Protect Yourself From Mosquitoes; Populations On Rise After Storms

Dale K. Pollet, Chaney, John A., Grodner, Mary L.

News Release Distributed 10/12/05

With hundreds of square miles of standing water in Louisiana, LSU AgCenter entomologists advise homeowners to protect themselves from being exposed to the unusually heavy populations of mosquitoes following hurricanes Katrina and Rita.

"The large populations of mosquitoes will enhance the spread of mosquito-borne illnesses in humans and possibly kill unprotected pets and livestock," said LSU AgCenter entomologist Dr. Dale Pollet. "People need to take steps to protect themselves and their animals from these pests."

As a result of the heavy rainfall and storm surges, many low-lying areas, ditches, bayous and streams were flooded.
The loss of electricity in many areas also affected water treatment plants – making some of that stagnant water ideal for mosquito breeding, as well. And, to further enhance the mosquito population, the heavy rainfall filled containers, tree holes and other objects near homes.

Experts say all those factors provided the water and the habitat necessary for mosquito larvae to develop into adults.

"Once they become adults, which takes about seven to 10 days, female mosquitoes begin to search for a warm-blooded animal, bird or person to bite, because such a ‘blood meal’ will make their eggs viable," Pollet explained. "Then the female mosquito lays her eggs, and the life cycle continues."

Louisiana provides a habitat for more than 60 species of mosquitoes. These species can be grouped into fresh marsh, salt marsh, floodwater, rice field, urban and tree-hole mosquitoes.

The floodwater and salt water mosquitoes lay eggs on moist soil near the water’s edge. Those eggs can remain where they’re laid for years – until a major weather event occurs and triggers them to hatch. Then there suddenly is a population explosion of the pesky insects.

LSU AgCenter experts say people need to protect themselves from mosquito bites and the diseases mosquitoes can spread every time they go outside – but particularly around dawn and dusk. And they caution some species of mosquitoes transmit diseases such as West Nile virus, Saint Louis Encephalitis and Eastern Equine Encephalitis to humans and animals.

"People should remain informed about the problems and take precautions," Pollet warned.

As for the mosquitoes that transmit diseases to people, LSU AgCenter pesticide safety specialist and mosquito expert Dr. Mary Grodner says two species that generally live near a home are among the culprits. Those are the southern house mosquito and Asian tiger mosquito, she said.

The Asian tiger mosquito is the primary nuisance mosquito in Louisiana, according to Grodner.

"It lays eggs at the edge of the water and breeds in backyard containers like bird baths, flower pot saucers, swimming pool covers, boat covers, old tires and other items that catch and hold water," she said, adding, "It’s a vector of many mosquito-borne illnesses and bites mostly animals and humans."

The southern house mosquito, sometimes called the "sewer mosquito," breeds in organically rich areas such as drainage ditches and septic ponds, Grodner said.

"Although the southern house mosquito prefers to bite birds, it will feed on people, too," Grodner said, adding, "They usually bite near dusk and dawn."

To reduce the mosquito populations near the home, people should drain standing water, empty trapped water from containers, mow grass and reduce yard debris, the experts say.

Grodner also said mosquito control districts in various areas of the state will be applying granular larvacides by air to the floodwaters to control the development of larvae into adult mosquitoes.

The experts say homeowners also can use biological control on large bodies of water that cannot be emptied. Bacterial applications can be made with granules, liquids or blocks called dunks to help manage the larval populations.

Regardless of the control measures, some mosquitoes will emerge and have the potential of carrying diseases, so the experts caution even those who aren’t near floodwaters still should take precautions.

LSU AgCenter experts offer these tips for controlling mosquitoes around your home and protecting yourself from mosquito bites:

–Use a mosquito repellent each time you go outside.

–Wear long-sleeved shirts and long pants, when possible, and avoid dark colors.

–Avoid outdoor activities from dusk to dawn – when mosquitoes are more active.

–Fight mosquitoes. Don’t allow water to stand – or treat standing water with approved insecticides to kill mosquito larvae.

–Repair window and door screens to keep mosquitoes out of your home.

–Use an insecticide to spray areas of thick vegetation in your landscape.

–Remove debris from your yard.

–Mow grass regularly and keep shrubbery trimmed.

–Use pesticides safely and effectively. Read and carefully follow label directions on any insecticides or mosquito repellents you use.

–Always choose a pesticide that is registered with the Environmental Protection Agency (EPA) for your intended use.

For more details on mosquito control and other issues, visit the LSU AgCenter’s Web site at


Dale Pollet at (225) 578-2180 or
Mary Grodner at (225) 578-2180 or
John Chaney at (318) 473-6589 or

10/13/2005 2:12:33 AM
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