By this time in August every year, underground yellowjacket nests have developed into large colonies, ready to swarm and sting the unsuspecting multiple times. Many people inadvertently find them while mowing the lawn, since running a lawnmower over their inconspicuous holes in the ground, will stir-up the entire nest. Their common name comes from the yellow and black stripes across their abdomens.
“While yellowjackets typically excavate nests underground (although they sometimes nest in above-ground structures such as in the cracks of stone walls that resemble underground habitats). Social wasps can be aggressive when defending their nest and females can deliver repeated stings when threatened. This is in contrast with honey bees, who sacrifice their life with just one sting. There are nine species of ground-nesting yellowjackets reported in Pennsylvania, occasionally these nests can grow to thousands of individuals.” Source
Since something like 5-percent of the population are hypersensitive to bee stings, many individuals maintain ready access to an EpiPen for an emergency treatment, as well as keeping 911 on speed dial (EpiPen is a disposable, single-use, auto-injector device containing epinephrine, a chemical that narrows blood vessels and opens airways in the lungs). Benadryl is often kept on hand to minimize an allergic reaction. Be sure to read and follow label directions for the use of any product.
Yellowjackets are actually considered beneficial insects in the home landscape, serving as pollinators and destroying many insect pests. The best way to locate an underground nest is through observation on a sunny day, where their nest will look like a bee airport, with multiple take-offs and landings.
We’ve heard some wild and dangerous stories about people illegally dumping gasoline down these holes and then lighting them on fire, often causing dangerous situations (like burning down their house) but it’s actually the fumes that kill the yellowjackets more than the fire. It would make far more sense to use one of the wasp and hornet aerosol sprays on the market that is labelled for this sort of use, or call in a professional exterminator. Some sprays may damage plant foliage.
Other recommendations we’ve seen: