The Coffee Grounds Hack People Use To Deter Wasps (& Is It Really Effective)

When you're sitting outside trying to enjoy a cool drink or work in your garden, having pesky wasps buzzing around can be nerve wracking. If you're not keen on using pesticides, you may be looking for a way to help naturally repel wasps, and some say that coffee grounds are the solution. Pest control companies as well as gardeners and redditors have stated that burning coffee grounds outside will help to deter wasps from your space. The theory is that the smell of the smoke, as well as some of the components of the coffee itself, will drive off wasps as well as some other insects.

Though some people believe that you should look into keeping a jar of coffee grounds on your patio to keep these stinging insects at bay, there seems to be limited research on how the smoke from coffee grounds affects wasps specifically. The research may not have been done yet, but there's still a chance this method has some basis and could be an interesting experiment, as other studies have shown coffee can be an insect repellent. 

Despite a lack of focused research, some pest experts support the idea that burning coffee can deter a variety of insects, including wasps. While the powerful scent of burning coffee is what's often thought to drive pests away, the chemicals inside the coffee may also have an effect on insects. Guy Halverson, who works with the Truly Nolen pest company, explained to Homes & Gardens why burning coffee can keep pests away while you're enjoying your outdoor space. "Coffee grounds contain compounds such as caffeine and diterpenes, which can act as a natural insecticide. They have a strong scent but become even more potent when burned," he said.

Additionally, a 2015 study published in Parasites & Vectors found that coffee grounds could deter female aedes albopictus mosquitoes and negatively affected the larvae as well, showing that some flying insects are repelled by coffee. While using smoke to bring wasps out of their nest before removing it probably isn't a great idea, it may be able to keep them from bothering you while you're outside; however, it likely is not a permanent solution for dealing with these stinging insects and there's no guarantee it will be as effective as is claimed.

First, you'll want to find a container that's suitable to hold burning material, such as aluminum foil, a disposable pie tin, or a metal can. Start to save your used coffee grounds and leave them out to dry. While you can use fresh coffee grounds, used ones should work the same and would be the more economical choice. Place your dried grounds into your container, bring it outside, and ignite it. Depending on what you put your coffee in, you may want to place a hot pad or coaster underneath to ensure the heat doesn't damage anything.

You can set your wasp repellent on your patio table, or you might place it upwind of wherever you'll be spending your time. Make sure that you put the fire out before going inside and replace your coffee grounds every so often to ensure the smell doesn't dissipate. With just some coffee grounds, you may be able to ward off pesky wasps, but know that it's not a foolproof method and you might still see these insects around your yard.