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Mosquito population off the charts
Published September 30, 2009
ANGLETON — Mosquito counts are above the highest measurable range in much of the southeastern part of Brazoria County, and mosquito control officials are hitting the insects with all they have.
Fourteen trucks and two airplanes are spraying as often as weather permits to quell the third outbreak of the pesky insects this year, Mosquito Control Supervisor Jim Ryan said. The others were in April, then late May and early June.
Although rain over the area has exacerbated the problem by keeping planes from spraying, it hasn’t been the chief cause in the population increase, Ryan said. Rising tides have reached saltwater mosquito eggs laid in mud surrounding marshes, and when the eggs are submerged, they hatch.
“We were looking for them, then overnight they were thick,” Ryan said of the outbreak which began about a week ago. “All we can do is survey and be ready and respond as soon as outbreaks do happen.”
Numbers are taken when an employee stands in a particular area and counts the number of insects landing below their waist. Once the number reaches 100, the employee stops counting. Counts in the past week have netted 100 or more in areas “throughout the county,” Ryan said.
When the tide is normal, the bug population can feed on the blood of animals in the marsh, which includes much of the southeastern part of Brazoria County and the San Bernard River.
Once the new eggs hatch, there’s not enough food for the mosquitoes and they go in search of dinner. Jones Creek and Demi-John often are the towns hit first, followed quickly by Oyster Creek and Surfside, then Freeport, Clute, Lake Jackson and Brazoria.
During the current outbreak, salt marsh mosquitoes are more prevalent in the Angleton, Liverpool, Danbury and Alvin areas, and as far north as Manvel, Ryan said.
“We knew with the high tide a week ago and flooding of the salt marsh we were going to see mosquitoes,” he said. “It has ramped them up.”
Controlling the parasitic insects isn’t cheap, County Auditor Connie Garner said. The mosquito control district’s budget this year is $2.4 million, was $2.3 million last year and about $2 million three years ago. That number might seem high to some people — until they’re overrun with mosquitoes, said Arthur Velasquez, executive assistant to County Judge E.J. “Joe” King.
“We’re doing the right thing,” Velasquez said. “We want to keep the mosquitoes down.”
Mosquitoes can carry various diseases, including West Nile virus and encephalitis. So far this year, officials trapping mosquitoes in various locations throughout the county have found no infected bugs, Ryan said.
“We’ve been fortunate this summer,” he said. “We’ve found no pools of mosquitoes testing positive this year. That doesn’t mean they’re not out there. We just haven’t found any.”
There are about 2,500 known species of mosquitoes, and of those, about 240 are in the United States and 80 are in Texas.
Forty are known to survive in Brazoria County, with the culex, or freshwater, and saltwater marsh mosquitoes the most common. Saltwater mosquitos are the most aggressive.
Rainfall does produce some culex mosquitos inland, “but those counts have been very low” because water isn’t standing, Ryan said.
“Many drainage ditches are still dried and cracked,” he said. “Even though we’ve had a lot of rain, most of it is soaking in. If it dries up before the mosquitos go from eggs to adults, it’s all over with.”
Weather permitting, spraying will continue until the outbreak is quelled, he said.
“Historically speaking, things run in about a two-week cycle,” Ryan said. “We have about another week of this activity.”
John Lowman covers Brazoria County for The Facts. Contact him at 979-849-8581.
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Mosquito buzz
• 2,500 species worldwide
• 240 are in the U.S.
• 80 species in Texas
• 40 can survive in Brazoria County
• Culex mosquitoes are common
• Saltwater marsh most aggressive
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