Does Coffee Really Repel Mosquitoes?

Author: Emma Grace Crumbley, Entomologist 

When mosquitoes take over our yards, we're all itching for new ways to prevent these blood-sucking pests! Recently, coffee grounds have become the next big thing in DIY mosquito control on Instagram Reels, YouTube Shorts, and TikTok. But does this hack actually work? Here's what we know:  

Coffee as a Repellent

When examined for repellency, coffee has been found to have some repellent and larvicidal properties. In a 2012 study published in Frontiers of Physiology, scientists found that brewed coffee diluted with water has larvicidal properties. Mosquito larvae could not survive in water bodies containing brewed coffee, and changing the pH and clarity of the water increased larvae mortality.

Research done in 2015 by the National Center for Biotechnology Information (NCBI) also supports the claim that coffee grounds can repel mosquitoes. In this study, scientists examined if female mosquitoes would lay their eggs in bodies of water with coffee. The results showed that female mosquitoes were repelled from these water sources.

Burning Grounds

So, brewed coffee seems to work pretty well. But what about just the grounds? Why waste a delicious cup of coffee on mosquitoes if the used, old grounds work?

Well, sprinkling coffee grounds may repel some insect pests, though you would need a lot of coffee to achieve full-yard coverage. 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.

Burnt coffee grounds have a more potent smell that repels insects. Although burning the grounds will rob them of their nutritional content and may not benefit your soil as much, this method should still repel mosquitoes from entering your home. Place burnt grounds near doorways, windowsills, and around the perimeter of the home to help discourage pests from trying to come inside.

Pros and Cons

To review, coffee has several pros and cons as a mosquito and pest repellent. Upsides to this method include:

• It's cheap! If you're already a coffee drinker, save those grounds instead of throwing them away. Less waste and more bang for your buck.
• You have options. Whether you use brewed coffee, used grounds, or burnt leftovers, the evidence suggests you should see results in your pest presence.
• Plants love coffee, too! The nitrogen in coffee grounds helps plants continue to thrive while discouraging pests from attacking your garden.

However, no method is perfect (I mean, if it was, everyone would be using it!). Downsides to using coffee include:

• Coffee is not EPA-registered. This may come as no surprise, but coffee and coffee grounds are not officially recognized or registered by the EPA for their insecticidal properties or repellency. In fact, coffee is not designed to be a pesticide at all. So, there is a good chance that the results will vary for this technique.
• This is not a one-and-done solution. It's important to keep in mind that 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.
• Burnt coffee can attract bears… so be aware of your region's wildlife before taking on this hack!

Final Thoughts

Several steps of mosquito and pest control can be DIY projects. Removing standing water, keeping a tidy yard, and adding screens to doors and porches all help reduce the number of pests living and breeding in and around your home. However, experimental "hacks" like this are not long-term solutions to pest problems. Coffee grounds are a home remedy that allows you to use your grounds past brewing instead of throwing them away. Still, any DIY treatment should be paired with integrated pest management techniques, such as the professional pest services Mosquito Squad offers.

But if you do try this method, let us know what you think! We love keeping up with new trends in pest control and would love to hear your feedback on the coffee hack. Send us a message on social media and follow us @mosquitosquadco.

Smell the Roses, Not the Mosquitoes!

Are you looking for a natural mosquito control option? Mosquito Squad has you covered. Call today to learn about our natural mosquito treatment option and get a free quote!