September 2025 Newsletter

Staff highlights - Vanessa and Eric

We are fortunate to have dedicated staff passionate about protecting San Mateo County residents from mosquitoes and the diseases they can carry. We'd like to let you get-to-know our staff and why our staff love their work. This month, we are highlighting Vanessa and Eric.

Click here to learn more about Vanessa Hernandez Pacheco, Vector Control Technician

Click here to learn more about Eric Eckstein, Vector Control Technician

A person in a beige uniform and cap, standing outdoors, with patches and labels on the shirt. Trees and blue sky in the background. — Vector Control Technician Vanessa

A person smiling, wearing a "San Mateo County Mosquito & Vector Control District" jacket and cap, standing outdoors. — Vector Control Technician Eric

A person in a beekeeping suit handles a bee swarm on the ground in a grassy area, with a shovel nearby. — Operations Director Casey wears a protective suit to apply a pesticide dust directly into a yellowjacket nest entrance.

Yellowjacket Requests Reach an All-Time High in 2025

A top-down view of a yellowjacket. The insect has two black antenna, a body with yellow and black stripes, 6 yellow legs, and two light colored wings.

This year has been a particularly busy year for yellowjacket nests! Staff have responded to more than twice as many calls as is usual for this point in the year. As of August 31, staff have responded to 1,156 requests in 2025 – more than the first 8 months of any of the previous 10 years.

Yellowjackets are a kind of wasp; they can sting and bite. They aggressively defend their nests, and some people are very allergic to their stings.

A computer-generated image of the side, underground view of a yellowjacket nest. The entrance to the tunnel is at ground level, in between blades of green grass. The tunnel goes down into the brown dirt until it forms a large round space. Inside the space is the nest, which is connected to the wall of the hole by being connected to a root. The inside of the nest has dozens/hundreds/thousands of little cells for the queen yellowjacket to lay eggs in. The cells are surrounded by a covering that protects the nest. The nest can be entered through a hole in the bottom of the nest. — One of the most common types of yellowjackets in our area builds its nests underground.

We can help (for free!) if you know the location of the nest. Some tips and info...

Yellowjackets are most active between about 10am and 4pm. Check for the nest during this time frame.
Our most common yellowjackets live in holes in the ground. Sometime the holes are hidden by ivy and other plants.
Yellowjackets enter and exit the hole looking like planes landing and taking off from an airport. Like a tiny SFO!
Placing a small flag or other marker near the nest entrance will help our staff quickly treat the nest when they arrive. Be careful! You should NOT place the marker directly on the nest - in the general area is fine!
Call 650-344-8592 or submit a request online at https://www.smcmvcd.org/request-service
Our staff typically visit the next business day. If you've marked the nest, then you don't even need to be home when we stop by to treat the nest.

West Nile Virus Updates - Stay Informed

Current West Nile virus information for San Mateo County

As of early September, residents have reported 453 dead birds in San Mateo County to the West Nile Virus Call center (https://westnile.ca.gov/ or 1-877-WNV-BIRD). Of those, 130 were in testable condition and tested in our laboratory. None of the dead birds collected in San Mateo County have tested positive for West Nile virus so far in 2025. Visit our webpage to stay up-to-date with San Mateo County information. To stay up-to-date with statewide information, visit the webpage with California state-wide data.

No mosquitoes have tested positive for West Nile virus yet this year in San Mateo County. As of early September, our staff have collected and tested over 2,000 mosquitoes in 2025. West Nile virus has been found in mosquitoes in other counties in Calfornia, so if you are traveling don't forget to take your mosquito repellent and follow other tips to prevent mosquito bites and the diseases they can spread.