Mosquitoes year-round problem

BATON ROUGE, La. — Fall may have arrived and brought cooler weather with it, but experts warn the threat of mosquito-borne diseases still exists in Louisiana.

LSU AgCenter medical entomologist Dr. Michael Perich says even though lower temperatures have arrived, mosquitoes are still out and still carrying the threat of spreading diseases.

Recent news reports have revealed reduced numbers of West Nile cases in the state, and some have indicated the threat of mosquito-borne diseases is over for this year. But that advice applies more to states which already have freezing temperatures regularly, according to Louisiana experts.

"Louisiana has a subtropical climate — the preferred climate for mosquitoes," Perich said, adding, "One-third of the species of mosquitoes found in Louisiana are the same as those found in Brazil."

The south Louisiana habitat mimics tropical zones, creating conditions that support mosquitoes year-round, Perich points out. Some species actually thrive when temperatures are in the 50s and 60s, which are not uncommon as the high temperatures for south Louisiana during the winter.

Among the problems here in winter, which Perich cited, is one mosquito that can tolerate lower temperatures — "Culiseta inornata," or the winter mosquito.

This mosquito is primarily a late fall through spring mosquito. Its larvae are found in a wide variety of habitats, such as seepages, rain pools, ditches, canals, duck club ponds and salt marshes. These larvae can even tolerate water with a salt content of up to 2.6 percent. Culiseta inornata mosquitoes prefer to bite large domestic animals, but they also can bite humans. And they are carriers for several potential diseases.

Another cool-weather mosquito is "Culex restuans." These mosquitoes breed in similar habitats to those of the Culiseta inornata — although the water used by the Culex restuans can vary from nearly clear to grossly polluted. Among the places it may lay eggs are temporary groundwater, the edge of grassy swampland, sphagnum bogs, roadside ditches, tire ruts, hoof prints, discarded buckets, tires, catch basins, sewage effluent and septic seepage.

Both of these species usually are active in Louisiana from October to April, Perich said.

Because of the continued threat, Perich said it is still important to avoid getting bitten by mosquitoes. To cut down the mosquito population and prevent mosquito bites, LSU AgCenter experts say to:

• Protect yourself by wearing a mosquito repellent each time you go outside.

• Wear long-sleeve 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, 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 additional information on protecting yourself from mosquito-borne diseases, contact an LSUAgCenter Extension agent in your parish or go to

A. Denise Coolman writes for the LSU AgCenter.

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