Will the Hard Freeze Diminish the Mosquito Population?

Posted by:  Michelle Davis

Many people believe that freezing temperatures will kill off the mosquito population.  However, this is not true.  Southern Louisiana has experienced periods of freezing and below freezing temperatures recently.  During these periods the mosquitoes seemed to have disappeared.  With a closer look at what is really happening, we see that a majority of the mosquitoes have been diminished with our below normal winter weather. But, there are a few breeds of mosquitoes that only are noticed in the winter months.

 According to the Delta Farm Press, 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.

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.

According to the News Star, mosquito eggs actually will not die in below freezing weather.  Despite dropping below freezing for the past several days, Ouachita Parish Mosquito Abatement District Interim Director Shannon Rider said area residents shouldn’t expect fewer mosquitoes during the spring and summer months.

“Unfortunately, it probably really won’t do anything to the mosquito population,” Rider said. “The most it will do is prolong the mosquito eggs hatching by making them inactive for a little longer.”

Rider said a common public misconception is that the cold weather would reduce the mosquito population by killing the mosquito eggs, which are generally laid by adult mosquitoes the previous year. Rider said freezing conditions don’t kill the eggs, which could remain dormant for two years.

During a mild winter, Rider said mosquito eggs generally begin hatching on a large scale in late April and early May. But she’s doubtful that the colder temperatures this month will delay the hatching of the eggs more than several weeks.

 “It probably won’t even affect them that much,” Rider said. “It’s just hard to speculate because there’s so many variables. They will just lay dormant until conditions are right.”

For more information on how to protect you and your family this upcoming spring, please give Michelle a call at 337-585-3800 or visit our website at http://lafayette.mosquitosquad.com/.

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