Lawn & Garden
AUBURN UNIVERSITY, Ala. – “They’re heeere.” No, not a poltergeist. Yellow jackets are here.
As the summer ends and fall starts to make itself known, yellow jacket colonies are at their largest and most aggressive. While they are not coming out of a television set, these stinging pests can bring terror to yards and other outdoor areas.
Xing Ping Hu, an Alabama Cooperative Extension System entomologist, said it is important to be aware of the potential risk this time of year.
“They will attack if their nests are disturbed while mowing the grass or walking on your lawn,” Hu said. “A swarm of hundreds of yellow jackets can be extremely dangerous for people to encounter.”
What makes them so dangerous?
Yellow jackets are so named because of their bright yellow and black stripes. While often confused for bees, yellow jackets are actually an aggressive form of wasp. While people all react differently, yellow jacket stings have the potential to trigger a dangerous allergic reaction.
Hu said they will attack anything that they perceive as a threat to the colony.
“Sometimes, they sting you for no obvious reason,” Hu said. “Even if you are minding your own business and nowhere near a nest, they will sting you if their nest is disturbed or they feel threatened.”
This over-sensitive territorial nature is not the only thing that makes yellow jackets dangerous. When they attack, they will often bite to ensure that they have a firm grip. Also, unlike honeybees, yellow jackets do not lose their stinger after the initial sting. This means they can sting someone and keep coming back for more.
“When a yellow jacket stings, it tags the victim with an alarm pheromone that may last for hours,” she said. “This pheromone makes the victim a potential target for other yellow jackets. This is why even a single sting is dangerous.”
Looking for Nests
Yellow jackets can build their nests both above and below ground.
People can often find above-ground nests in cavernous areas such as attics, wall voids, crawlspaces and hollow logs.
Nests built below ground can be hard to locate, as the entrance is typically the size of a nickel. Yellow jackets will often build their nests in abandoned holes in litter-covered areas near bushes and shrubs.
“Look for small stones and dirt piling up around the opening of a burrow or hole,” Hu said. “These are signs of an underground yellow jacket nest.”
When looking for nests, it is best to search during the day when the worker wasps are entering and exiting the nest. Because these nests can be difficult to see, Hu recommends that people always take the proper safety precautions.
“When mowing or doing yard work, always wear protective clothes and shoes,” she said. “This includes gloves, a hat and possibly even a face mask or bee veil.”
There are a few preventative steps to take to keep yellow jackets from building nests. One option is to hang crumpled paper bags outside the doors and eaves of a house. These bags give the appearance of other nests, making the yellow jackets seek a different location.
Sealing up any awnings or cracks near the house is also a great preventative step. Because yellow jackets are scavengers, keeping garbage cans sealed and limiting other food resources for the workers will help keep them out of the area.
When it comes to treating yellow jacket nests, Hu said the job is best done at night.
“At night, the yellow jackets are drowsy and don’t see very well,” Hu said.
There are several chemical control options, but some are better than others. An insecticidal soap solution or dust product is great for controlling ground nests. Aerosol sprays for wasps and hornets have a limited effect and are not meant for treating an entire yellow jacket colony.
“For large colonies, call a licensed commercial pest control company to take care of the problem,” Hu said. “These professionals have access to specialized equipment and follow stringent safety protocols.”
Steps for Treating Underground Nests
- Locate the entrance to the nest.
- Pour the control product into the nest.
- Cover the nest opening with a glass pan to trap the yellow jackets inside until they die.
- Do not return to the area for at least 24 hours.
- Treatment may need to be repeated until there is no visible wasp activity.
The Alabama Extension content piece Lookout for Yellow Jackets – Outdoor Stinging Insects provides more in-depth information on yellow jackets. For further information, visit www.aces.edu or contact the home grounds, gardens and home pests regional agent serving your area.