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Identifying and dealing with yellowjackets

Our Master Gardener Help Desks routinely get calls or emails about bees, wasps, hornets, and other striped or stinging things. Often, residents need assistance to identify which insect they are dealing with, one of which may be yellowjackets, which are common in Illinois and often very active this time of year. With the great help of my colleague and fellow Extension Educator Chris Enroth, we’ve answered some FAQs about yellowjackets.

What are some of the differences between bees and yellowjackets?

Common Yellowjacket (Vespula vulgaris) can be mistaken for honeybees because both are about 1/2-inch long, have alternating bands of markings, and live in social colonies with a single queen. However, yellowjacket markings have distinct bright yellow and black, and a honeybee’s colors are a dull yellow-orange. Honeybees also are covered in small hairs, while yellowjackets are mostly hairless.

Why and when do yellowjackets attack?

We may get more Master Gardener Help Desk calls about wasps this time of year because there seem to be more “attacks” in August and September. According to Chris, “Late in the season, yellowjackets will begin to aggressively pursue food. As flowers fade in the late summer into fall, nectar sources dwindle, making food scarce for the colony. Uncovered trashcans, picnic-goers, and concession stands are all fair game and is where most encounter yellowjackets.”

“By late summer the population of yellowjackets in the nest is at its maximum, offering many troops to help defend the colony. Perhaps the most dreadful of tactics, the yellowjacket can sting multiple times. Unlike bees, a hornet’s stinger does not have a barb that lodges into its victim. A yellowjacket's stinger is smooth and can be used repeatedly, injecting a dose of venom each time. An attacking or smashed yellowjacket also gives off a chemical signal to fellow nest-mates drawing them to battle. This is why you should never swat a yellowjacket. Instead, wait for the yellowjacket to depart. Often, they are simply investigating you and will leave momentarily. If you cannot wait, push them off with a piece of paper, or slow deliberate motions. Avoid flailing your arms and hitting them, as you will then be perceived as a threat.”

According to Chris, “yellowjackets often will not sting a person unless the nest is agitated. If a yellowjacket colony is identified near a home or where it may come in contact with people, make sure to keep children out of that part of the yard and warn adults and neighbors.”

How do you manage yellowjackets?

Chris warns that controlling a yellowjacket colony brings its own share of risk. (His past blog "Dealing with Yellowjacket Wasps" provides helpful methods and tips for controlling exposed, ground, and concealed nests.) If you are allergic or you are not comfortable eliminating a yellowjacket nest, hire a professional.

Sometimes, residents do not have a yellowjacket nest in their yard, but their gardens are frequented by foragers. Make sure to the garbage can lids are on tight and food is cleaned up to keep roving yellowjackets away from people places in the yard. Traps also can be set up to draw them away from family gathering areas or if you are hosting an event. Traps can be purchased from a variety of stores and should be put out 2 to 3 days ahead of an event. (Always read and follow label instructions).

About the author: Richard Hentschel’s expertise extends across several subject areas with specialties in lawn care, fruit tree production, woody ornamentals, and home and community gardening. During his 45-year career in horticulture and agriculture, Hentschel became a well-known and respected expert for commercial and homeowner audiences, industry organizations, and media. He retired from University of Illinois Extension in April 2022 with nearly 30 years of service as a Horticulture Specialist and Educator in northern Illinois.