On St. John, the trails bring mosquitoes and the shade brings midges.

Are there mosquitoes on St. John? Yes, mostly on the shaded trails of Virgin Islands National Park, while no-see-ums, tiny biting midges, work the beach shade and the campground in the late afternoon. The island's 2024 dengue outbreak is over, the US Virgin Islands reported no dengue to the CDC in 2026 through late October, and no passport, malaria medicine or yellow fever vaccine is needed.

Dengue: a sharp 2024 wave, then quiet

The CDC counts the US Virgin Islands among the places with frequent or continuous dengue risk, and the territory's 2024–25 outbreak began on St. Thomas and St. John. The Virgin Islands Department of Health declared a dengue outbreak in the St. Thomas–St. John district in 2024. A CDC report published in October 2026 counts 40 confirmed cases on St. John between January 2024 and June 2025, most of them typed as DENV-2. Symptoms began for 38 of them between April and September 2024, and for none in 2025. Three patients were hospitalized.

The territory reported 47 cases in 2025, the early ones all on St. Croix, and CDC's notifiable-disease data, updated October 28, 2026, list no dengue cases reported by the USVI in 2026 through the week ending October 24. Those data also list one chikungunya case reported from the territory this year, without saying whether it was caught there, and no Zika. There is no malaria, and for yellow fever the CDC says "Vaccine is not recommended." Our US Virgin Islands briefing covers the territory-wide numbers, and the St. Thomas briefing covers Charlotte Amalie and the cruise piers.

Trails, shade and Cinnamon Bay

Mosquitoes are the trail problem. One forum poster found them worse than the midges on the paths around the Annaberg and Cinnamon Bay ruins, and the shaded park trails and the edges of mangroves and salt ponds are the still-air spots where they tend to gather. Some people get bitten far more than their companions. Treat a long-sleeved shirt, light trousers and socks with permethrin at home 48 hours before you fly, and put repellent on exposed skin at the trailhead and again after the swim at the end.

No-see-ums work the beaches and the campground. They tend to stay in the shade, don't follow people into the sun and bite most in the late afternoon, so spend that part of the day in the sun or the breeze and cover your ankles from about 4 pm. Campers at Cinnamon Bay are outdoors through dawn and dusk, so keep screens closed from dusk, wear treated long clothing at those hours and keep sand out of the bedding. The Maho Bay campground described in older forum threads has closed, and Maho Bay is now a beach. Villa renters should empty standing water around the house, where the dengue mosquito breeds. Our Barbados sand fly guide explains how the midges behave.

Where you're going

Scores are for a December–April trip.

What travelers report

Paraphrased from TripAdvisor and Fodor's threads and linked so you can read them in full. Only one is dated, a 2016 camping trip, and one describes the Maho Bay camp, which has since closed.

• Cinnamon Bay campground, St. John · February · 2016

  Replies to someone planning a February 2016 camping trip were mixed: one said bugs are manageable and mostly a problem after heavy rain, another reported many bites even through clothing. Advice was to stay off the beach at dawn and dusk, keep sand out of living spaces, use DEET and cover up, and one expert said the breezier winter months help. TripAdvisor ↗

• St. John · February to early April

  A forum poster said February, March and early April are the driest and most mosquito-free months on St. John. TripAdvisor ↗

• St. John camping (Maho Bay) · late afternoon

  In a thread on camping and no-see-ums, one poster said the midges stayed in the shade, did not follow people into the sun and bit most in the late afternoon, and recommended high-strength DEET sprayed on clothing and hats. A Maho Bay camper called the no-see-ums atrocious, and another poster said finer mesh screening keeps them out. Fodor's ↗

• St. John trails (Annaberg and Cinnamon Bay ruins)

  Asked how bad St. John's mosquitoes are, one poster said mosquitoes were the bigger problem, especially on the paths at the Annaberg and Cinnamon Bay ruins, while no-see-ums were only a nuisance. Others said bites vary a lot from person to person, and one advised getting off the beaches by 4 pm. Fodor's ↗

Two habits outlast the trip. Keep using repellent for three weeks after you get home. And any fever means a doctor visit, and you tell them you were in the US Virgin Islands. A trip that needed no passport is easy to leave out, and that one sentence points the doctor toward a dengue test.

Traveler questions