The mosquitoes you actually need to worry about

Three species account for nearly all the disease transmission in the United States: Aedes aegypti, Aedes albopictus, and Culex pipiens.

Aedes aegypti — the yellow fever mosquito — is the most dangerous. Small, with white lyre markings on its back, it bites during the day and breeds in containers around your house (flower pots, gutters, bird baths). It carries dengue, Zika, chikungunya, and yellow fever. In the US, dengue outbreaks happen mostly in Florida, Texas, and Hawaii. Zika made headlines a few years ago but is now rare here.

Aedes albopictus — the Asian tiger mosquito — is almost as widespread but less efficient at spreading disease. Same viruses, but it’s more aggressive and adapted to cooler climates, so it ranges further north. It’s the one that’s been slowly colonizing the whole eastern half of the country.

Culex pipiens — the northern house mosquito — is your typical evening biter. It breeds in stagnant, nutrient-rich water like storm drains and septic tanks. This is the primary carrier of West Nile virus in the US, which is now endemic and causes a few hundred serious cases each year. It can also transmit St. Louis encephalitis and, rarely, filariasis.

Honorable mention: Anopheles species (malaria mosquitoes) still exist in the US, but malaria was eliminated here decades ago. You’d need an infected traveler or a local transmission cluster, which happens maybe once a year in some southern state, then gets stamped out quickly. Not worth losing sleep over.

Bottom line: if you live in the continental US, worry most about Culex for West Nile (every