts are then rolled into a tube and inserted into the wound, to suck up the blood. If the midge is undisturbed it will drink for up to 4 minutes, by which time the abdomen is distended and swollen. When she has found a blood meal, the female midge releases a chemical called a pheromone, which acts as an attractant to other females. This leads to mass attacks, involving hundreds or even thousands of individuals, at the height of the midge season in July and August.

Midges are crepuscular in their behaviour, meaning that they are most active around dawn and dusk, when light levels are reduced. Light is the most significant environmental factor for their biting activity - on a bright sunny day, few midges may be encountered, but on a dull, overcast day, substantial numbers may bite, even in the middle of the day.

Sadly, although it is so numerous, the Highland biting midge is not a major food source for any insectivorous animals or birds.

In parts of the Highlands it has been estimated that up to 20% of the summer working days in outdoor jobs such as forestry are lost due to midge attacks. Even a simple task such as tying bootlaces becomes impossible when midges are at their worst. For the summer months of the midge season, this miniscule insect, by dint of its biting habit and sheer numbers, is a dominant factor in life out of doors in the Highlands and Islands, causing significant changes to human behaviour. There is a positive side to this though, as the midges have undoubtedly contributed to keeping the north and west of Scotland sparsely populated, and therefore as wild as they still are today.

Culicoides midges of one sort or another are found throughout the world but one of the few places they are not present is New Zealand - which could explain why GB finds it so attractive to go there for his other summer.

For further information the brilliant book 'Midges in Scotland' by George Hendry is a must.

Now the important bit - how to combat them.

Two chemicals in common usage in midge repellents are DEET (Di-ethyl toluamide) and DMP (Dimethyl phthalate). Eureka is a well tried repellent which contains Geranium and Lavender. Bite Free, from the same manufacturer, is another repellent and has citronella, lemon grass and eucalyptus amongst its ingredients. Avon's Skin-so-soft body oil (in spray-on form) is also said to be very effective for some people.

Another herbal repellant, whose principal ingredient is Bog Myrtle, is available from

Some people dab a little vanilla extract on their wrists, neck and behind the ears. Rubbing a lavender flower in the same areas is also said to help.

It seems to be a matter of personal preference - perhaps related to one's own body chemicals and behaviour - as to which has the best results. Another recipe is to mix witch hazel with a few drops of tea tree oil, lavender oil, or peppermint oil in a squirt bottle. Lightly mist your body. You can also add one of these essential oils to an unscented organic lotion for a bug repelling moisturizer.

By far the most effective safeguard against the midges is a midge hood made of netting and these are widely available nowadays, as are full midge suits. At one time no 'real man' would have been seen dead in a midge hood or midge suit but common sense (and the midges) have prevailed and they are now quite popular not only with tourists but with islanders as well.

Wearing light coloured clothing is also said to help but at the end of the day - "The Midges Rule - OK!".

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