Yes, Costa Rica has a significant mosquito population, particularly in the lowland rainforests, coastal mangroves, and during the rainy season (May to November). Because of the country's incredible biodiversity and tropical climate, mosquitoes are a year-round presence, though they are much less common in the higher-altitude "Cloud Forests" like Monteverde or in the central valley cities like San José. In 2026, the primary concern for travelers remains nuisance bites and the risk of mosquito-borne illnesses such as Dengue, Zika, and Chikungunya. While the government maintains rigorous "fogging" programs in tourist areas, visitors are strongly advised to use repellents containing DEET or Picaridin and to wear long-sleeved "safari-style" clothing during the dawn and dusk hours when activity peaks. Most eco-lodges provide mosquito netting over beds as a standard precaution, ensuring that even in the heart of the jungle, you can sleep soundly without the constant "buzz" of these tiny but persistent residents.