Yellowjacket Identification

There are many species of wasps found in San Mateo County. Most species are solitary, non-aggressive, and rarely seen. However, some species may cause annoyance or harm to humans.

A computer-generated image of the side, underground view of a yellowjacket nest. The entrance to the tunnel is at ground level, in between blades of green grass. The tunnel goes down into the brown dirt until it forms a large round space. Inside the space is the nest, which is connected to the wall of the hole by being connected to a root. The inside of the nest has dozens/hundreds/thousands of little cells for the queen yellowjacket to lay eggs in. The cells are surrounded by a covering that protects the nest. The nest can be entered through a hole in the bottom of the nest.

Yellowjacket Nest Treatment

The District provides no-cost control for ground nesting yellowjackets when the location of the nest is known. A yellowjacket nest site looks like a small hole in the ground with many yellowjackets flying in and out. Without disturbing the nest, mark its location with a flag or other object so that the technician who comes to treat it will be able to find it.

May contain: wasp, bee, andrena, hornet, invertebrate, insect, and animal

Yellowjackets

Yellowjackets are stinging insects that build large communal hives.

Photograph of a paper wasp nest - it is in the corner of the exterior of a building, there are several wasps on the nest, a pattern of honeycomb-like cells can be seen, with some of them white/capped.

Paper Wasps

Paper wasps build very distinctive nests with open combs in an umbrella shape that are usually attached by a small stalk (called a petiole) in the eaves of houses. With striking black and yellow coloring, these wasps are often confused with hornets because they have long bodies and legs with an elongated waist that gives them an hourglass like appearance. Unlike yellowjackets and hornets, paper…

Bees

Bees are sometimes mistaken for yellowjackets or wasps. Here are some similiarities and differences:

Other insects with stripes or stingers

We have a wide variety of bees and wasps in San Mateo County. As the weather warms up, these insects become more active and more numerous in yards. Although capable of stinging, most species are non-aggressive, and only sting defensively when their nests are threatened.

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