Milford Sound's sandflies are New Zealand's one real bug problem.
The CDC lists no mosquito-borne disease for New Zealand. The bites people remember come from sandflies, small biting flies notorious in Fiordland and with a reputation along the West Coast and at Abel Tasman. Here's where they are and the routine that keeps a South Island summer comfortable.
New Zealand has a few mosquitoes, and the CDC lists no mosquito-borne disease for the country. The insect visitors remember is the sandfly, or namu, a small biting fly notorious at Milford Sound and in Fiordland, with a reputation along the West Coast and at Abel Tasman. December to April is the South Island's busiest season and prime sandfly time, so pack repellent and long sleeves.
What a New Zealand sandfly is
The name causes confusion. New Zealand's sandflies are black flies of the genus Austrosimulium. Te Ara, the government's Encyclopedia of New Zealand, counts 13 species, of which only two bite people, and only the females bite. That makes them a different insect from the Caribbean "sandfly," a biting midge or no-see-um that bites ankles at dawn and dusk and is grounded by a breeze, which our Barbados sandfly guide covers. They're also unrelated to the phlebotomine sand flies that spread leishmaniasis in other parts of the world. Black flies bite by day near running water, which suits a country of rivers, lakes and fiords, and Te Ara notes they seldom bite in the dark.
They carry no disease in New Zealand. The bites can itch for days, though, and some people react strongly. Try not to scratch; forum posters recommend an anti-itch cream or an antihistamine for bad reactions.
Milford Sound and the other hotspots
Te Ara calls the West Coast and Fiordland infamous for sandflies, and the end of the Milford Track, where walkers wait for the boat, is named Sandfly Point. Milford Sound is the country's best-known sandfly spot, especially on the foreshore and for anyone staying overnight or camping. If that worries you, consider basing yourself in Te Anau, which has a reputation for being relatively sandfly-free, and doing Milford as a day trip. The West Coast around Franz Josef, Fox and Hokitika is the other classic sandfly region, and the Abel Tasman beaches and tracks have a similar reputation.
Sandflies tend to be worst on still days near water. Travelers say keeping on the move helps and that the flies stay on land rather than following the boats, so time on the water tends to be easier. Put repellent on before you arrive at Milford, covering every patch of exposed skin, ankles, hands and neck included. Wear long sleeves and long pants, tucked into socks on the tracks. Picaridin 20%, DEET 20–30%, oil of lemon eucalyptus or PMD 30%, and IR3535 are all EPA-registered options, and our repellent timing guide shows when to reapply on a long walking day.
Where you're going
Here is how the main stops compare for a December–April trip.
Milford Sound, Fiordland & Te Anau
The country's most notorious sandfly area, worst for overnight stays and camping on the Milford foreshore. Te Anau makes the calmer base.
West Coast & Abel Tasman
Franz Josef, Fox, Hokitika and the Abel Tasman coast have a reputation for sandflies on beaches, riverbanks and tracks. Put repellent and long sleeves on before every walk.
Queenstown
Few problems in town. Sandflies tend to show up on lakeside and backcountry walks, so keep repellent in the daypack.
Auckland
No mosquito-borne disease and, by most accounts, little biting-insect trouble. The repellent matters once you reach the South Island.
The New Zealand kit
- Picaridin 20% travel sprays: odorless, kind to skin you'll re-treat every day and small enough for a jacket pocket. Cover hands, neck and ankles as well as arms.
- A full-size backup in the checked bag for a two-week road trip or a family, so you're not rationing spray on the West Coast.
- Long sleeves, long pants, socks and an anti-itch cream or antihistamine. Fabric covers what repellent misses, and the cream helps with bites that itch for days.
What travelers report
Paraphrased from TripAdvisor forum threads and linked so you can read them in full. Neither thread is dated to a year, and sandfly numbers vary with wind, weather and where you stop.
- Milford Sound / Te Anau · January
A camper planning a January trip asked whether to camp at Milford Sound or Te Anau. One reply advised against an overnight stay at Milford because of sandflies and called Te Anau relatively sandfly-free; another said the flies are a nuisance but not hideous with decent repellent. The poster chose to camp at Te Anau. TripAdvisor ↗
- Milford Sound · year-round
Asked whether Milford Sound has a low season for sandflies, a poster answered that there is no low season. TripAdvisor ↗
The usual end-of-trip rule still applies. Any fever during or after your trip means a doctor visit, and you tell them where you traveled, especially if New Zealand was one stop on a longer trip through the tropics.
Traveler questions
Are there mosquitoes in New Zealand?
A few, and they tend to be a minor nuisance next to the sandflies. The CDC lists no mosquito-borne disease for New Zealand and no malaria. The World Health Organization lists New Zealand only for imported Zika cases picked up on travel elsewhere.
Should I stay overnight at Milford Sound?
If the bites worry you, base yourself in Te Anau, which has a reputation for being relatively sandfly-free, and visit Milford as a day trip. Overnight stays and camping on the Milford foreshore get the worst of it. If you do stay, keep repellent and long sleeves on from morning to evening, since sandflies tend to bite by day.
Is there a time of year without sandflies?
Not a reliable one. They tend to be worst in the warmer months, which line up with the December–April travel season, and Milford Sound has a reputation for biting in every season. Pack repellent whatever month you go.
Do I need any vaccines or medicines for New Zealand?
Not for insect-borne disease. There is no malaria, the CDC doesn't recommend the yellow fever vaccine for New Zealand, and the vaccine isn't required for entry.
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.