Do Coffee Grounds Actually Keep Ants Away From Your Kitchen?

The quadrillions of ants in the world (no, that's not an exaggeration) are critical components of their native ecosystems, but your kitchen cabinets don't have to be included in that category. Is there anything more gross and frustrating than seeing those industrious worker insects marching in formation across surfaces where you store or prepare food? Seeing as pesticides are inherently toxic, you may consider more natural remedies to rid your kitchen of these pests. Coffee grounds, for instance, are a popular folk remedy for deterring ants, and some folks claim that this breakfast castoff can actually kill them. A lot of people start their day with a hot cup of joe and, consequently, have a lot of otherwise useless coffee grounds. Seems like kismet!

While this "hack" for non-toxic pest control may be slightly more logical than trying to use your coffee grounds as instant coffee, coffee has limited usefulness in the fight against ants. A 2018 study published in the Pertanika Journal of Tropical Agricultural Science showed that Arabica coffee extract has some ability to combat ants, but that even that variety had an overall low efficacy. Other scientific publications more broadly claim coffee can kill insects and that pollinators like bees actually get a buzz from caffeine, but further evidence suggests that ants specifically may not mind it all that much. They definitely don't like the smell of coffee, but they also don't appreciate other strong smells like cinnamon or peppermint, meaning coffee grounds may not be uniquely effective.

With all this contrary evidence, you may be wondering if you should just toss your coffee grounds, or even reuse them to brew more double-strong coffee as a water substitute (spoiler alert: don't do that). Here's the lowdown: coffee grounds have some limited use as a physical barrier for ants, but only temporarily. David Price, an entomologist, told The Spruce that coffee can disrupt ants' pheromone communication, but only as long as they are physically blocked by the coffee grounds. "As soon as the ants work out a way around the grounds, it's no longer a solution," Price concluded. If you know that ants are coming in through, say, a faulty window seal, you might be able to use coffee grounds to deter them from entering via the gap while you work out a permanent fix. However, ants will eventually figure out a way over or around the grounds, and that's if they don't physically move the coffee themselves!

Sadly, when it comes to ants, careful use of an actual pesticide is probably your best option. Using Borax laced with sugar is a well-tested solution that doesn't involve those strong-smelling bug sprays, although it cannot be considered fully non-toxic. Keeping your kitchen very clean and sealing any cracks and openings in walls and windows is also a good preventative step. As for your coffee grounds? You can recycle them as fertilizer for your garden soil, so they aren't wholly useless after all.