Know your enemy
Culicoides impunctatus. The Highland midge. Roughly 1.4mm long, weighing almost nothing, possessed of a wing beat so fast it produces a high-pitched whine that will follow you into your dreams. There are 37 species of biting midge in Scotland. Thirty-six of them are a minor nuisance. One — impunctatus — is responsible for approximately 90% of the misery, the abandoned campsites, the ruined sunsets, and the inexplicable decision to eat dinner at speed in a sealed car park somewhere outside Ullapool.
The midge is not a joke. The midge is Scotland's most effective border control. It has done more to limit Highland tourism than any amount of midweek rain. Understanding it is not optional if you're planning to stand still outdoors anywhere north of the Great Glen between May and September.
The facts, stated plainly
Only the female bites. She needs blood to develop her eggs. She can detect the carbon dioxide you exhale from 200 metres away. She operates in swarms that can reach 500,000 individuals per square metre — a figure that sounds made up until you walk into one near Kinlochewe on a still August evening and come out looking like you lost a disagreement with a bag of gravel.
Midges cannot fly in wind above 7mph. This is the single most useful piece of information in this entire post. A breeze — any breeze — and they ground themselves. This is why the NC500's most exposed headlands and beaches are often midge-free while the sheltered glens 400 metres away are hellish. If you're being eaten alive, walk toward the sea.
They are most active at dawn and dusk. They are worst in still, humid, overcast conditions — in other words, in the standard Highland summer weather. The joke is that this describes roughly 80% of July and August. It is not entirely a joke.
Where they're worst
The west coast and northwest are significantly worse than the east coast and north coast. The sheltered sea lochs — Loch Broom, Loch Torridon, Loch Broom again (it deserves two mentions) — are particularly bad. Wester Ross in August on a still evening can be genuinely alarming.
The north coast between Durness and Thurso is much more exposed and therefore much more bearable. The east coast south of Wick is civilised by comparison. If you're planning to wild camp and you're midge-averse, choose your spots accordingly.
High ground is better than low ground. Moving water is better than standing water — midges breed in boggy, wet ground, so riverside campsites near wetlands are asking for trouble. Campsites on exposed headlands with an onshore breeze are your friends.
What actually works
DEET — specifically concentrations of 50% or above. The military strength stuff. It works. It smells like you've been marinating in chemicals, and it will dissolve certain plastics if you're not careful, but it works. Apply it to exposed skin before you step outside, not after the swarm has already found you.
Smidge — a Scottish-made alternative that's less aggressive on skin and clothing and works almost as well for most people. Widely available in Highland outdoors shops and petrol stations. Many people prefer it for everyday use.
Avon Skin So Soft Original Dry Oil — yes, the hand lotion. The one your grandmother uses. The Highland midge inexplicably cannot stand it, a phenomenon that baffled scientists for years before they identified a compound in the formula as the repellent. It is now genuinely stocked in Highland outdoors shops alongside the serious DEET preparations, which says everything you need to know.
A midge head net — looks absurd, works completely. If you're planning to stand at a viewpoint for any length of time on a still evening, swallow your dignity and put it on. The midges do not care how you look. You will care, briefly, and then you'll be grateful.
Staying inside — the nuclear option, and not really what you came to the Highlands for.
Timing your trip around them
June is the sweet spot. Long evenings, full light until 10pm, midges present but manageable. The first generation hasn't fully hatched and the second generation doesn't peak until mid-July.
May is even better — some years almost midge-free in the first half of the month, though you trade this for colder nights and the occasional late frost at altitude.
July and August are peak midge season, peak tourist season, and peak misery for anyone who hasn't packed repellent. They're also peak beauty — the NC500 in high summer, when it isn't raining, is extraordinary. Pack DEET and accept the terms.
September sees numbers drop sharply after the first cold nights. By the end of the month they're largely gone. October is midge-free and the light on the hills is extraordinary if you catch a clear week.
The Scottish Met Office actually tracks this
The Midge Forecast — yes, this is a real thing — is available at smidgeup.com. It maps predicted midge activity across Scotland day by day, using weather data and the known behaviour patterns of impunctatus. It is worth checking before you decide where to pitch a tent or how long you're willing to stand at Suilven viewpoint without chemical assistance.
Check it the way you'd check the weather forecast. Then ignore it slightly and go anyway. That's what the Highlanders do.