What to do if You are Face-to-Face with Ground-nesting Yellowjackets in Your Yard


“I was minding my own business, mowing my lawn when all of a sudden, I’m being attacked by yellowjackets.”

Does this sound familiar? Contra Costa County residents often share stories like this when a Contra Costa Mosquito & Vector Control District employee arrives to provide residential ground-nesting yellowjacket service. This year, they are stories that we’re hearing more often.

So far this year, the number of ground-nesting yellowjacket service requests that the District has received has surpassed last year’s number by 21 percent as well as the average for the last five years by 74 percent.

That’s left residents and District employees alike to wonder why are there so many yellowjackets this year?

“The mild winter may have allowed more hibernating queens to survive. Then, the late season rains provided plenty of vegetation for the smaller insects that the yellowjackets will feed on. The combination has left us with a bumper crop of yellowjackets this summer,” says the District’s Scientific Programs Manager Steve Schutz, Ph.D.

What to do if you encounter a ground-nesting yellowjacket nest on your property

  1. First and foremost, if the yellowjackets are biting and stinging you, remove yourself from the location.
  2. Once you are out of the yellowjackets’ path, draw a rough map of the yard, pointing out the location of the nest, so that the District employee who responds to the request will know where to look.
  3. Place the map on the front door or front gate.
  4. Contact the District for ground-nesting yellowjacket service by calling 925-685-9301 or by visiting our website.

Once you have requested the District service, do not attempt to do anything to the nest. The nest must be dry and untreated should the District need to treat it.

The District does not make appointments. Once we receive a request, we will respond within five business days.

About Kevin

Councilmember - City of Oakley, Manager of Mainframe Operations and Optimization – USS-POSCO INDUSTRIES, Co-Founder and Board Member - Friends of Oakley A Community Foundation, Commissioner - Contra Costa Transportation Authority, Board Member - Tri Delta Transit, Transplan, San Joaquin Joint Powers Authority and RD 2137, Advisory Board – Opportunity Junction
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