The heavy rains that Tropical Storm Lee dumped on parts of Louisiana created more than just a few soggy days — it also gave mosquito eggs the water they needed to hatch.
From East Baton Rouge Parish to Calcasieu Parish, mosquito populations have exploded in the past few weeks.
“Tropical Storm Lee dumped a lot of water in the area and flooded eggs that had been waiting for water,” said Matthew Yates, director of Mosquito and Rodent Control in East Baton Rouge Parish.
With the additional rain, local rivers also flooded areas where mosquito eggs had been left, adding to the increase.
Mosquitoes in forested areas normally stay in those areas except when there are large numbers that hatch at the same time — then some leave in search of a meal, he explained.
And some of these mosquitoes could be traveling quite a distance.
The northern floodwater mosquito and the headhunter mosquito are the two mosquitoes currently found in the parish, Yates said.
The northern floodwater mosquito can travel 50 to 100 miles without a problem, and another mosquito — the light salt marsh mosquito — also can travel long distances, he said.
In addition to the migrations, the mosquitoes are also hatching in installments, so keeping them under control can be a challenge.
“We can go in an area, spray it and do a good job, and then have a whole new infestation the next day,” Yates said.
In East Baton Rouge Parish, controlling the problem involves two spray flights a night, increased truck spraying at night and extra work by day crews looking for trouble spots, he said.
However, even with the additional mosquitoes, it’s not likely that there will be an increase in mosquito-borne viruses, including the West Nile Virus, Yates said.
One reason is the mosquitoes being found now are not good at transmitting those kinds of diseases, Yates said.
The increase in mosquitoes is seen all over the area where Tropical Storm Lee brought rain.
“We’ve got mosquitoes,” said Jeanine Tessmer, director of the mosquito abatement district for Livingston Parish. “Our phones have been going crazy with calls.”
Tessmer said she’s increased the number of trucks that are spraying in the parish from five to seven to help reduce the amount of time it takes to spray the whole parish.
However, a limited budget — because of the way the program is funded by a set fee — means she can’t do aerial spraying.
In July, the parish sprayed two areas because tests showed that those two areas had a growing number of virus-carrying mosquitoes, she said.
However, with a budget of around $900,000 for the year, it would probably cost $800,000 to spray the entire parish because the program doesn’t own its own planes and needs to contract for that work.
In Ascension Parish, Mosquito Control Department Manager David Matassa said the department is fighting the largest outbreak of mosquitoes it’s seen this year.
“Inspectors taking landing rates of mosquitoes are picking up as many as 75 to 100 mosquitoes per minute in many locations in Ascension Parish.
Crews have doubled their efforts in treating most areas of the parish using their fleet of trucks, and will continue to do so until mosquito populations are reduced to normal levels,” Matassa wrote in a press release.
The boom in mosquito population occurred across much of south Louisiana from Calcasieu to St. Tammany parishes, said Herff Jones, president of the Louisiana Mosquito Control Association and executive director for the Iberia Parish Mosquito Abatement Program.
“Even north to Alexandria, we’re getting reports from some of those parishes as well,” he said about increases in mosquito populations in Tropical Storm Lee’s wake. “What a rain event like Tropical Storm Lee does for us is it will flood areas that aren’t normally inundated by rain.”
In addition, the fluctuation in high and low tides in coastal parishes is a lot greater during low pressure systems, including tropical storms, he said.
That brings water into areas where the eggs may be laid, and they just need water to hatch, he said.
“These eggs can last from one season to the next,” he said.
Scott Willis, director of the Calcasieu Parish Mosquito Control, said employees at his office saw a spike in mosquito populations during the week of Sept. 12 — when the office received 275 calls about mosquitoes compared with about 200 calls last year.