When Is the Best Time to Spray a Wasp Nest?

Wasps are, for the most part, harmless. Of the 18,000 or so species in North America, only a few present a risk to humans. The rest help keep insect populations like aphids and spiders in check, plus are important pollinators, helping our gardens, crops and wildlands flourish. So, just because you see a wasp, doesn’t necessarily mean you have to reach for the spray can.

“If the nest is on your property but in an area with low traffic, you can consider leaving it alone,” says Rocky Beninato, a certified exterminator and founder of Quality Affordable Pest Control. “However, if you or your family are allergic to wasp stings, you should remove them regardless of the location.”

If you have a wasp nest that’s too close for comfort, here is how to safely remove it, while still being sensitive to the environment.

When Is the Best Time to Spray a Wasp Nest?

Wasps are usually out foraging for food when it’s warm, so it’s best to spray nests at cooler times, like early morning, late evening and when the weather dips below 50 degrees. Then, they will be more lethargic and gathered in their nests.

Start looking for nests being built in early spring, when they’re no bigger than a golf ball, says Tom Dobrinska, an entomologist with Terminix. “Early small nests have fewer wasps and are easier to treat quickly,” he says.

How Does Wasp Spray Work?

Wasp sprays are aerosol insecticides, which typically contain chemicals such as pyrethrin or pyrethroid that disrupt the insect’s nervous system upon contact. Most are designed to have a long reach, 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 species of wasp you’re dealing with, says Crumbley. The spray is most effective on visible above-ground nests, like those made by common wasps, common hornets and dirt daubers. But, it may not be as effective for ground-dwellers like yellow jackets, velvet ants and digger wasps. Next:

• Put on personal protective equipment (PPE) to protect you from stings, including a bee suit or thick long-sleeved clothing, eyewear, gloves, protective headgear and close-toed shoes. Keep emergency first-aid gear ready, including an epinephrine auto-injector (EpiPen), bandages, anesthetic wipes and hydrocortisone cream. Never spray when it’s windy.
• Cover the area below with a ground tarp to protect it from the spray.
• Read and follow the instructions on the label so you know important factors like the reach of the can and whether you should shake it first.
• Spray the nest thoroughly, aiming at the opening. “As wasps spill out, spray as many as possible with the wasp spray,” says Crumbley. “After targeting the entrance and any wasps nearby, your goal should be to thoroughly douse the nest with the product.”
• Leave the nest alone for the next day or two, according to 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 spray can instructions and put back on your PPE. Then use a broom handle to remove the nest and put it into a garbage bag, says Beninato. Tie the bag, place it in an outdoor trash can, then use soap and water or diluted bleach to clean the area where the nest was.

When to Call a Pro

Because wasps can be aggressive, many people choose to call a professional, especially if:

• They’re allergic to wasps, or don’t know if they are because they’ve never been stung.
• The nest is difficult to access or close to water or electrical outlets.
• It’s a particularly aggressive species, like yellow jackets, bald-faced hornets, giant Asian hornets and warrior wasps.
• It’s a large nest, or one hidden in the walls of your home.

How to Prevent Wasp Nests

Of course, prevention is the best solution for living in harmony with wasps, according to Butterfly Pavilion‘s entomology department. They suggest:

• Empty and clean outdoor garbage cans regularly, cover them with a lid and store them away from the house.
• Monitoring for new nests by inspecting overhangs and hollow posts.
• Knocking down new nests using a strong water stream at dark, then repeatedly cleaning the area with peppermint oil.
• Creating natural feeding areas, pocket habitats, and putting all flowering plants at least six inches from heavily trafficked areas to ease human concern about stung.

Dobrinska also recommends repairing screens, keeping pet foods inside and using strong fans to keep wasps at bay when people are dining on the porch. During late summer, you can also try placing sugar water in a corner of the yard to lure them away from the eating area.

FAQ

When do wasps go away?

Wasps become more scarce in the fall and are usually gone by early winter. “When temperatures cool and resources thin out, wasp queens will lay fewer eggs, and wasp populations will begin to drop off,” says Crumbley. However, they never really go away since queens will find a safe place to overwinter, come back, and establish a new nest in the spring, says Dobrinska.

How fast do wasps fly?

The exact speed across wasp species has yet to be clearly recorded, says Crumbley. “Some sources say wasps can fly as fast as 7mph, 15mph or 25mph, depending on the species,” she says. “Regardless of their exact speed, wasps fly fast and are difficult to run away from.”

Will vinegar kill wasps?

Yes, because it can clog the spiracles along the insect’s body that they used to breathe. But it’s not a good solution, says Crumbley. “I caution readers not to fall for these pest control hacks,” she says. “Those products are not knockdown agents and would only kill the wasps when submerged in the product.”

Beninato agrees. “Vinegar could kill wasps if you drowned them in it, but this is unlikely to work well,” he says. “The wasps would most likely fly towards you and sting.”

However, the scent of vinegar can be a deterrent to wasps, and it is helpful to use for cleaning the area where you’ve removed a nest to discourage them from returning.

Does gasoline kill wasps?

Yes, but again, it’s better not to try this hack, says Crumbley. Viral videos show people holding a cup filled with gasoline around the entrance of a wasp nest and the wasps falling in and dying. “Open containers of gasoline are dangerous enough, but missing the nest opening, removing the cup too soon and last-minute nerves can cause aggravated wasps to begin stinging and gas to spill everywhere,” she says.

About the Experts

• Tom Dobrinska is a board certified entomologist and Technical Service Manager for Terminix. During his 30-plus years in the pest control industry, he has worked in roles including pest technician, operations management and training and development.
• Emma Grace Crumbley is an entomologist at Mosquito Squad and a self-described bug nerd who uses her expertise to educate people about the fascinating world of bugs.
• Rocky Beninato is a certified exterminator and founder of Quality Affordable Pest Control, an eco-friendly and pet-safe pest control company based in Toronto.

Sources

Butterfly Pavilion, in Westminster, Colorado, is the first AZA-accredited, stand-alone, non-profit invertebrate zoo in the world.