The Places With the Worst Mosquitoes This Year

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For most of us, mosquitoes are just an annoyance — the little black things buzzing around us on our morning walk, the high-pitched whine in our ear when we’re trying to get to sleep. In reality, though, they’re a lot worse than merely annoying. 

There are over 3,500 species of these “little flies” (which is what “mosquito” literally means in Spanish) of the family Culicidae, and some species are among the deadliest creatures on Earth, spreading such diseases as malaria, dengue fever, chikungunya fever, eastern equine encephalitis, Rift Valley fever, West Nile, and Zika — some of which can sometimes be fatal. Some 725,000 people worldwide die of mosquito-borne illnesses every year. In comparison, deadly snakes are practically benign, claiming only about 138,000 lives. (But see these 10 surprising benefits of mosquitoes.)

Mosquitoes are a particular problem in sub-Saharan Africa, where 90% of the world’s malaria deaths occur, and in South America (especially Brazil) and Southeast Asia. The good news for the United States is that there are only about 200 types of mosquito in the country and its territories, of which only about a dozen can infect people. The rest are considered nuisance mosquitoes. 

The problem is, of course, that unless you’re an eagle-eyed entomologist, you won’t know which mosquitoes are which when one bites you. What’s more, with climate change, mosquitos are a growing nuisance. (Mosquitoes aren’t the only insects to watch out for. Here are some other dangerous bug bites to watch out for in summer.)

Even the nuisance mosquitos, though, are…well, a nuisance, leaving you with itchy bumps. It’s best to avoid the little flies entirely if possible, and that’s easier in some parts of the country than others.

To determine the worst counties for mosquitoes, 24/7 Tempo reviewed the report “2023’s Most Vulnerable Counties for Mosquito-Borne Diseases” by Pest Gnome, a site connecting users with pest-control experts. Drawing on sources including the Centers for Disease Control and Prevention and others, the site rated 800 U.S. counties on 12 metrics in four categories: mosquito prevalence, disease prevalence, mosquito-friendly climate, and mosquito control. To see Pet Gnome’s full methodology click here. We listed the 40 most vulnerable counties — those with the highest overall scores (out of 100).

Click here to see the worst counties for mosquitoes in 2023.

With the exception of two counties in New England, one in the Midwest, and one in the West, all of the 40 most vulnerable counties are in the South. Texas has the most, with 15, followed closely by Florida, with 12.