Mosquitoes are a year-round problem in Contra Costa County.
Per Steve Schutz, Ph.D., scientific program manager and entomologist, “In the Bay Area we do see some level of mosquito activity year-round, and there are a few species that are primarily active during the winter (the risk of virus transmission at this time is very low) and early spring. Although temperatures may fall below freezing outside, sheltered locations like underground drains may stay much warmer.
Also, although some of Contra Costa County’s 23 mosquito species become inactive (‘hibernate’) during the winter, they still occasionally emerge from their hiding places on warm days. Scientists believe West Nile virus re-emerges each year when mosquitoes infected during the previous season leave their hiding places in the spring to re-initiate the transmission cycle.”
