Post Tara Roth, Ph.D.

Ticking All the Boxes: the Amazing Variety of Ticks in San Mateo County

At the District, the majority of our tick surveillance focuses on three tick species, Ixodes pacificus, (western black-legged tick), Dermacentor varabilis, (American dog tick) and Dermacentor occidentalis, (Pacific coast tick).  These ticks quest for hosts in the vegetation along trails, and are easily picked up by hikers and dogs. While these three species present the greatest risk of disease transmission to humans and pets, there are many more species of ticks that live in San Mateo County that we do not collect as part of our usual surveillance.

Post Tara Roth, Ph.D.

Four Things Should Know About Rabies

Rabies has achieved somewhat of a boogeyman quality due to its high risk of death and tendency to invade the nervous system but did you know that this frightening disease is actually very rare in California?

1. Rabies is very dangerous.


November 2018 District Newsletter

New from the District in November: Tick Season is Here

Click here to read the November 2018 District Newsletter.


Farewell to Laboratory Seasonal Alexander Flores

This summer, the laboratory has been assisted by Alexander Flores, who conducted most of the surveillance for invasive Aedes mosquitoes this season. For the past five years, Alex has worked for the District as a seasonal technician in the Operations department. This year he took a position in the Laboratory department for a new experience. Alex started the summer as the invasive Aedes technician, funded by a grant from Public Health Foundations Enterprises, Inc. on behalf of the California Department of Public Health.


October 2018 District Newsletter

New from the District in October: Creepy Creatures

Click here to read the October 2018 District Newsletter.


Termites: Always A Scary Discovery

Autumn is the time of year for termite swarms as adult winged termites (called alates), leave their colonies, mate, and establish new colony sites. Residents often see the swarms around their neighborhood or find discarded wings and dead termites scattered on the ground or caught in spider webs. Only a very small proportion of termites are successful in establishing a new colony.

Photo gallery Megan Sebay

Coastal Cleanup Day 2018

It’s that time of year again: Coastal Cleanup Day! On Friday, field operations supervisor Casey and seasonal staff members Evan, Devon, and Justin did their part to keep San Mateo County beautiful by removing some trash from the shoreline.

Press release

California Department of Public Health: CDPH Confirms First Two Human West Nile Virus Deaths of 2018

Sacramento, CA – Sept. 10th, 2017

The California Department of Public Health (CDPH) announced today two confirmed deaths in California due to West Nile virus (WNV). The deceased persons were residents of Glenn county and Yuba  county.

“We are still in a peak period of West Nile virus transmission in the state so we urge everyone to take every possible precaution to protect themselves against mosquito bites,” said CDPH Director and State Health Officer Dr. Karen Smith.


September 2018 District Newsletter

New from the District in September: Head Lice Head Back to School

Click here to read the September 2018 District Newsletter.

Blog post Tara Roth, Ph.D.

When What’s Bugging You Isn’t A Bug

Here at the District, we examine hundreds of samples every year that are submitted by residents in response to some kind of irritation – a bite, a rash, or some other skin reaction. An entomologist from the District laboratory will work with the responding technician to find the culprit of the bites and help the resident develop a plan to stop the infestation. But what happens when those samples come back bug-free and no evidence of an infestation can be found?

Blog post

We Fly So Mosquitoes Can’t

Each summer, San Mateo County Mosquito and Vector Control District uses a helicopter to treat three local freshwater marshes – Annex Lake, Mills Field, and Sharp Park Golf Course – for mosquito larvae. This process is called ‘larviciding’. These treatments are conducted to prevent the emergence of thousands of mosquitoes that have the potential to put the surrounding communities at risk of West Nile virus transmission.

Blog post

Headlice Head Back To School

This time of year, you may soon find yourself going head-to-head with a common parasite. Head lice can infest anyone, but are most common among young children during physical contact while playing or reading together. Less commonly, lice can be spread when sharing bedding, clothing, hats, or hair accessories.

Blog post

National Preparedness Month

September is National Preparedness Month, a time when families are encouraged to make plans and gather supplies to prepare for natural and man-made disasters. Many families will already have an emergency plan or an earthquake kit, but we bet you haven’t planned for animal and insect hazards after a disaster.


Post-Treatment Disease Surveillance Finds No West Nile Virus in Mosquitoes Trapped in East Palo Alto

The District laboratory has found no further sign of West Nile virus in mosquitoes trapped in areas of East Palo Alto after this week’s adult mosquito control treatment.


Spiders: Not So Creepy After All

Unlike mosquitoes, which feed on humans and seek them out, spiders have no interest in biting you, and will only do so if they are being crushed or otherwise threatened. Small spiders are unable to break the skin, but even the bites of larger spiders are largely harmless. In fact, most ’spider bites’ turn out to be something other than a bite - such as a serious bacterial infection or even skin cancer!


Where the Wild Things Shouldn’t Be
Living With Your Wild Neighbors

We’ve heard from a few residents lately that are sick and tired of their neighbors’ wild partying. They’re reporting garbage strewn across the lawn, noise at all hours of the night, and even uninvited visitors making themselves at home in the attic! Yes, we’re talking about those neighbors: the animals that live in our neighborhoods.


August 2018 District Newsletter

New from the District in August: Local Wildlife, Friendly Spiders, and More.

Click here to read the August 2018 District Newsletter.


July 2018 District Newsletter

New from the District in July: West Nile Virus Season in the Bay Area

Click here to read the July 2018 District Newsletter.


Yellowjackets and Paper Wasps

During the summer months, the District receives numerous calls regarding yellowjackets and paper wasps. These social wasps both have yellow and black markings and are common in San Mateo County, but they have important behavioral differences.

Image from

Don’t Let Dermacentor Ticks Make You Sick

It’s summer and that means peak season for the dog tick and Pacific coast tick (collectively called Dermacentor ticks)! These large, brown-colored ticks are very prevalent this time of year along the edge of trails and in brushy areas with tall grass all throughout California. Unfed, they can be nearly three times as large as the black-legged ticks that are prevalent during the winter and spring and can engorge to the size of a grape if left attached to repletion.