On Vieques and Culebra, the beaches bite at sunset.

Are there mosquitoes on Vieques and Culebra? Yes, though the bites visitors complain about most come from no-see-ums, tiny biting midges that work the beaches in calm air around dawn and dusk. Dengue is endemic across Puerto Rico and its mosquito bites by day, but the island's 2026 count is far below the last two epidemic years.

Dengue: a calmer year, no island figures

Puerto Rico declared a public-health emergency for dengue in March 2024. A CDC report counted 6,291 cases that year, and the Health Department later extended the epidemic declaration through December 2025, a year that brought another 3,389 cases, according to department figures reported in the local press.

2026 has been much quieter. The Health Department's weekly report dated September 23 counted 922 cases with symptoms starting between January 1 and September 16, and weekly cases were below the epidemic threshold in mid-September. About half of those patients were hospitalized, and 4 died. The department doesn't publish separate figures for Vieques or Culebra, so plan on the island-wide picture, with dengue all year and less of it in winter.

The CDC counts Puerto Rico among the places with frequent or continuous dengue risk, but it has no travel notice for mosquito-borne disease here. There is no malaria or yellow fever on either island, and the CDC has reported no locally acquired Oropouche in US states or territories. Put repellent on over sunscreen in the morning and again in the late afternoon, and sleep in a screened or air-conditioned room. Our dengue & Zika daily routine has the full schedule.

Sunset midges and the bio bay

On Vieques, Green Beach at Punta Arenas, on the far west end, draws the most no-see-um complaints. Posters blame the nearby Kiani Lagoon and say the bugs thicken through the afternoon and peak at sunset, when the breeze drops. Posters also mention bugs at Mosquito Pier after dusk, while breezy beaches and rentals tend to see fewer bites. These are biting midges, weak fliers that a breeze grounds. Go to the west end in the morning and leave by early afternoon.

On Culebra, the bites blamed on "sand fleas" at Flamenco Beach are biting midges, called mimis locally. They bite in the calm early morning and late afternoon, and the welts show up hours later. Spray or cover ankles at those times and skip the piles of washed-up seaweed. Culebra tends to have mosquitoes all year, more in the rainy season, and campers at Flamenco are outdoors through dusk and night, so a screened tent is worth bringing.

Mosquito Bay, Vieques's bioluminescent bay, is seen only at night, by kayak or electric boat from Esperanza. Calm water beside mangroves after dark is a likely time and place for mosquitoes and midges. Wear light long sleeves and long pants, treated with permethrin at home if you can, and put repellent on hands, neck and ankles before boarding. Our Barbados sand fly guide explains how the midges behave.

Where you're going

Scores are for a December–April trip.

Our Puerto Rico briefing covers San Juan, El Yunque and Rincón. Continuing east to St. Thomas or St. Croix? See the US Virgin Islands briefing.

What travelers report

Paraphrased from TripAdvisor threads and reviews and linked so you can read them in full. None is dated and most are older, and midge bites swing a lot with the wind on the day.

• Green Beach, Vieques · sunset

  A reviewer called Green Beach the best place to watch the sunset but found the bugs bad around dusk and suggested watching it from inside the jeep. TripAdvisor ↗

• Vieques

  Posters described the biters as almost invisible flying no-see-ums, distinct from the sand fleas that live in the sand, and most likely a kind of biting midge. TripAdvisor ↗

• Culebra · year-round, more in the rainy season

  A Culebra thread said mosquitoes are around all year, with more in the rainy season, and that the mosquitoes that spread dengue are out during the day. TripAdvisor ↗

• Culebra (I Ventures tour)

  A reviewer of a Culebra tour called the beach amazing but warned about biting sand flies. TripAdvisor ↗

One rule outlasts the trip. If you get a fever within two weeks of coming home, see a doctor and say you were in Puerto Rico, on Vieques or Culebra. A domestic flight is easy to leave out of the conversation, and that one sentence points the doctor toward a dengue test.

Traveler questions