The yellowjacket population is surging in both the East Bay and North Bay this summer, and since the bugs are very aggressive and can sting multiple times, county authorities have their hands full cleaning out an unusually large number of nests.

Folks who attend the Outside Lands music festival may recall that in 2024, there was something of a wasp infestation, with the insects swarming food stands and generally giving festivalgoers a serious hassle. We had not seen volumes of wasps of that level in the past.

Fast-forward to this summer, when KRON4 reported in August that Contra Costa County was experiencing an invasion of yellowjackets, with complaints to the county about double what they’d be in a normal year. And then on Monday, KRON4 pointed out that Marin and Sonoma counties are also experiencing an unusually large yellowjacket invasion, with complaints about nests — and attacks — coming in unprecedented numbers.

“This year so far we’ve had about 5,400 [calls] from the public to control in-ground yellowjacket nests,” Marin/Sonoma Mosquito & Vector Control District spokesperson Nizza Sequeira told KRON4. (Yes, there is a Marin/Sonoma Mosquito & Vector Control District.) And much like last year, a relatively mild winter has led to something of a population boom this year for yellowjackets.  

Yellowjackets nest in the ground, so people (and pets) generally do not realize when they are encroaching on these nests, and unleashing angry swarms. And these yellowjackets are very aggressive, capable of stinging multiple times. Plus if you get stung by one of the wasps, the scent of that sting will just make more yellowjackets identify you as an enemy and then simply sting you more.

“They are going to start stinging you, biting you,” Sequeira said to KRON4. “They even tend to mark you and that is like an alarm bell to all the other yellowjackets and they will begin to come out and attack you as well.”

At this time of year, yellowjackets aren’t just protecting their nests, they’re also looking for carbohydrates. Officials advise that you should keep tight lids on trash and compost bins, and if eating outdoors, keep lids on any containers of carbohydrates and/or sweets.

Marin, Sonoma, or Contra Costa county residents can simply call the county if there are suspected nests they want to see removed. Though if anyone happens to be allergic to yellowjacket stings, it's recommended you call 911 immediately if stung.

Related: The Most Unwelcome Guests at This Year's Outside Lands: Wasps [SFist]

Image: A macro shot of a yellow jacket on its nest (Getty Images)