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Fox News Weather Center

El Nino-Driven Rains Spur Second Mosquito Season in Southern US

While October typically marks the time of year when mosquito season dies down, heavy rounds of rain across the Southern United States have led to a second and unseasonable mosquito season.

Water and temperature play a major role on the amount of mosquitoes, Orkin's Entomologist and Technical Services Director Ron Harrison, Ph.D, said.

"If it's really dry but the temperature is warm and an area sees a big rainstorm, a second bloom or season can occur," Harrison said.

While this occurrence is not unusual, water from recent El Niño heavy rain events in places such as Texas and South Carolina has contributed to higher amounts of mosquitoes.

The heavy rains have provided ample areas of standing water, or ideal breeding grounds for mosquitoes. Temperatures remaining above 50 F in these areas also created ideal conditions, allowing mosquitoes to thrive past the typical season.

"Usually the heavy population [of mosquitoes] declines by the first of October," Harrison said. "Traditionally, October is a drier month and the temperatures decline, causing the mosquitoes to not go through their cycle as fast."

Harrison estimates that this second season of mosquitoes should die off by the mid- to late-November depending on when the first freeze occurs in areas across the Southern U.S.

As the mosquitoes continue to thrive until temperatures dip low enough and the first freeze occurs, Harrison said those living in these areas need to be diligent in making sure that the mosquitoes are not developing in the standing water.

El Niño may lead to exceptional storminess across the South this year, making for ideal conditions for new generations of mosquitoes in areas where temperatures do not dip below freezing throughout the winter.