Courtesy of Maricopa County Environmental Services
Maricopa County traps mosquitoes all over the Valley to help control the mosquito population and monitor for West Nile Virus.
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A scourge of mosquitoes

Elizabeth Medora~ 9/24/2014

NORTH VALLEY – A group of mosquitoes is called a scourge – fitting for the discomfort and illness they can bring. The wet weather of the last month has left enough standing water for a bad mosquito season throughout Maricopa County.

“We are experiencing a very busy mosquito season with all the standing water as a result of the recent storms/rain,” said Johnny Diloné, Media & Community Relations Manager of Maricopa County Environmental Services. “In just two days (Sept. 15 and Sept. 16) our Vector Control Division received over 1,000 mosquito-related complaints. We expect the week of Sept. 14-21 to end up being the most busy or at least one of our most busy weeks ever.”

The good news is the majority of the mosquitoes the county’s Vector Control are seeing are ‘floodwater mosquitoes,’ which Vector Control says are not known to carry any diseases. These mosquitoes reproduce rapidly in standing water. They also fly during the day.

“The mosquitoes that would most likely carry West Nile Virus are the Culex type of mosquitoes, which fly during dawn and dusk,” Diloné explained. “These are seen in single numbers and they need stagnant water for 3-4 days to lay down their eggs and for these to hatch-up and adult mosquitoes to follow after a few more days.”

While floodwater mosquitoes aren’t a health concern as Culex mosquitoes are, Maricopa County considers resident reports regarding any mosquitoes important.

“If the public notices adult mosquitoes or mosquito breeding in their area, they should contact Maricopa County Environmental Services Department and submit that Complaint in order for us to investigate,” said Diloné. “We are complaints-driven, so as we learn about mosquito-related problems, we will respond to complaints and set up mosquito traps in those areas that we may not be already monitoring.”

Diloné noted that the county has over 640 active mosquito traps and is setting up more to test for West Nile Virus and keep it controlled.

“This proactive approach has helped us have a better control of the mosquito situation/problem and has helped minimized the risks of WNv in our communities,” Diloné added.

The ‘scourge’ doesn’t just affect humans – mosquitoes bite pets, too, and can carry heartworms.

“Mosquitoes carry the baby form of heartworms called microfilaria,” said Dr. Marlayna Barnard of the Animal Hospital at Anthem.

The mosquitoes’ blood-sucking action “transmits between dogs and other dogs, coyotes, bobcats, etc.” and “injects them with these baby microfilaria,” Barnard explained. The baby heartworms mutate until they are adults and breed inside their host animal.

“The heartworms sit in the heart and pulmonary arteries,” Barnard said. “Dogs can have 200-250 worms. These heartworms can cause heart failure, cough, lethargy, and fever.”

Cats can get heartworms, too, but it’s less common. Dogs are the most at risk.

“I hear people everyday say, ‘I’ve never worried about heartworms in Arizona,’” Barnard related. She noted that Arizona saw an increase in heartworm cases after Hurricane Katrina; many infected dogs were transported around the country, and the mosquitoes began transmitting heartworms to previously healthy pets.

One to five heartworms cases per Arizona veterinary clinic were reported in 2013.

“The American Heartworm Society estimates one million dogs have heartworm disease today,” Barnard said.

Heartworms can be treated, but it’s difficult and risky. Infected dogs can have an injection that kills the worms, but when the worms die, they dump into the lungs, which can block the dog’s breathing. Surgery is another option – a pet cardiologist can scope through the dog’s jugular vein and physically remove the worms.

Prevention is the best way to protect dogs from heartworms, including monthly pills and biyearly injections available from vet clinics. Dogs not on these medications should have a heartworm test if their owners think they may have bitten by mosquitoes.

“ The sooner the better,” Barnard said regarding heartworm detection, since treating the heartworms before they can breed helps ensure the dog’s survival.

Along with heartworm prevention pills, Barnard recommended, “keeping pets inside as much as possible, getting rid of any stagnant water around your property, and taking measures to control mosquitoes through pest control” as ways to protect your pet from heartworms.

For more information about heartworms, Barnard recommends the American Heartworm Society,

Much as for pets, prevention is the key for people to avoiding mosquito-related illnesses. Maricopa County urges residents to try to avoid outdoor activities at dusk and dawn when disease-carrying mosquitoes are most active. If you must be outdoors, wear long pants and a long-sleeved shirt.

Getting rid of standing water keeps the mosquitoes from breeding. Residents are asked to dump stagnant water in fountains, birdbaths, flowerpots, and other containers. Green pools are a health hazard and need to be cleaned out, too.

For more information on mosquitoes, to report standing water or green pools, or to report concerns of mosquito-related illness, visit or call (602) 506-0700.