Prepare for increasing number of mosquitoes in Arizona

With the rain we’ve had recently, Arizona residents should prepare for increased mosquito activity in the days and weeks ahead.

The Arizona Department of Health Services reported 63 cases of West Nile virus so far in 2025 here in Arizona. Mosquitoes can carry deadly diseases, including Zika and West Nile virus.

ASU researchers said mosquitoes are also surviving our summer weather longer than they have in the past.

John Townsend, Vector Control Division Manager of Maricopa County, joined “Arizona Horizon” to explain how Arizonans should prepare for the increased number of mosquitoes in Arizona.

There are a variety of different species of mosquitoes that reside in Arizona. Townsend noted that there is daytime and nighttime biting mosquitoes that carry different levels of risk in their bites. The nighttime mosquitoes gain their notorious reputation due to the viruses they can potentially carry. These mosquitoes pick up these diseases from local birds in the area.

“We have nighttime biting mosquitoes that you should worry about,” Townsend said. “And then we have daytime biting mosquitoes that are really more of a nuisance.”

The mosquitoes that residents are likely most familiar with were brought to the state around 25 years ago according to Townsend. They leave bites around the hands, feet or ankles, and breed in outdoor areas and backyards.

“They’re really adapted to living around people,” Townsend said. ” Those are the ones that carry West Nile.”

Despite the large amounts of rain that hit the Valley during the fall, there is not going to be a large surge of mosquitoes. The rainy weather brought with it lower temperatures than average, effectively stopping the breeding of more mosquitoes.

“Once those temperatures at night get down to 50 degrees, the eggs that have been laid all over the place won’t be hatching out,” Townsend said.

To fight this issue, Maricopa County’s Vector Control Division sets out 850 surveillance traps every single week across the Valley. They also send all of their traps to labs to detect common viruses.