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45 Facts About the Highland Midge by Dan Aspel

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45 Facts About the Highland Midge by Dan Aspel

A midge swarm on the otherwise beautiful Isle of Rum.

It’s difficult to overstate the irredeemable nastiness that is the highland midge. Swarms of them plague the Scottish wilds throughout the summer, as inevitable as the tides, as merciless as time, as insidious as poison. They’ll make your blood boil if you let them (and then they’ll drink it). To anyone keen to explore the outdoors between June and September they’re more than slightly irritating. But that doesn’t mean they’re not fascinating too. For this blog post I thought I’d hit you with a fact blitz about these notoriously vile creatures, and finish it off with a little advice on how best to protect yourself from them before winter comes and cleanses the landscape once again (aaaaahhhhh).

Here we go…

There are 152 species of biting midge in Britain - most of which feed on other insects.

… but 50 feed on warm-blooded animals.

… 37 of which occur in Scotland.

(biting midges can also be find in the wilds of North Wales and northern England)

The highland midge is known as Culicoides impunctatus

The enemy: culicoides impunctatus in the (on the) flesh.

Its Scots gaelic name is meanbhchuileag (trans: “tiny fly”).

It has a wingspan of around 2mm.

When they are at rest these wings are folded flat, one over the other, on their backs

A swarm of them can inflict about 3,000 bites in an hour

In that same timespan, 40,000 midges can land on an unprotected arm.

In prime breeding grounds larvae can reach a density of 24 million per hectare (10,000 square metres).

Midges are an international blight: a swarm near Mývatn lake in northern Iceland.

An estimated 20 per cent of working forestry days in Scotland are lost because of clouds of biting midges.

It is estimated that midges cost the Scottish tourist industry up to £268 million a year in lost visits.

in 1872 Queen Victoria fled a highland picnic after being “half-devoured” by midges.

On Rum, a local legend has it that - as punishment for improperly burying a body - a gravedigger was stipped, tied to a post and left outside for the midges to feast on. They killed him. Eventually.

There is an island called Midge Hill (492m) in South Lanarkshire… although it consequently sits far from the north-west highlands homeland of the true highland midge.

Dare you visit the summit of Midge Hill?

They lay their eggs in wet soil, bogs, mires and in the spongy surrounding ground.

It is only the female midge that bites.

The females are born with enough fat reserves to produce their first batch of eggs, but need a meal of mammal blood to grow any more.

… less than 10 per cent ever get one.

The males feed on plant nectar.

Once they’re found a blood source, midges emit pheromones and summon others nearby - hence the swarming.

Low light spurs their feeding habits - so they’re most active at dawn and dusk.

Their activity is reduced below 10 deg C and may actually stop below 3 deg C.

They first emerge in May and June, depending on the seasonal warmth and moisture levels.

A second batch tends to appear in late July and August.

A third batch can occur in September if the season is a warm one.

Mild and wet winters make for a bumper summer of midges.

Contrarily, a dry spring can make for a relatively midge-free summer.

But… even exceptionally cold winters are no protection: as they also reduce the numbers of the midge’s natural predators - bats and birds.

A rough rule is that the highland midge is only prevalent in areas that receive over 1250mm of rain each year.

Mildly acidic habitats (peaty soils, rushes, bracken, tree bark moss) are ideal locations for egg laying.

Two moist and overcast highland scenes in summer: midge territory.

The majority of the blood they feed on comes from cattle, sheep and deer.

They’re attracted to CO2 emitted in the breath of suitable mammals (e.g. humans).

Some people are more attractive than others, due to a mixture of specific body odour and temperature.

They’re more attracted to dark coloured clothing than to light.

They tend to bite in close proximity to their breeding sites.

... although they can be found up to 1km away.

They fly near to the ground, and are less active with wind speeds of over 6mph, or humidity below 60-75 per cent.

They have short, sharp mandibles which they use to pierce mammal skin.

They increase the blood flow of the victim via histamines in their saliva. This is also what causes the wound to swell afterwards.

It takes a midge five minutes of feeding to become engorged.

Traditional repellents have included pomegranate skins, mugwort, dill, fennel, lavender, citronella, thyme and smoke from a campfire.

Colloquial advice suggests that vitamin B1 supplements, Marmite, yeast tablets, Avon’s Skin-so-Soft oil may also help keep midges away.

A static and re-fillable midge trap which emits large amounts of CO2 to attract thousands (if not millions) of the insects will set you back over £600.

Search online and you can find some very sensible advice on how to avoid the highland midge. However, in some cases it almost seems that the cure is worse than the disease. Take the following advice from Scottish National Heritage, for example:

Avoid going outdoors on still summer evenings.

Still days and dull days are liable to be bad.

Shady or sheltered areas will have more active midges than dry open country.

Midges become less common above 700m.

Tents are not midge proof and treating the netting with an insecticide will help to reduce numbers getting in.

… which is perfectly sensible and important to bear in mind. But for most of us, staying inside on still summer evenings will prove an impossible ask. In that situation, the best solution comes via dousing yourself in insect repellents, covering your legs and arms with long-sleeved clothing and then protecting your head and neck with a well-made head net…

Powerful stuff… and so portable!

Sure, he looks great, but this kind of headgear just doesn’t cut it against the highland midge

This is slightly more like it.

If those options seemed a little old-school, you can find some more modern and effective alternatives here...

Lifesystems Insect Repellents and Mosquito Nets

It may make you look like the Dark Lord Sauron, but this kind of headgear is guaranteed to keep the midges from your eyes, nose, ears, mouth...

… and if you’d like to learn even more about the highland midge (and who wouldn’t?), I’d highly recommend a read of George Hendry’s witty and informative Midges in Scotland.

Make sure to visit the Lifesystems Facebook page and Twitter feed to share your own tales of midge attack, and your own tips on how to cope with them in the highlands and wild lands.

And try not to let them get to you.


Dan Aspel is a journalist and Mountain Leader. You can find him at

Visit to find a host of kit and equipment for your next outdoor adventure.

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