Wasps are generally harmless. Of the approximately 18,000 species in North America, only a few pose a risk to humans. The rest help control insect populations such as aphids and spiders, and are also important pollinators that help our gardens, crops, and wildernesses thrive. So just because you see a wasp doesn’t necessarily mean you should reach for the spray can.
“If the nest is on your property, but in a low-traffic area, you may want to consider leaving it alone,” says Rocky Beninato, a certified pest control professional and founder of Quality Affordable Pest Control. “However, if you or your family are allergic to wasp stings, you should remove them regardless of location.”
If you have a wasp nest that is too close, read here how to remove it safely while still being considerate of the surrounding area.
When is the best time to spray a wasp nest?
Wasps are usually out foraging when it is warm, so it is best to spray nests during cooler times, such as early morning, late evening, and when the weather drops below 50 degrees. They are more lethargic and will congregate in their nests at that time.
Start by looking for nests built in early spring, when they’re no bigger than a golf ball, says Tom Dobrinska, an entomologist with Terminix. “Early spring, there are fewer wasps and they’re easier to treat quickly,” he says.
How does wasp spray work?
Wasp sprays are aerosol insecticides, usually containing chemicals such as pyrethrin or pyrethroid, which disrupt the insect’s nervous system on contact. Most are designed to have a long range, so they can be applied from a distance.
“The key is direct contact with flying adult wasps,” says Emma Grace Crumbley, an entomologist at Mosquito Squad. Otherwise, spraying the outside of a nest won’t necessarily kill the larvae, pupae and adult wasps inside.
How to spray a wasp nest
First, try to figure out what type of wasp you’re dealing with, says Crumbley. The spray is most effective on visible above-ground nests, such as those of common wasps, hornets and dirt wasps. But it may not be as effective on ground-dwelling wasps like yellow jackets, velvet ants and digger wasps. Next:
- Wear personal protective equipment (PPE) to protect yourself from stings, such as a bee suit or thick clothing with long sleeves, safety glasses, gloves, a protective hat, and closed shoes. Keep first aid equipment on hand, such as an epinephrine auto-injector (EpiPen), bandages, anesthetic wipes, and hydrocortisone cream. Never spray when the wind is blowing.
- Cover the area below with a ground sheet to protect it from the spray.
- Read and follow the instructions on the label so you’re aware of important factors like the size of the can and whether you need to shake it first.
- Spray the nest thoroughly, aiming the wasp spray at the opening. “As wasps fall out, spray as much wasp spray as possible,” says Crumbley. “After you’ve dealt with the entrance and any nearby wasps, spray the nest thoroughly with the product.”
- Leave the nest alone for the next day or two, following the directions on the product label.
- Check for wasp activity. If there are still live wasps, repeat the above steps.
How to Safely Remove a Wasp Nest After Spraying
First, check the instructions on the can and put your PPE back on. Then, use a broom handle to remove the nest and put it in a garbage bag, Beninato says. Tie the bag shut, put it in an outside trash can, and then use soap and water or diluted bleach to clean the area where the nest was.
When to Call a Professional
Because wasps can be aggressive, many people choose to call in a professional, especially if:
- They are allergic to wasps, or don’t know because they have never been stung.
- The nest is difficult to reach or is close to water or electrical outlets.
- It is a particularly aggressive species, like the wasps, the bald hornet, the Asian giant hornet and the warrior wasps.
- It is a large nest or a nest hidden in the walls of your house.
How do you prevent wasp nests?
Of course, prevention is the best solution to living in harmony with wasps, according to the Butterfly Pavilion entomology department. They suggest:
- Empty and clean outdoor trash bins regularly, put lids on them, and place them in a place where you don’t need to keep them at home.
- Check for new nests by inspecting overhangs and hollow posts.
- New nests are removed in the evening with a strong jet of water. The area is then repeatedly cleaned with peppermint oil.
- Creating natural food areas, small habitats and placing flowering plants at least 15cm away from busy areas so that people are less concerned about stings.
Dobrinska also recommends fixing screens, keeping pet food inside, and using high-powered fans to keep wasps at bay when people are eating on the porch. In late summer, you can also try putting sugar water in a corner of the yard to lure them away from the dining area.
Frequently Asked Questions
When do wasps disappear?
Wasps become scarcer in the fall and are usually gone by the beginning of winter. “As temperatures cool and resources become scarce, wasp queens lay fewer eggs and wasp populations begin to decline,” Crumbley says. They never really disappear, though, because queens find a safe place to hibernate, return and build a new nest in the spring, Dobrinska says.
How fast do wasps fly?
The exact speed of wasp species has yet to be clearly defined, Crumbley says. “Some sources say wasps can fly as fast as 7 mph, 15 mph or 25 mph, depending on the species,” she says. “Regardless of their exact speed, wasps fly fast and are hard to outrun.”
Can vinegar kill wasps?
Yes, because it can clog the air holes along the insect’s body that they use to breathe. But it’s not a good solution, says Crumbley. “I caution readers not to fall for these pest control gimmicks,” she says. “These products are not knockdown agents and would only kill the wasps if they were immersed in the product.”
Beninato agrees. “Vinegar might kill wasps if you drown them in it, but it probably won’t work very well,” he says. “The wasps would most likely fly toward you and sting you.”
However, the smell of vinegar can be a deterrent to wasps, and it is also useful to use it when cleaning the area where you removed the nest, so that the wasps do not return.
Does gasoline kill wasps?
Yes, but again, it’s best not to try this hack, says Crumbley. Viral videos show people holding a cup full of gasoline near the entrance to a wasp nest and the wasps falling in and dying. “Open cans of gasoline are dangerous enough, but if you miss the nest opening, remove the cup too early, and have last-minute nerves, irritated wasps can sting and gas can leak everywhere,” she says.
About the experts
- Tom Dobrinska is a Certified Entomologist and Technical Service Manager for Terminix. During his 30+ years in the pest control industry, he has held positions including Pest Technician, Operations Management, and Training and Development.
- Emma Grace Crumbley is an entomologist at Mosquito Squad and calls herself an insect nerd. She uses her expertise to educate people about the fascinating world of insects.
- Rocky Beninato is a certified pest control professional and founder of Quality Affordable Pest Control, an eco-friendly and pet-friendly pest control company based in Toronto.
Sources
Butterfly Pavilion in Westminster, Colorado, is the world’s first AZA-accredited, free-standing, nonprofit invertebrate zoo.