Yellow jackets are medium-sized black and yellow wasps that look similar to honeybees, paper wasps, and mud-daubers.
Yellowjackets can be public health pests because they commonly nest and forage close to people. Because of their territorial behavior and affinity for human food, yellowjackets can restrict or prevent outdoor activities in areas such as campgrounds, picnic areas, and backyards. Unlike honeybees, yellowjackets do not leave a stinger behind, allowing them to be able to sting multiple times. Stings are painful and can be life-threatening in some cases.
The Yellowjacket Life Cycle
Photo courtesy of Napa County Mosquito Abatement District
Yellowjackets are social wasps living in colonies that can contain many hundreds of individuals. Colonies are established every year and abandoned completely as they die off in the fall. Queens overwinter and emerge in early springto begin new colonies.
Nests can be established in trees, in the ground, or other existing cavities such as abandoned rodent burrows, the wall spaces behind an exterior wall and the hollows of children’s play equipment. Nest are made of paper produced by chewing up wood pulp. Populaitons increase rapidly from spring through early fall. During this period of the year, yellowjackets will feed on insetcts, as well as scavenge for sweet and protein-rich foods.
Is it a Yellowjacket?
Yellowjackets are often confused with honeybees, paper wasps, or mud-daubers (sometimes called mud wasps.)
Paper wasps and mud-daubers are rarely aggressive, and are beneficial in the sense that they prey on other insects such as spiders. Yellowjackets, on the other hand, can be very aggressive and can cause serious injury. They have the capability of swarming, since hundreds of insects can live in one nest.
One of the easier ways to tell paper wasps and mud-daubers apart from yellowjackets is the appearance of their nests.
Paper wasp nests and yellowjacket nests are both made out of paper, but they look strikingly different. Paper wasps have smaller nests, with each cell having an opening to the outside.
Paper wasp nest, courtesy of Jayme Frye
Yellowjacket nests are enveloped with layers of paper material, usually leaving only one entrance and exit to the nest. Most yellowjacket nests in Placer County are built underground, making them difficult to see.
Image courtesy of Jackson Carson, 2005.
Mud-daubers, as their name implies, make nests out of mud. Some of these take a long, tube-like shape, and others look like a blob of mud. Mud-daubers are solitary wasps, and do not live in large colonies like yellowjackets.
What Can You Do to Prevent Yellowjacket Problems?
- When dining outdoors, cover food and beverages to discourage yellowjackets.
- Keep garbage cans closed with tight-fitting lids, rinse bottles and cans before placing in covered recycling bins.
- AVOID the area and DO NOT DISTURB the nest.
If You are Stung by a Yellowjacket
- If a stinger is visible, remove it immediately.
- Apply cold water or ice in a wet cloth to the affected area.
- If you are allergic to yellowjackets or experience dizziness, difficulty breathing, widespread sweeling or other symptoms of concern, call 911 immediately.
Integrated Yellowjacket Management
The District will respond to reports of high yellowjacket activity. Technicians will inspect the area and decide if control is appropriate. Control measures may include placing traps or bait, treating nests with an approved insecticide, or physically removing the nest. All pesticide applications are made by state-certified technicians using Environmental Protection Agency (EPA) approved materials.
For more information, click here to download our brochure about yellowjackets.