By Jeff Burbrink
Ag & Natural Resources Extension Educator, Purdue Extension LaGrange County
LAGRANGE — While enjoying the beautiful weather this weekend, I stumbled onto an underground yellow jacket nest. The unhappy residents of the nest managed to sting me only once, but that single pop to the back of my head had me seeing stars for a while.
Late summer is when most people have their encounters with yellow jackets. They are busy finding carbohydrates to help their colony, specifically their queen, prepare for the winter. Having a picnic, or leaving a garbage can uncovered is an invitation to the hungry little critters.
We have several species of yellow jackets in northern Indiana. Some species prefer to nest in the ground, while others nest in hollow cavities, like trees, cracks in landscape timbers, or the walls of your home. Caution should be taken around yellow jackets, especially if you find a nest in an area where you spend a lot of time. People frequently mistake yellow jackets for bees, but bees do not usually exhibit these nesting behaviors.
The underground nests are particularly evil in my opinion. This time of the year, the nest may be as big as a basketball in a hollowed-out space hidden just under the turf. The paper nest cannot support much weight, so unsuspecting people, animals, or lawn mower drivers can easily find themselves calf-deep in a stinging frenzy.
Workers vigorously defend the nest and queen. Their sting is more painful than a honey bee and normally no stinger remains in the skin. Unlike a bee, a single yellow jacket can sting more than once.
A queen is the soul of each nest and her sole responsibility is to lay eggs. She begins a nest in the spring by laying a few eggs and raising the adults. Workers search for food, expand and defend the nest. As spring and summer pass, the nest grows and new workers assume their role. By the end of summer, nests may contain a thousand workers. By August or September, their population is at its highest.
By fall, yellow jacket nests have produced a crop of new queens and males. By the first frost, the queens leave the nest to find a protected spot to spend the winter. They emerge in spring to begin the cycle again. Only new queens survive the winter, however, and they rarely reuse the previous year’s nest.
For control, you must first locate the nest entrance. Wear long sleeves and pants that covers your skin, and carefully mark the nest entrance. This will help you to find and treat the nest on a cool night, when workers are inside and relatively calm. Use an insecticide that is labeled for yellow jacket control, and follow all directions for use. A quick-acting, knockdown pesticide should be used, to keep yellow jackets from flying out of the nest.
Don’t pour petroleum products into ground nests. It is dangerous, environmentally harmful, and illegal. Use products specifically made for yellow jacket control only. Be sure to read and follow the pesticide product label. Remember, the label is the law.
Non-toxic yellow jacket traps are available in yard and garden stores. They use a synthetic attractant to lure worker yellow jackets into the trap. Traps may provide temporary relief by drawing workers away from people, but they are not effective for area-wide nest control.
Yellow jackets nesting in the wall of a home are much trickier to control. Do not plug the exit hole. They will find an alternative exit, and 50% of the time, they wind up inside your home. It is best to leave this issue to the professionals.
I also have had calls about hornets’ nests, with large gray paper nests found hanging in trees. If the nest is out of the way, it is probably not going to interfere with your life at all. That said, if the hornets built the nest at ground level or on the side of a home, it might be wise to treat it with an aerosol insecticide designed to squirt 15-20 feet. Typically, twotreatments are needed to completely control the hornets.
For more information about social wasps, yellow jackets and hornets, visit extension.entm.purdue.edu/publications/E-44/E-44.pdf