Heavy rain and heat bring out billions of mosquitoes in US

Author: Alex Sundby / CBS
20 July 2020, Brandenburg, Frankfurt (Oder): A mosquito of the species Aedes vexans sucks blood on the arm of biologist Doreen Werner, who is standing in the alluvial forest of the city. Doreen Werner from the Leibniz Centre for Agricultural Landscape Research (ZALF) at the Institute of Land Use Systems AG Medical Entomology is currently conducting research into mosquitoes in the floodplain forests. Due to the slight flooding of the German-Polish border river Oder, large parts of the alluvial forest and the adjacent meadows have been flooded in recent weeks. The consequence is a high increase in the mosquito population in these areas. In a test conducted by the researcher, around 60 mosquitoes were counted after one minute on just one arm. Photo: Patrick Pleul/dpa-Zentralbild/ZB (Photo by Patrick Pleul/picture alliance via Getty Images)

Sizzling temperatures and devastating storms in parts of the U.S. created a breeding ground for billions of pesky mosquitoes this summer.

“When temperatures are in the 90s and we have standing water, we’re going to have … billions of mosquitoes breeding,” Michael Raupp, an entomologist and a professor emeritus at the University of Maryland, said on “CBSN AM” on Monday. “There’s going to be a lot of biting going on.”

The remnants of hurricanes Henri and Ida dumped billions of gallons of water across multiple states. Raupp said standing water was “the perfect spot for mosquitoes to breed.”

Besides emptying birdbaths and turning over filled wheelbarrows, Raupp had another suggestion to cut down on potential mosquito hotspots. People with areas around their homes that don’t drain well after storms can buy environmentally safe larvicides that dissolve in puddles, Raupp said.

As for personal protection, Raupp said repellents containing DEET are the “gold standard” but there are alternatives that have the active ingredient picaridin, which became available in the U.S. in 2005, according to the National Pesticide Information Center. Raupp said people can also use botanically based insecticides or buy clothes pretreated with permethrin, which he said is a “very good” insect and tick repellent.

While this summer’s storms benefitted so-called inland floodwater mosquitoes, or Aedes vexans, in the Southeast and along the East Coast, Raupp said they aren’t known for spreading West Nile Virus, which is the leading cause of mosquito-borne disease in the continental U.S., according to the Centers for Disease Control and Prevention.

The number of West Nile cases in the U.S. are low and concentrated in Western states, Raupp said. However, Culex mosquitoes, which do transmit the virus, aren’t limited to the Western U.S.

“In my backyard right now, I’ve got a lot of Culex mosquitoes that are biting me whenever I go out the backyard, so it’s not time to put our guard down,” Raupp said. “The mosquitoes are here.”

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