Skip to main content

January 2022 Newsletter

Person in tan uniform holding a clear plastic bag with water and several very small brown fish
Technician Sean prepares mosquitofish for a resident.


Mosquitofish are small guppy-like fish that can eat several hundred mosquito larvae each day.  The District uses mosquitofish as part of our Integrated Vector Management (IVM) strategy (learn more about IVM here and here).  Mosquitofish are useful in non-natural sources, like decorative fish ponds, water features, and un-used ‘green’ swimming pools.  (Mosquitofish can NOT be placed in water where they may escape into natural water sources.)  To learn more about mosquitofish, click here.  To request a vector control technician visit your property to see if mosquitofish might be a good option for you, click here.



Don't Let a Tick Make You Sick!

Hiking is a popular activity during these sunny days – don’t let ticks ruin your fun! We are entering the peak months for tick adult activity in San Mateo County. There is not necessarily a higher risk of tick-borne disease in San Mateo County compared to previous years; however, ticks are present and the diseases they carry can be very serious. Learn how to prevent tick bites here.

Click on the tick below to see a video of a tick 'questing' (waiting for a host) and crawling onto a person.


Mosquito Surveillance

Adult Mosquitoes

Current abundances of all adult mosquito species are low and consistent with the five-year average. The abundance of adult mosquitoes is expected to remain low until spring. Read more about mosquito surveillance here.

A person standing in knee-deep water in a forest hold a mosquito dipper (long pole with a white cup on the end). The person peers into the cup to see if there are mosquito larvae. The person is wearing a tan uniform shirt, blue pants, and hip waders.
Technician David checks a willow marsh for mosquito larvae.

Larval Mosquitoes

In December, 115 larval samples were collected in the field by vector control technicians and submitted to the lab. Seasonal rain has kept freshwater impounds and marshes full of water, turning them into active and potential mosquito breeding sources. A District vector control technician uses a dipper to take a sample of the water and visually inspects it for mosquito larvae. If larvae are present, the technician transports the sample to the laboratory for counts and identification. Read more about mosquito surveillance here.


Service Requests

The most common service requests in December 2021 were for rodent inspections, mosquitoes, and yellowjacket nest treatment/removal.

Read more about service requests here.

West Nile Virus

West Nile virus activity is generally very low during the winter months. For up-to-date information about West Nile virus in California during the winter, visit CDPH's website.

Join our mailing list