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Over the Garden Fence

Yellow Jackets and Hornets

While there is a lot of summer left, now is the time homeowners are discovering nests of a variety of flying, swarming and potentially stinging wasps and hornets in the home landscaping. In nearly all cases, homeowners have been unaware that a nest even exists in the yard until one day when foliage starts to change color or the nest itself grows in size and becomes much more visible. The more common paper nest building wasp builds a flat nest under the eve of the home or near the gable on the end of the home. Another wasp that can easily be spotted by the nest it builds is the mud dauber. You will see singular or multiple rows where mud was used to build the rows of tunnels containing the eggs and food supply. The Bald Face Hornet builds a much more elaborate nest usually found in the canopy of a tree. Their nest resembles a mottled grey football. Once in a while a nest will be found attached to the home in an area seldom seen. Farther down on the ground, yellow jackets like to nest in abandoned rodent holes and runs in the soil besides building voids, cracks and crevices which can be commonly found on homes.

Yellow Jackets are the ones that bother us the most during outdoor events, as they like to snack on the same foods we do. Sweet pop is a favorite. One trick you might try is to actually feed them starting two or three days ahead of the event in an area well away from the picnic. They get used to finding an easy meal and it will take quite a while before zeroing in on the meal you have for the picnic goers. Yellow jackets can sting repeatedly. The next most likely to be ready to sting are the paper nest building wasps and hornets. They will leave you alone if you leave them alone, but will certainly sting if provoked. Any of these insects will protect themselves when threatened and do so in great numbers.

Wasps, Hornets and Yellow jackets start a new nest every year and are not necessarily going to nest in the same spot year after year, while if you have a great spot you can have repeat nest building. These insects will typically die off in the fall with enough overwintering adults to start again the following year. Adults overwinter singularly in cracks and crevices and in naturally occurring spots in nature.

Lessor known stinging insects include Carpenter bees (only the female when disturbed), found tunneling in wood and the Giant Cicada Killer that only really stings its prey.

When these stinging insects pose a real threat to humans, control measures are warranted. Treating a nest can be very dangerous, so be well prepared and have a buddy system in place! If you just have found the nest and have not been bothered all summer, let nature take its course. All of these stinging insects are important to the insect world, our ecosystem and our food chain. If you are finding stinging insects, check the condition of the caulking on the home. Those that have strong allergic reactions to a sting should talk with the family doctor about potential treatments.

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.