Mosquitoes are a constant presence in Costa Rica due to its tropical climate, but their "badness" depends entirely on where you are and the time of year. In the lush, humid rainforests of Tortuguero or Corcovado, and during the "green season" (May–Nov), mosquitoes can be quite bothersome, especially at dusk and dawn. However, in the breezy, drier Guanacaste region, they are much less of an issue. While the nuisance factor is real, the health risk in 2026 remains relatively low, though mosquito-borne illnesses like Dengue and Zika do occasionally occur in coastal lowlands. The best defense is a "peer-to-peer" strategy: wear light-colored, long-sleeved clothing and apply a repellent containing DEET or Picaridin. Most high-end eco-lodges provide mosquito netting over beds, though with modern screened-in windows, it is often more for "aesthetic" jungle vibes. If you stay in air-conditioned hotels or at higher elevations like Monteverde, you will likely see very few mosquitoes.