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Yellowjackets - Biology

MORE about yellowjackets and their behavior

What Is a Yellowjacket?

 yellowjacket image

Yellowjackets, sometimes known as hornets, are wasps that are black and yellow or white.(2)

Common pest species in the Northwest are the western yellowjacket, the common yellowjacket, and the German yellowjacket.(3)

A wasp that is commonly mistaken for a yellowjacket is the paper wasp. They are longer and more slender than yellowjackets(3) and are usually unaggressive.(4) Their nests are a single comb, and not surrounded by a paper envelope.(3)

yellowjacket nest

Yellowjacket Nests
All yellowjackets build paper nests that are completely surrounded by a paper envelope. Most yellowjackets nest underground. They often use burrows made by rodents or other natural openings as nest sites. The German yellowjacket likes to nest inside walls of houses. There are two kinds of yellowjackets, the aerial yellowjacket and the bald-faced hornet, that hang their nests from trees or building eaves.(1)

Most yellowjackets defend their nest vigorously, and being near a nest means you’re likely to get stung.(2,3)  Typically, the ground-dwelling yellowjackets are the most aggressive, while those that nest above ground are somewhat less touchy.(3)

Seasonal Behavior
Most yellowjackets die with the first frost in the fall. The nest is abandoned and typically not used again. Only the queens find a protected spot to spend the winter. In the spring, the queens build new nests and begin laying eggs which hatch into worker wasps. All summer the number of workers increases. By the end of summer there can be thousands of yellowjackets in a nest. This is typically when the yellowjackets are most troublesome.(1)


1. Landolt, P.J. and A.L. Antonelli. 2003. Yellowjackets and paper wasps. Washington State Univ. Cooperative Extension Publ. EB0643.
2. Univ. of California. Agriculture and Natural Resources. 2001. Yellowjackets and other social wasps. Pest Notes Publ 7450.
3. Oregon State Univ. Extension Service. 1995-2006. Garden hints: Life’s a picnic for yellow jackets this time of year.


U.S. EPA. Office of Pesticide Programs, Undated. IPM for schools: A How-to manual. Chapter 19.  IPM for yellowjackets and hornets in schools.

Sacramento-Yolo Mosquito and Vector Control District. Undated. Vector information. Information about vectors: Mosquitoes, yellowjackets, wasps, bees, spiders, rats, etc. Frequently asked questions about yellowjackets.

Wegner, Gerry. 2003. Yellowjacket IPM: A baiting and trapping strategy works, if you time it right.

Sugden, E.A. Undated. Managing yellow jackets in the Puget Sound region.


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