These table and graphs show the average number of mosquitoes collected per CO2 trap per night during the month of November compared to the five-year average for the six most common mosquito species in San Mateo County. Counts for all species continue to decline as we progress into the cooler season. All species are near or slightly below average for this time of year.
This table contains the number of each type of service request in November 2018 compared to the three-year average in November. The total number of service requests is somewhat below average, mainly because we have had fewer than typical mosquito-related requests. The number of yellowjacket and wasp service requests continued in a steep decline, shown in the graph, and will likely remain low until spring.
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.
District laboratory staff conducted a rodent survey for hantavirus with California Department of Public Health (CDPH) staff on June 4-5 in La Honda. Peromyscus truei (pinyon mice) and Peromyscus californicus (parasitic mice) were trapped and blood samples were taken for testing. Kidney samples from any mice with positive blood samples will also be tested by the CDPH to be used for a study of the geographical distribution of different hantavirus strains in California.