Mývatn's midge clouds mostly don't bite. The black flies from the Laxá do.
- No CDC travel notice for mosquito-borne disease
On calm June and July days the lake's midges rise in clouds thick enough to make a head net close to essential, and most sources describe them as non-biting. The biter is a black fly that breeds in the Laxá river. There are no mosquitoes or insect-borne diseases at the lake.
Yes, in huge numbers on calm days in June and July, though most sources describe the swarming midges as non-biting. They rise off the lake in clouds that fly into eyes, ears and mouths, and the bites come from black flies that breed in the Laxá river. There are no mosquitoes or insect-borne diseases at the lake, and our Iceland briefing covers the rest of the country.
Two insects, and only one bites
The swarms are chironomid midges, chiefly Tanytarsus gracilentus, which makes up two-thirds of the lake's secondary production. Its numbers swing by almost six orders of magnitude in irregular cycles of 4 to 7 years, a 2008 study in Nature found, so one summer can bring dense clouds and another very few. Most sources describe these midges as non-biting. Iceland has no Culicoides biting midges, the kind that bite horses elsewhere, a 2018 veterinary study notes, so Mývatn's swarms are a different insect from the midges that bite on Skye and across the Scottish Highlands.
The biter is a black fly, Simulium vittatum. A 1972 Icelandic agricultural research paper found it breeds in running water such as the Laxá, the river that drains the lake, rather than in the lake itself, and feeds on the blood of people and animals. Like black flies elsewhere, it bites by day near running water, and it tends to be worst on calm, warm days in June and July. It isn't known to spread disease in Iceland.
Where the clouds are thickest
Over land, the midges settle close to the water. Traps set in 2008–2011 showed 70% of them landing within about 330 feet (100 m) of the shore, with the heaviest fall 65 to 80 feet (20–25 m) inland, according to a 2015 paper in Ecology. That puts the lakeshore paths, the Skútustaðir pseudocrater walk and lakeside rooms in the thick of it, while spots a few hundred yards inland are likely lighter. Wind grounds both insects, so save lakeside walks for breezy spells.
A fine-mesh head net is the fix for the swarms. Local service stations sell them, and it pays to have one in the car before you reach the lake. Repellent has a reputation for doing little against clouds that thick. Picaridin 20% or DEET 20–30% on exposed skin and long sleeves still handle the black flies, and our picaridin vs. DEET comparison explains the choice.
June, July and the easy months
The swarms build in early summer and peak with the black flies in June and July. Midges are far fewer by August, the last flies hang on into early September, and by late September it is too cold for them. How bad a given June is depends on where the midge cycle stands that year and on the wind. August and September are the easy months.
Mosquitoes aren't part of the picture. Iceland had none on record in the wild until October 2025, when three Culiseta annulata were found on a farm in Kjós, north of Reykjavík in the southwest, far from Mývatn, and no follow-up has shown whether a population took hold. CDC's Iceland page lists no insect-borne diseases, recommends no malaria medicine and does not recommend or require the yellow fever vaccine.
Where you're going
How the main stops around the lake compare for a June–September trip.
Reykjahlíð
The main village on the northeast shore, with most of the hotels. Swarms reach the waterfront, so a room set back from the lake should fare better. Local service stations sell head nets.
Skútustaðir pseudocraters
A lakeshore crater walk on the south shore, inside the zone where most midges settle. Calm June and July days can mean clouds of them, so wear a head net and save the walk for a breeze.
Dimmuborgir & Hverfjall
Lava formations and a tephra crater east of the lake, farther from the shore. Swarms likely thin with distance from the water, though a calm day can still bring midges.
Mývatn Nature Baths & Námaskarð
Geothermal baths and the Hverir steam field on dry, barren ground east of the lake. Likely lighter than the shore, though it's worth keeping the head net in the car.
The Mývatn kit
- A fine-mesh head net: the one item that works against the swarms. Pack one from home or buy one at a local service station.
- Picaridin 20% travel sprays for the black flies by the Laxá. The 3.4 oz size rides in a carry-on.
- A light long-sleeved layer, which Icelandic summer weather calls for anyway.
What travelers report
Paraphrased from two TripAdvisor threads and linked so you can read them in full. Neither is dated, and the lake changes from one calm or breezy day to the next.
- Iceland (Mývatn, south) · late August
In an older, closed thread, a traveler asked about black flies in the south in late August. Replies said midges are the main nuisance, around Mývatn and near horses, most common in early and mid summer and much fewer by August; that they can bite but are not dangerous; that a cheap head net from a service station is the best defense; and that Iceland has no mosquitoes. TripAdvisor ↗
- Lake Mývatn · late September
Asked whether the midge problem is over by late September, replies said the midges are a summer thing, that the last flies are around at the beginning of September but not later, and that by September and October it is already too cold for them. TripAdvisor ↗
As on any trip, a fever during or after it means a doctor visit, and you tell them where you were.
Traveler questions
Do the Mývatn midges bite?
Most sources describe the swarming midges as non-biting. They are chironomids, and Iceland has no Culicoides biting midges, the kind that bite in Scotland. They fly into eyes, ears and mouths, which is miserable enough. The biter at the lake is a black fly that breeds in the Laxá river. A fine-mesh head net handles the swarm, and picaridin or DEET on exposed skin plus long sleeves handle the black flies.
When can I visit Mývatn without the midges?
August and September are the easy months. The swarms and black flies peak in June and July, thin out by August and are gone by late September, when it is too cold for them. On any summer day a steady wind helps, and some years bring far fewer midges than others.
Are there mosquitoes at Lake Mývatn?
No. Iceland had none on record in the wild until October 2025, when three Culiseta annulata were found on a farm in Kjós, north of Reykjavík, far from Mývatn. No follow-up has shown whether a population took hold, and the species is not linked to dengue or chikungunya. CDC lists no insect-borne diseases for Iceland.
Where should I stay at Mývatn to avoid the swarms?
Reykjahlíð, on the northeast shore, has most of the hotels. Pick a room set back from the water if you can, since a 2015 study found that 70% of the midges that come ashore land within about 330 feet (100 m) of the lake.
Sources
Health authorities, surveillance reports and news coverage of official bulletins used for this briefing, last checked October 2026. Traveler reports are linked where they appear. This page summarizes public-health guidance and is not medical advice.