Glasgow Midge Risk Forecast

When is midge season in Scotland?

Scotland’s biting midge — Culicoides impunctatus, a two-millimetre fly of which only the female bites — is active from roughly late May to mid-September. There are usually two waves: a first generation from late May into June, and a second, often larger one that peaks from late July into August. July and August are the worst months. From October to April they are dormant, which is one good reason to walk in Scotland in winter. Midges do not carry disease; the bites are simply an itchy nuisance.

The one variable that matters most: wind

A Highland midge is a weak flier. Once the wind reaches roughly 7 mph (11 km/h) it cannot make headway and simply stops flying; below about 4 mph it moves freely. There is no gradual decline — there is a threshold, and past it the midges are gone. This single factor outperforms every repellent on the market, which is why an exposed, breezy spot can be midge-free while a sheltered glen fifty metres away is swarming. If you can feel a breeze on your face, you are probably fine.

Temperature and time of day

Midges need mild conditions — above roughly 10°C — to fly, and they are most active at dawn and dusk (about 5–9 am and 6–10 pm in summer). Bright midday sun, a hot afternoon and cool temperatures all keep them down. Warm, still, overcast and humid is the combination to avoid.

What actually works

• Wind and exposure — free, and the most effective thing there is. Choose open, breezy ground over a sheltered glen on a still evening.
• DEET at 20–50% — the most heavily tested repellent. Effective, but it damages plastics, so keep it off watch straps, sunglasses, phone cases and tent seams.
• Picaridin (also called icaridin or Saltidin), 20% — the other repellent with strong field evidence, and the one most Scottish walkers carry. It is odourless and plastic-safe; the widely stocked brand is Smidge.
• A fine-mesh head net — essential if you are going to be still for any length of time at dusk in peak season.

What is not worth relying on: citronella, ultrasonic devices and wristbands, which perform poorly in real field conditions. Moisturisers such as Avon Skin So Soft are a Scottish folk remedy — sometimes they seem to help, sometimes not, and they are no substitute for DEET or picaridin at peak density.

Where they are worst around Glasgow

Sheltered, damp and wooded places are the problem: the gorge paths at Linn Park, the woodland and loch-side at Rouken Glen and Mugdock, and any riverbank or loch edge on a still evening. Exposed high ground such as Cathkin Braes or the top of the Necropolis, and breezy riverside walks, are usually far better. Wind and height both reduce them — the midge is very much a creature of the calm, sheltered glen.