The District laboratory currently collaborates with the Stanford
Division of Pediatric Infectious Disease to test mosquito samples
collected internationally for diseases such as chikungunya and
Ants are common household pests. They don’t carry
disease, but can be annoying.
Argentine ants are the most common cause of ant invasions
indoors, but other species may cause problems in this area.
Knowing which ant is causing your issue is important, since
different ant species have different food preferences and will
take different types of bait. For ant identification and control
information, contact the District laboratory at (650) 344-8592.
Mites are small pests barely visible to the naked eye. In
California, the most common biting mites include the tropical rat
mite, the northern fowl mite, and the chicken mite. They feed on
rodents, birds, and fowl and occasionally infest homes and bite
humans once their host has left the area.
Some mite species may also be found outdoors. These mites do not
typically infest homes, but people may be bitten while spending
time outdoors, especially in tall grass or brush.
Although many people are afraid of spiders, virtually all the
spider species found in San Mateo County are harmless to humans.
Unlike mosquitoes, which seek out and feed on people, spiders
have no interest in biting us, and will only do so in
Spiders that find their way indoors can be gently relocated
outside (you can scoop them up using a piece of cardboard and a
container, or vacuum them up and empty the canister outside), or
squashed if you prefer. Sealing up cracks and other entrances to
your home will keep spiders, as well as other pests, from coming