Folks in California may see more mosquitoes in the coming months due to large amounts of rainfall in the state, experts say.
The San Francisco Department of Public Health said there are typically more mosquitoes out from May to November but it’s too early to say how recent storms will impact the mosquito population.
Sarah Wheeler is laboratory director for the Sacramento-Yolo Mosquito & Vector Control District and said mosquitoes need water to complete their life cycle.
One factor that could lead to larger numbers is the increase in rainfall across California recently, she said.
“There’s some uncertainty about what this level of rainfall will do to our mosquito abundance numbers but already, we are seeing mosquito activity in a range of different areas,” she told USA TODAY.
Despite the uncertainty, some areas are preparing for increased numbers anyway, including the San Joaquin County Mosquito and Vector Control District.
Aaron Devencenzi, a district spokesman, said the county expects similar conditions to 2017, when the area saw an excessive amount of rain.
He also said there are many rivers that go through San Joaquin County. As the water travels from mountains to the ocean, it seeps under levees and creates pockets on the sides of these levees.
Those areas will allow mosquitoes to develop along the county’s river systems, he said.
“Nobody has a crystal ball,” he said, but the county expects high numbers of the insects.
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What other factors could lead to higher mosquito populations?
Warmer temperatures also impact populations among mosquitoes, Wheeler said.
Some mosquitoes have been waiting all winter long for warm weather to arrive so they can feed on blood and then lay eggs in pools of water. That has likely already happened, Wheeler said.
“They could be in the water for a month, slowly growing, and then that first population comes off, they take a blood meal, and then they can go out and lay more eggs,” she said. “If there’s more habitat for them to utilize and the temperatures are warmer, then that starting population can start at a higher level.”
What are officials doing to combat higher mosquito populations?
The San Francisco Department of Public Health said it frequently surveys the area for mosquito activity, notes historic breeding sources and works with property owners to eliminate and treat breeding sources as well.
It’s hard to find all of them though, Wheeler said.
“With there being so many more sources, that’s where I think that we probably have a potential for having a larger than normal mosquito population this year,” she said.
With these increased numbers comes a risk for the spread of West Nile Virus, experts say.
The San Francisco Department of Public Health said the area has traditionally seen low West Nile Virus activity but according to Wheeler, the risk shouldn’t be underestimated.
“How many mosquitoes and how much West Nile we’ll see has always been extremely difficult to predict,” she said.
What can residents do to protect themselves?
Extra precautions the San Francisco Department of Public Health suggest include:
- Clearing away standing water on your property such as outdoor containers
- Cleaning out clogged roof gutters and large drains that hold water
- Placing screens under drain covers to prevent mosquitoes from breeding
And don’t forget mosquito repellant, window screens and long sleeves when outdoors at night, the department said.
Wheeler said people should check their own yards to make sure there aren’t any containers full of water. If they find containers of water, dump them out so mosquitoes aren’t drawn to the area, she said.
Also consider wearing long pants and sleeves, putting up screens so the insects can’t get into the house and turning porch lights off so you don’t attract mosquitoes, she said.
“It’s important that they know what strategies they’re going to use to protect themselves from mosquito bites so that if they encounter them when they’re out and about, like at a soccer match or walking the dog, then they’ll be prepared to protect themselves,” Wheeler said.
Saleen Martin is a reporter on USA TODAY’s NOW team. She is from Norfolk, Virginia – the 757 – and loves all things horror, witches, Christmas, and food. Follow her on Twitter at @Saleen_Martin or email her at sdmartin@usatoday.com.