Don't Throw Out Those Coffee Grounds! Use Them As A Natural Mosquito Repellent Instead

There's nothing like a summer morning in the backyard, sipping a cup of coffee and enjoying the sunshine. That peace gets punctured quickly when mosquitoes arrive, though. We fight against these little nuisances all summer long with everything from wearable bug repellents to citronella incense sticks and candles. There's no shame in using more than one mosquito repellent to keep the bugs at bay, and you might want to use the grounds from that morning cup of coffee.

Some say you can repel mosquitoes if you burn coffee grounds nearby, spray brewed coffee directly on your skin, or toss coffee grounds in the garden. We wanted to know all the ways coffee grounds can repel mosquitoes (plus, does it really work?), so we turned to an expert: Emma Grace Crumbley, entomologist at Mosquito Squad, a pest control company operating in 39 states across America. Crumbley pointed to two studies that show coffee can repel mosquitoes and kill their larvae, a 2012 study published in the Frontiers of Physiology journal and a 2015 study by the National Center for Biotechnology Information (NCBI). But the EPA doesn't recognize coffee as an insecticide or repellent. Crumbley said, like other natural pest control methods, it might be effective, but "this is not a one-and-done solution."

"Pest control is complex and often requires addressing multiple issues to target, remove, and prevent pests. While coffee may discourage mosquitoes and pests from your yard, it should not be relied on as a long-term solution," Crumbley said.

If you want to create a mosquito-free backyard, it might take a little more than just a sprinkling of coffee grounds or a few citrus peels. But, you can enhance all other pest control measures you're taking by adding coffee grounds to the procedure. And if you bury them in the garden, you'll have them pulling double duty as both pest control and plant food. "Since coffee grounds are nitrogen-rich, this method would work best for home gardens, where even if pests aren't discouraged by the coffee, the grounds can help enrich the soil and provide plants with the nutrients they crave," Emma Grace Crumbley said.

Burning coffee grounds might be a more potent insect repellent because of the intense smell of their smoke. Plus, the burnt grounds will continue to deter some pests after the fire goes out. Crumbley suggested: "Place burnt grounds near doorways, windowsills, and around the perimeter of the house to help discourage pests from trying to come inside."

Combine coffee grounds with other natural insect repellent measures, like planting a garden with mosquito-deterring herbs like lemongrass. Another way to help lower the mosquito population in your backyard is to create an environment that welcomes mosquito-eaters like bats, birds, and frogs. "Natural repellents can be cheaper, especially if you use essential oils, plants, or coffee that you already have around your home," Crumbley said. "Still, any DIY treatment should be paired with integrated pest management techniques."