Increase in Bay Area wasp population is posing threat to residents: How to avoid getting stung

Did you know wasps can sting you multiple times and bite?

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Thursday, August 28, 2025
Wasps can sting multiple times and bite, Bay Area expert says

SAN MATEO COUNTY, Calif. (KGO) -- Officials are reporting an increased number of wasp sightings throughout the Bay Area.

San Mateo County officials sent out a warning about the increased wasp population at parks, including Pillar Point Bluff right outside Half Moon Bay.

The San Mateo County Mosquito & Vector Control District posted this week on Facebook: "We've gotten almost twice as many service requests for yellowjacket nests as usual."

And offering to help for free if you know the location of the nest.

The wasp sightings are not limited to San Mateo County.

Samuel P. Taylor State Park in Marin County posted about the higher than normal population of yellowjackets on their Instagram page, saying there's increased access to water and food sources.

"We have had a cooler than normal summer, which I know that most folks have read about, seen about and other things like that," said Peter Ostroskie, of the California State Parks Bay Area District. "So with those cooler temperatures, it allows for the population to kind of grow so if there's no like, absolute really big heat days and there's no cool days, then the wasps actually have this perfect kind of incubation period of creating more and more of the population."

MORE: 'A lot of wasps': Marin County park warns visitors about increased wasp activity

Unusually large populations of Yellow Jackets are impacting different areas including Samuel P. Taylor State Park in West Marin.

San Mateo County has tips including:

  • Do not disturb yellowjacket nests

  • Cover sweet drinks with lids

  • Avoid going barefoot outdoors

Ostroskie said wasps are different than bees.

"When a bee stings you, they're using their stinger once and then usually the bee will die after they've used their stinger," Ostroskie said. "Wasps actually can sting multiple times and they bite, so they are much more resilient in that side of it. And if you do get bitten or stung by a wasp and you know that you need to seek medical attention, we're asking folks to please seek that."

If you have an allergic reaction, you should seek medical attention.

Ostroskie is also recommending not putting up wasp traps within campgrounds because they have a pheromone that can actually attract the wasps more.

The San Mateo County Mosquito & Vector Control District said in the prior 5 years, they had received about 600 yellowjacket-related requests by this time each year. The number of requests this year so far is nearly double at over 1,000.

MORE: Man dies after swarm of bees attacks him on porch of his own home

The district said yellowjackets can be found throughout San Mateo County, with more calls coming from the coast and from the mid and southern parts of the County - San Mateo, Redwood City, Woodside, Portola Valley.

Anyone in San Mateo County can request help with a yellowjacket nest from the San Mateo County Mosquito & Vector Control District if they know where the nest is located.

They can submit a request online or by calling 650-344-8592.

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