Ada County To Spray Populated Areas From The Air To Kill Mosquitoes

Jul 7, 2015

Later this week, Ada County will take to the skies to spray for mosquitoes.  The spraying will occur Thursday after 8 p.m. over east Boise, and in Eagle and Star.

Mosquitoes in Canyon and Gem Counties have tested positive for West Nile Virus, and Ada County mosquito abatement officials say it’s only a matter of time before the potentially deadly disease reaches the state’s most populous county.

Ada County Weed, Pest and Mosquito Abatement Director Brian Wilbur says without early, aggressive action, this year could be the worst for West Nile Virus since 2006. That's when more than 20 deaths were linked to the disease in Idaho. Wilbur says the hot, dry weather is to blame.

“The reason is simple: West Nile is an avian disease carried by infected birds,” he says. “The lack of water concentrates the birds around fewer watering areas allowing vector mosquitoes more contact with the infected birds and greater ability to infect other birds who will spread the disease before they die." 

While mosquitoes need water to breed, Wilbur says hot weather increases the speed at which they hatch. Wilbur says Ada County traps have caught more than five times the average number of mosquitoes so far this year. He says the kind of mosquitoes that carry West Nile are doubling each week. 

But Wilbur says aerial spraying over populated areas has caused concern among Ada County residents in the past. He says there are risks involved, but West Nile is a greater risk.

“I ask [people concerned about aerial spraying] to look at the disease and look at the people who’ve had it,” Wilbur says. “I have personal experience with loss through death from West Nile Virus. And I’ve watched that process very closely in our own family. You really don’t want that to happen to other people around you.”

Wilbur says his son-in-law’s mother was killed by West Nile.

Ada County will pay private contractors more than $21,000 to spray the pesticide Dibrom Concentrate over 15,000 acres, much of which is residential property.

Dibrom uses an organophosphate called naled. In high doses, naled will kill most anything with a central nervous system. But the EPA says in the concentration used for mosquito control it does not pose “unreasonable risks to human health or the environment.” It’s been approved for use in populated areas since 1959.

“Naled can be used for public health mosquito control programs without posing unreasonable risks to the general population when applied according to the label. We have estimated the exposure and risks to both adults and children posed by ULV aerial and ground applications of naled. Because of the very small amount of active ingredient released per acre of ground, the estimates found that for all scenarios considered, exposures were hundreds or even thousands of times below an amount that might pose a health concern….. However, at high doses, well above those for normal labeled uses, naled like other organophosphates, can overstimulate the nervous system causing nausea, dizziness, or confusion. Severe high-dose poisoning with any organophosphate can cause convulsions, respiratory paralysis and death. Naled used in mosquito control programs does not pose unreasonable risks to wildlife or the environment. Naled degrades rapidly in the environment, and it displays low toxicity to birds and mammals. Acute and chronic risk to fish is not expected, but there is potential for risks to invertebrates from the repeated use of naled. Naled is highly toxic to insects, including beneficial insects such as honeybees.” – EPA

The toxicity to bees is often considered the biggest danger of naled-based pesticides. Wilbur says spraying at night will help reduce bees' exposure. People with gardens in the path of the spray are cautioned to wash fruits and vegetables before eating them.

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