Yellowjackets 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.
Yellowjacket or Paper Wasp?
Yellowjackets are often confused with paper wasps.
Size and Appearance
Paper wasps have slender, segmented bodies with a thin waist and orange-tipped antennae.
Yellowjackets have short, thick bodies with black or black and yellow antennae.
Paper wasps are rarely aggressive and are beneficial in the sense that they prey on other insects such as spiders.
Yellowjackets can be very aggressive and cause serious injury when swarming to defend their nest.
Paper wasps dangle their long legs when they fly.
Yellowjackets tuck their legs under their bodies when they fly.
One of the easier ways to tell paper wasps 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. The nests are often found under eaves or roof tiles.
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 locate
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 spring to begin new colonies.
Nests can be established in trees, the ground, or in other existing cavities such as abandoned rodent burrows, the wall spaces behind an exterior wall and the hollows of children’s play equipment. Nests are made of paper produced by chewing up wood pulp. Populations increase rapidly from spring through early fall. During this period of the year, yellowjackets will feed on insects, as well as scavenge for sweet and protein-rich foods.
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.
- Call Placer Mosquito and Vector Control District to report a yellowjacket nest:
The easiest to use are lure traps, which are available for purchase at many retail stores that sell pest control supplies. Lure traps can help reduce the number of localized foraging workers, but they don’t eliminate large populations. Lure traps contain a chemical that attracts yellowjackets into the traps, but the common lure in traps, heptyl butyrate, attracts primarily the western yellowjacket and not other species. Meat such as chicken can be added as an attractant and is believed to improve catches of the German yellowjacket and V. vulgaris. Replace meat frequently, because yellowjackets aren’t attracted to rotting meat. Also, periodically check the trap to remove trapped yellowjackets and make sure workers are still attracted to the trap. Lures need to be replaced periodically; follow trap directions regarding replacement.
To reduce the number of yellowjackets foraging in specific areas such as patios, picnic tables, concession stands, and Dumpsters, place lure traps with hepytl butyrate around the periphery. In large areas such as parks, place traps about 200 feet from the area to be protected and about every 150 feet along the circumference. In backyards, place them along the edge of the property line as far away from the patio or other protected area as possible. To intercept foraging yellowjackets, it is important to place the traps between the area to be protected and the native landscapes serving as nesting sites. Typically, yellowjackets will forage about 1/4 mile.*
Water traps generally are homemade and consist of a 5-gallon bucket, string, and protein bait such as turkey, ham, fish, or liver. Fill the bucket with soapy water and suspend the protein bait 1 to 2 inches above the water. A wide mesh screen over the bucket will help prevent other animals from reaching and consuming the bait. After the yellowjacket removes the protein, the yellowjacket flies down and becomes trapped in the water and drowns. Like the lure trap, these traps also work best as queen traps in late winter to early spring. In summer and fall they might assist in reducing localized foraging workers but usually not to acceptable levels. Place water traps away from patio or picnic areas, so wasps aren’t attracted to your food as well.*
* Courtesy of UNIVERSITY OF CALIFORNIA AGRICULTURE AND NATURAL RESOURCES Statewide Integrated Pest Management Program.
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 swelling 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 approved materials.
For more information, click here to download our brochure about yellowjackets.