Few pest infestations are more frightening than an invasion of wasps — and for good reason. Venomous, territorial and aggressive, wasps are not to be taken lightly. There are right ways and wrong ways to deal with them, and wasps are not the type of pest that leaves room for strategies based on trial and error. People typically can deal with most wasp infestations on their own. Some of the more aggressive species and less-accessible infestations, however, should be handled only by professionals.
First, Know What You’re Dealing With
Some people lump common honeybees and wasps together in their minds. They are related and they display similar behaviors, but they are two very different creatures, and a wasp infestation is far more dangerous than the arrival of unwelcome honeybees.
Although wasp colonies are generally much smaller than those of honeybees—ranging from just a few wasps to 5,000 or more in a single colony, compared with more than 50,000 for bees—individual wasps are much bigger than bees. They’re more aggressive and, unlike common bees that die after a single sting, wasps can sting multiple times in sustained attacks.
There are more than 100,000 species of wasps. Some don’t sting at all, and some are solitary insects. But many species, like yellow jackets and hornets, are known to launch unrelenting attacks in massive swarms when they feel threatened. With species that rank among the most dangerous insects in the US, the worst wasp attacks can be fatal to animals and humans.
Tip: Don’t swat a wasp outside! During an attack, some wasps emit a chemical pheromone that acts as a call to war for others in the nest. Even if you succeed in killing a lone wasp, you could trigger a much larger attack. Swatting also is a bad idea in the home because a miss is likely to make the insect aggressive. Instead, purchase a chemical spray.
Wasp or Bee?
Unlike their smaller, hair-covered honeybee relatives, wasps generally are larger and have smooth bodies, which are sometimes covered in stripes or bright yellow or orange markings. They have four wings, and their defining characteristics are very narrow waists and long, dangling legs. Yellow jackets are common across the entire eastern US, particularly the Southeast. They often are mistaken for bees because their yellow-and-black bodies look similar, but they are faster, they often fly side to side, and they are much more aggressive than bees.
Hornets are much larger than bees, yellow jackets and most other wasps, sometimes growing as long as two inches. They also are commonly found throughout the eastern US.
Unlike honeybees that create hives in chambers such as hollowed-out logs, many wasps build nests, and these nests can remain hidden under eaves or in wall hollows.
Spotting the Nest
If you think you have a wasp problem, the goal is to find and destroy the nest.
Yellow jackets create nests underground that sometimes are discovered accidentally — and often painfully — while a person is mowing or gardening.
Hornet nests, which are by far the most difficult and dangerous to deal with, look like mushy gray or grayish-brown footballs and usually are found attached to trees or the sides of homes.
If you think you’ve spotted a hornets’ nest, your best bet is to call a pest professional right away because these nests are notoriously durable and difficult to penetrate and destroy.
Common paper wasps build nests that look like upside-down umbrellas. They usually are found in the open, along rooflines or under eaves.
European hornets build nests that are covered in a papery material. They can be found both indoors and out, in attics, inside walls, on trees, on the sides of buildings or in bushes.
Mud wasps build relatively small nests in existing masonry cracks…or sometimes in attics or under decks.
Helpful hint: No matter what kind of wasp you are dealing with, your strategy for locating the nest (if the location isn’t obvious) is the same. When you see a wasp, observe it from a safe distance and watch where it goes. If it enters a hole or gap in your home, that likely is the entrance to the nesting site.
Using Chemical Treatments
If you decide to treat the nest on your own, which some people do to save money or simply because they are DIYers at heart, it should be attempted only where nests are visible and accessible. If you suspect wasps are hidden within walls or other concealed places, professional services are recommended.
You can use one of the commonly available chemical spray treatments sold under brand names such as Black Flag, Spectracide and Repel. Make sure that you buy a spray designed specifically for wasps, including hornets and yellow jackets. The chemicals in these sprays have been specifically designed and tested to destroy these insects.
Practice with a brief test spray away from the nest outdoors. Then plan a short escape route indoors, aim at the nest, spray until you have covered the nest and retreat inside. Monitor the nest for activity, and repeat as needed throughout the day.
Caution! Never attempt to treat a nest if a ladder or any sort of climbing is required. A single sting could trigger a fall, leaving you injured and unable to retreat from the rest of the swarm.
Spray with the wind at your back, and wear protective eyewear along with long clothing to protect against both chemical contact and stings.
Pro tip: Never place yourself between the sun and a wasp nest. Wasps react to shadows and often become agitated and aggressive when shadows move over their nests. They are known to attack the source of the shadow by flying toward the sun.
Treat Wasp Nests at Night
If you decide to treat a wasp nest yourself, it is better to wait until after dark for two reasons. First, the wasps won’t have the sun to orient themselves for an attack. Second, all the wasps are back in the nest and accounted for at night.
Remember: Don’t use a flashlight! The light is likely to agitate the wasps and give them a focal point for attack.
Some people want to avoid using chemicals because they prefer more natural remedies for infestations. They can try treating nests with soap and water, which can suffocate the wasps and kill them.
Be careful! Unlike chemical spray treatments that knock wasps down immediately, soap and water may have a delayed effect. There is no set soap-to-water ratio, but the water should be visibly soapy. Commercially purchased wasp sprays come in aerosol cans that can spray more than 20 feet, a distance you should try to match or beat with your delivery method. A common spray bottle will force you to get too close. Products such as Ladder Saver and Little Big Shot are extension nozzles that expand the reach of garden hoses by dozens of feet, and these may be adequate to accurately hit a wasp nest with soapy water from a safe distance. While soap and water has been proven to kill wasps, it is important to note that chemical sprays are likely to achieve the best and safest results.
Finish the Job
No matter the treatment, destroy the nest after killing the wasps. When a treatment kills all the workers, pupae remain in the nest. If the nest is not dismantled and destroyed, those pupae could hatch and become active. Once you are certain that there is no more activity — after multiple sprays, if necessary — use a long-handled tool such as a rake or shovel to knock down the nest. If you are certain that there is no longer any activity in or around the nest, it is OK to climb a ladder to carefully remove it. Wear protective gloves…and break the nest apart and saturate it with more spray before disposing of it in the trash or as yard waste.