Climate change leads to more intense hurricanes — and more mosquitoes

Southwest Louisiana suffering after back-to-back hurricanes followed by mosquito swarms

By: - October 20, 2020 12:08 pm

Salt water mosquito larvae in a sample cup taken from Cameron Parish. (Photo courtesy of Josh Hightower, the director of Cameron Parish Mosquito Control.)

Mosquitoes are a part of life in South Louisiana. But this year’s active hurricane season has made the biting insects intolerable — even to Cajuns.

Parish mosquito-abatement offices around the state perform a simple test to see whether mosquitoes are bad enough to spray pesticides: They have a person stand still for one minute and count the number of mosquitoes that land on them. In Cameron Parish a week after Hurricane Laura, the mosquito-abatement office counted 200 mosquitoes landing during those 60 seconds, said Josh Hightower, the director of Cameron Parish Mosquito Control.

“In our parish, having bad mosquitos is pretty normal,” Hightower said.  “But right after Laura they were really high.”

That’s why U.S. Air Force C-130 aircraft will start spraying for mosquitoes at dusk today over Acadia, Calcasieu, Cameron, Iberia, Jefferson Davis, Lafayette and Vermilion parishes, according to the Governor’s Office of Homeland Security and Emergency Preparedness, or GOHSEP. 

Spraying will continue for about six days, depending on weather. GOHSEP and the Louisiana Department of Health requested additional mosquito control from the Federal Emergency Management Agency Wednesday Oct. 14 when it became clear that, after back-to-back hurricanes, local efforts could not control mosquitoes in the region.

Mosquitoes can leave behind more than just an itchy welt. The insects transmit a number of diseases — including malaria, dengue and West Nile — making them the world’s deadliest animal. Climate change is expected to further spread mosquito-borne diseases and make them more prevalent in some areas. Warmer temperatures are projected to expand the ranges of disease carrying mosquitoes north and south to places where they weren’t previously present, said Dr. Dawn Wesson with Tulane’s School of Public Health and Tropical Medicine.

Hurricanes typically bring rainfall that results in flooding. Flood waters cause eggs previously laid in the soil by mosquitoes to hatch. The bugs mature to biting age in about a week. This can create swarms of mosquitoes, as were seen in parts of the state after hurricanes Laura and Delta.

Since Hurricane Laura, eight parishes have sprayed pesticide over two million acres of land to control mosquitoes, according to the Louisiana Department of Health. The type of mosquitoes that hatch after a hurricane — called floodwater mosquitoes —  are not primarily the carrier of diseases. But the mosquitoes torment cattle already stressed from weathering a storm. In some areas, weakened cattle died from suffocation when they breathed the insects in through their nostrils.

The bugs can also be a nuisance to out-of-state workers who aren’t as used to the pest that’s jokingly referred to as Louisiana’s state bird. Cameron Parish lowered the threshold for spraying to accommodate crews cleaning up debris, restoring utilities and rebuilding roofs. “We’re trying to keep the mosquitoes down so that they can get work done,” Hightower said.

Pesticide used to control mosquitoes is sprayed from airplanes in the dark, when mosquitoes are most active and bees have returned to their hives. But many of the lights on cellphone towers in the area are still out. So, to avoid collisions with those towers, contractors with night vision goggles are doing the job, Hightower said. Since Sept. 1, the abatement office has applied pesticide to more than 986,000 acres in Cameron Parish. That’s more than double the amount of spraying the parish does in a typical year, Hightower said.

The Cameron Parish Mosquito Control building was damaged by Hurricane Laura. (Photo courtesy of Josh Hightower, the director of Cameron Parish Mosquito Control)

Mosquito control workers continue to monitor mosquitoes in the wake of Hurricane Delta, despite losing their office and houses to Hurricane Laura. “All my workers are either displaced or living off their property in campers,” Hightower said. “I’m the only one that’s actually living in their house.”

The Ouachita Parish Mosquito Abatement District in North Louisiana is also keeping a close eye on mosquito numbers following Hurricane Delta. While the parish has not had many floodwater mosquitoes, it’s had more mosquitoes test positive for West Nile this year than any other parish in the state.

The parish sends samples of mosquitoes off to a Louisiana State University lab once a week to be tested for the virus. The virus began showing up around late July in southern house mosquitoes, which are  commonly known to carry the illness, said Shannon Rider, the Director of Ouachita Parish District Mosquito Abatement. The district sprayed pesticide and applied larvicide to kill the southern house mosquitoes carrying the virus.

West Nile virus reached Louisiana in 2001. Most people infected with West Nile virus do not have symptoms. But in 2002, there were more than 200 serious cases in the state and 24 deaths. The number of cases since then has fluctuated widely every year, but spiked again in 2012 with higher-than-normal temperatures.

More than 20 parishes have found mosquitoes carrying West Nile this year, and nine people in the state have contracted the more serious form of the disease, which can cause disorientation, coma and paralysis. Last year, there were 11 serious cases of West Nile in Louisiana, according to data provided by the Louisiana Department of Health.

Rider said she’s not concerned that the virus will become prevalent in the floodwater mosquitoes from Hurricane Delta, which are now reaching biting age. Still, she said residents should take precautions to avoid getting bitten by mosquitoes, as they could be carrying a serious disease. “You don’t want people to be cavalier or casual with their own protection,” she said. “Just one could have it, and that one could be the one to bite.”

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Sara Sneath
Sara Sneath

Sara Sneath is an environmental journalist who lives in New Orleans with her dog and three bikes.