Aedes aegypti mosquitoes discovered all through Ventura County


Tom Kisken

| Ventura County Star

Why should you worry about mosquitoes?

Learn how to protect yourself from mosquitoes and the health threats they pose, such as the Zika and West Nile viruses.

After first appearing in Ventura County less than a month ago, potentially dangerous Aedes aegypti mosquitoes have now been found in east and west Ventura, Fillmore, Westlake Village, Piru, Thousand Oaks and Simi Valley.

Unconfirmed reports of the mosquito have also come from other communities, including Camarillo and Santa Paula.

“We expect more reports from across the county,” said Cary Svoboda, program director for the vector control program for the Ventura County Environmental Health Division. “They’re just very good at moving around and getting their foot in the door.”

The mosquitoes are a concern and urge residents to drain stagnant water as they can carry potentially dangerous viruses such as zika, dengue fever, chikungunya and yellow fever.

Are there any documented cases so far?

There are no documented cases of such transmission in California, but officials say the chances will increase if the spread of the Aedes aegypti and another potential carrier of the virus, the Aedes albopictus mosquito, continues across California.

They fear the mosquitoes could become carriers by biting returning travelers who have been infected in other parts of the world where the virus is more common, including Central America, Mexico and Asia.

The Aedes aegypti mosquitoes are also known as yellow fever mosquitoes. They are small and black with white stripes on their backs and legs. They are unusual because they bite during the day.

More: Invasive Aedes mosquito species first found in the county that are creating health concerns

“They have a lot of preference for the lower leg, especially around the ankle,” Svoboda said of biting habits that are often repetitive and target parts of the body that are more likely to have a successful blood meal. “You also bite behind the elbow on the back of your arm.”

When was the Aedes mosquito first spotted in Ventura County?

Mosquito control specialists have been fishing for the Aedes aegypti for about five years, with no finds in Ventura County. That changed on September 9th when one of the mosquitoes was discovered in the Simi Valley, the first of many traps in the city.

Officials reported last week that an Aedes aegypti was also trapped in Thousand Oaks. The mosquito is now being found across the county, and many other residents report bites to the county’s mosquito hotline.

The Aedes albopictus, also known as the Asian tiger mosquito, has not yet been found in traps in Ventura County.

Svoboda said it was possible that the Aedes aegypti mosquitoes made it “under the radar” to the county and that their development and spread was accelerated by hot and humid weather in August.

It’s not an unprecedented story. In Shasta County, Northern California, the Aedes aegypti was also found for the first time this summer and has now been identified in several different locations.

What are officials doing to contain the spread?

The spread could be amplified by the time of year, with August and September being the peak seasons for the Aedes aegypti, said Peter Bonkrude, district manager for the Shasta Mosquito and Vector Control district.

The first discovery also spurs efforts to capture the insect and identify breeding grounds. This often means more mosquitoes are discovered.

Bonkrude said the Aedes aegypti was not a particularly skilled flyer, but could move when a container of mosquito eggs was moved from one place to another. This list could include flower pots, plants with flowers that drink water, empty tires, cans, lids, bird baths, ornamental fountains, toys, or anything else that can hold stagnant water.

Svoboda said it was possible for the mosquitoes to hatch in underground sewers as well.

In Ventura County, environmental health officials are sending postcards and brochures to neighborhoods where the mosquitoes have been found. They run inspection posts for potential breeding grounds and in some cases use biological larvicides.

What should I do to prevent Aedes mosquito bites?

They say the most important thing is that they urge residents to clear any standing water from their property and, if possible, get rid of the container the water was in.

“This is to be deflated and drained,” said Ron Ventura, director of the county vector control program.

People should also:

  • Contact your doctor if they get sick or react to bites.
  • Report Aedes aegypti bites and known breeding sites to the district’s mosquito hotline at 805-658-4310.
  • Use tight-fitting screens and tight-fitting doors to keep the mosquitos out.
  • Wear long-sleeved shirts, long pants, socks, and shoes.
  • Use an EPA approved insect repellent.

The Aedes aren’t the only ones affecting mosquitoes

The aedes aegypti is not the only problem for vector control specialists. The season for the West Nile virus, which can be transmitted by some Culex mosquitoes, often starts in September. To date, no reports of the virus have been confirmed in animals or humans in Ventura County.

The occurrence of mosquito season in the middle of a pandemic has also raised questions about whether the insects can carry COVID-19.

All current research suggests the answer is no, said Bonkrude, president of California’s Mosquito and Vector Control Association.

More: Pools left behind in Woolsey Fire are triggering mosquito control

The way to deal with invasive Aedes mosquitoes is to get involved and take steps to reduce the risks, Bonkrude said.

“The mantra is always not panic, but be prepared,” he said.

Areas where Aedes aegypti mosquitoes have been trapped include: areas in the Simi Valley with the most finds east of Erringer Road, the Lynn Ranch portion of Thousand Oaks, the area near the intersection of Hillcrest and Duesenberg in the Westlake Village area near Bristol Road and Montgomery Ave. in Ventura, the Ventura Avenue portion of Ventura, the west side of Fillmore, and the Main Street portion of Piru.

Tom Kisken covers health care and other news for the Ventura County Star. Reach him at or 805-437-0255.

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