Skip to main content

As mosquito trap numbers fall, positive West Nile virus samples rise

Mosquito trap data from sgvmvcd

August 17 to 21

May contain: plot
Dotted line shows three-year average

We heard a rumor... that mosquit​​oes are getting bit all over San Gabriel Valley! Who's biting, you ask? Humans!

Your efforts to Bite Back and Tip, Toss, Protect are truly paying off. While our staff tackles the outdoor, public spaces, we truly appreciate you wrestling your yards and patios away from mosquitoes.

Last week (August 17-21), our Surveillance Department's mosquito traps displayed yet another low count in mosquitoes.

This hard work is vital as West Nile virus (WNV) moves through San Gabriel Valley during the warm-weather months. As of last week, mosquito samples from Rosemead, Basset, and El Monte tested positive for WNV. This is first confirmation of WNV in 2020 in Bassett and El Monte.

WNV tranfers to humans through the bites of Culex female mosquitoes


Blood feed of a Culex female mosquito, infamous transmitters of West Nile Virus
Blood feeding of a Culex female mosquito: An infamous transmitter of West Nile Virus

While we can expect WNV cases to rise, it's essential to maintain the upper hand over these pesky insects by staying in the loop:

Receive E-alerts on the lastest mosquito news in SGV

Track West Nile Virus activity in your community

Stay informed on InstagramFacebook, & Twitter

With that, stay vigilant SGV! Keep an eye out for potential mosquito breeding sites in your community, like those shown below.

Our confidential tip line service allows residents to anonymously report breeding sources.


West Nile Virus Update: Seven mosquito samples and one dead bird in San Gabriel Valley tested positive for West Nile Virus so far this year. Track activity in your community.