On Ambergris Caye, the wind decides whether the sand flies bite.

Yes, though the bite you'll notice on Ambergris Caye and Caye Caulker is usually a sand fly. Belize was certified malaria-free in 2023, and recent dengue seasons centered on the mainland rather than the cayes. Sand flies, tiny biting midges, come out at dawn, at dusk and whenever the wind drops, and a steady sea breeze keeps them down.

Sand flies follow the wind

What Belizeans call sand flies are biting midges, the no-see-ums of the US, weak fliers that bite ankles and lower legs. On Ambergris they are rarely a problem in a steady wind and worst at dawn and dusk after a still spell. Unraked beaches, north of the bridge or at the far south end, tend to be worse than the raked town beachfront. The lagoon sides of both islands, with mangroves and little wind, are the likelier calm-weather hotspots. Reef and snorkel boats to Hol Chan and Shark Ray Alley tend to be breezy and largely bite-free.

Sand flies don't follow Belize's June-to-November dengue season. One long-time Ambergris resident says they are around in August but far less bad than in December, and calm spells bring them out in any month.

On still days, spend dawn and dusk on a raised deck or the breezy, raked beachfront, spray feet, ankles and calves before you walk onto the sand, and wear light long trousers to beach-level dinners. Our sand fly guide explains the insect. On Caye Caulker the common local tip is coconut oil, or baby oil. Neither is an EPA-registered repellent. If you like the oil, add it over a registered product rather than using it instead.

Dengue is endemic, and quieter on the cayes

Dengue is endemic in Belize, and the CDC places the country in its group with frequent or continuous risk. Recent seasons have centered on the mainland. Three quarters of Belize's 865 cases by July 2024 came from Orange Walk, Cayo and Toledo, Amandala reported, and Toledo and Stann Creek had more than half of the 2,266 counted by mid-December 2024. In late November 2025 the San Pedro Sun reported more than 600 confirmed cases nationwide, most in Orange Walk and Corozal. There are no 2026 figures for Belize, and in October 2026 the Pan American Health Organization reported dengue rising again across Central America.

The dengue mosquito, Aedes, bites by day in San Pedro and in the Caye Caulker village, with peaks after sunrise and in the late afternoon. Repellent goes on over sunscreen in the morning, again in the late afternoon and after every swim or snorkel. Our dengue & Zika routine has the full schedule. Chikungunya and Zika have been reported in Belize in recent years, less than in Guatemala, and the same habit covers them.

The World Health Organization certified Belize malaria-free in 2023, the CDC lists no malaria prevention medicine for it, and it does not recommend the yellow fever vaccine. Belize isn't on the CDC's global dengue notice. A side trip to Tikal changes the malaria question, because the CDC recommends prevention medicine for Guatemala's Petén department. If it's on the plan, see a travel clinic 4–6 weeks before departure.

Where you're going

Scores are for a December–April trip. The disease picture is the same on both islands; the bites change with the beach and the wind.

The Belize briefing covers Placencia, Cayo and the cruise port.

What travelers report

Paraphrased from TripAdvisor forum threads and linked so you can read them in full. Neither is dated, and on the cayes the wind on the day matters more than the year.

• Ambergris Caye / San Pedro · Late July to early August

  Replies to a summer traveler said sand flies are rarely a problem when the wind blows and are worst at dawn and dusk after still spells; a long-time resident said they are present in August but far less bad than in December. Posters said unraked beaches north of the bridge or far south are worse, and disagreed on whether oil, Skin So Soft or DEET works best. TripAdvisor ↗

• Caye Caulker

  In a thread on oil-based protection, a reply said coconut oil or baby oil both work against sand flies but coconut oil is the more common local recommendation, and that small bottles are sold in the island's grocery stores. TripAdvisor ↗

One rule outlasts the trip. Any fever during or after your trip means a doctor visit, and you tell them you were in Belize, and in Guatemala if you went on to Tikal. Dengue usually shows up within two weeks.

Traveler questions