3 Tips to Reduce the Risk of Mosquitoes and West Nile Virus this Summer

Everyday, the employees of the Contra Costa Mosquito & Vector Control District work to protect public health in Contra Costa County. As summertime is prime time for mosquitoes,
the main focus of our work right now is on reducing the risk of mosquito-borne disease because where you have mosquitoes, you can also have the risk of West Nile virus (WNV). And while we are committed to taking the precautions necessary to reduce the risk of transmitting the SARS-CoV-2 virus that causes COVID-19, which is not transmitted by mosquitoes, we can't let our guard down on WNV. It's important that we Fight the Bite together. 

Here are three simple things to do to reduce the risk of WNV for yourself and your family:
  1. Dump and Drain Standing Water
    • Mosquitoes develop from egg to adult in water. To prevent mosquitoes in the first place, dump out any amount of standing water so that mosquitoes don't have a place to lay their eggs. 
  2. Report Dead Birds
    • Dead birds are often the first sign of WNV in a particular area because WNV is carried by certain birds. Some infected birds (especially crows and jays) die from WNV making it very important to report dead birds. Every report informs District employees to conduct surveillance and control efforts near the location of the dead bird to reduce the risk of WNV, regardless of whether or not the bird can be tested.  
  3. Wear Repellent 
    • When a mosquito bites a bird that's infected with WNV, the mosquito can also become infected. When the infected mosquito bites another bird or a person, it can transmit WNV. By wearing repellent at times when mosquitoes are present you can reduce the risk that an infected mosquito might bite you. 
What to Do if You are Still Being Bitten By Mosquitoes?

If after you have dumped out all of the standing water on your property, you are still being
In a Minute Episode 21: The Importance of Collecting a Mosquito Sample
The Importance of Collecting a Mosquito Sample
bitten by mosquitoes, swat one of the mosquitoes and place it in a plastic bag, and then contact the District to  request mosquito service. While requesting service, you will be asked if you have a mosquito sample. The sample is the dead mosquito in the bag and it will become quite valuable once the District employee arrives to inspect your property. 

The District requests a sample because we have 23 different species of mosquitoes in Contra Costa County alone, and mosquito species vary in their habits. We have mosquitoes that can:
  • Fly short, medium or long distances
  • Lay their eggs in fresh water, salt water, rain water, sewer water, irrigation water and many other types of water sources. 
    • We have mosquitoes that lay their eggs in tree holes that can fill with rainwater. Those are the mosquitoes that can transmit dog heartworm. 
    • We have mosquitoes that will lay their eggs in the soil along our coastal waterways and once tidal water reaches the eggs, they begin developing into day-biting mosquitoes that can fly up to 20 miles. 
Because we have so many different mosquitoes in Contra Costa County that can come from so many different sources of water, the mosquito sample allows the District employee to identify the species of the dead mosquito in the bag and look for the source of those particular mosquitoes.   

So, are you ready to Fight the Bite together?


By dumping out standing water, reporting dead birds, wearing repellent and contacting the District if you are being bitten by mosquitoes, you will reduce the risk of WNV for yourself, your family and your neighbors. 

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To learn when and where we are conducting adult mosquito control, sign up for our mosquito control notifications. Use our interactive map to learn each and every street in our adult mosquito control operation zone each time. 

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