Los Angeles has once again ranked as the U.S. city with the highest mosquito activity, according to Orkin’s 2026 Mosquito Cities report, which tracks residential mosquito treatments performed between March 2025 and March 2026.
Chicago and New York followed in second and third place, respectively, highlighting how mosquito populations have expanded well beyond the southern United States in recent years.
According to Orkin, Los Angeles has held the top spot since 2021 after Atlanta led the rankings for six consecutive years between 2015 and 2020. Experts say the shift reflects the growing impact of climate change and the spread of invasive mosquito species into new regions.
The report also identified Milwaukee as one of the fastest-rising cities, climbing 15 positions to No. 23, while Minneapolis moved up six spots to No. 13. Meanwhile, Miami and Greensboro, North Carolina, dropped five places compared with last year’s rankings.
Several cities entered the ranking for the first time, including Traverse City, Michigan; Greenville, North Carolina; and Springfield, Illinois. Sacramento, California, and Phoenix also returned to the list.
Health officials warn that mosquitoes pose a greater threat than their bites alone. According to the U.S. Centers for Disease Control and Prevention (CDC), mosquitoes can transmit diseases including West Nile virus, Zika, dengue and Eastern equine encephalitis. The CDC has also warned that locally acquired dengue cases have become more common in recent years in parts of the United States.
Globally, mosquitoes are responsible for spreading malaria, a disease linked to more than 600,000 deaths each year. Although malaria remains rare in the United States, health experts recommend taking preventive measures during peak mosquito season.
