Can Coffee Grounds Repel Ants? Pest Experts Explain What Really Works

Almost as inevitable as death and taxes, ants invading your home is a nuisance most people would rather avoid. While commercial sprays are one way to deal with the problem, many people have turned to natural alternatives instead—including coffee grounds.

If you've ever sprinkled used coffee grounds around your kitchen or garden in hopes of keeping ants away, you're not alone. It's one of the most common DIY pest-control tips online. But does it actually work? We turned to entomologists and pest experts to find out.

Can Coffee Grounds Repel Ants?

In searching for a natural deterrent for the ants traipsing around your kitchen sink, you might have considered reaching for the remnants of your morning cup of coffee. Unfortunately, this oft-touted method lacks efficacy. “Coffee grounds aren't a great long-term solution for ants,” says board-certified entomologist Dr. Hamilton Allen. “Depending on the ant species, coffee grounds may offer a very minor level of repellency—but not enough to provide suitable relief.” 

While the scent of coffee grounds can help mask an ant's scent trails, it's only a temporary deterrent. “It might be effective for a day, but that's about it,” says pest control company owner Jeff Schumacher. “I wouldn't count on coffee grounds as a permanent or even effective solution."

In fact, it might even make the problem worse. “If you have ants already in your walls and you put a barrier of coffee grounds around the base of your house, you will push them up in your walls further,” explains Matt Smith, a licensed professional pest control technician. “It can cause a colony to split and start a new one.”

Other Natural Methods That Work

Instead of coffee grounds, try diatomaceous earth, or DE. “It is a naturally occurring substance that can be used as an insecticide when applied directly or indirectly to an insect's body,” explains Allen. “The material has absorbent and lacerating properties and essentially ‘dries' an insect out through the removal of essential oils and fats present on the exoskeleton.” 

Use DE for small indoor ant infestations. “To be effective, the ants must come in direct contact with the substance—so proper application to infested areas is key,” Allen says. “Pouring large amounts on your countertop will be ineffective, as the ants will begin to avoid the powder.”

Cinnamon, cayenne pepper, and peppermint oil are all scent-based natural deterrents that help create a barrier ants might avoid. “You do have to use a pretty liberal amount to keep ants away long-term, because they are smart and will eventually get through,” Schumacher says. 

Many people also plant ant-repellent herbs near entryways that help keep many pests away. “Things like mint, lavender, or basil are the most common,” Schumacher continues. “None of these natural methods get rid of the colony, but they will encourage ants to avoid certain areas."

Best Preventative Methods

To prevent ants from getting into your home and living spaces, focus on these areas: 

• Clean up crumbs:  Three areas where food particles tend to collect are the oven, microwave, and toaster. “The space between the stove and counter can be protected with guard covers made of stainless steel or rubber,” Allen says, “and crumbs beneath microwaves and toasters should always be cleaned.” 
• Secure food items: Store cereals and grains in reusable Ziploc bags or storage containers in your pantry. “Ants are strong,” Allen says, “but not strong enough to pull off a tight-fitting lid.”
• Keep moisture at bay: Fix leaking pipes and appliances as soon as possible. “Further, if your refrigerator has exterior condensation, check your temperature settings and/or the number of items inside,” Allen says. “Too many food items can lead to an improper seal and the escape of cool air to the outside.” 
• Perform regular inspections: Inspect your home for gaps around doors, windows, and exterior pipes leading to your home, says Allen. Seal any gaps to keep pests out. 
• Maintain landscaping: The best way to help prevent ants from coming into your home is to clear out the area along the foundation. “Don't have vegetation or other debris right up against the house,” Smith says.

When to Call a Professional

The decision to contact a pest control provider boils down to personal pest tolerance. “Generally, a single ant or two aren't major causes of concern,” Allen says. “However, if you see more than five or 10 ants repeatedly in the same space or multiple locations within your home, get someone on the phone who can provide a thorough inspection, identify the root cause of presence, and prescribe a solution perfect for your living space.”

However, if you have carpenter or fire ants, call in a pest control expert as soon as possible. “Carpenter ants are destructive and will cause serious damage to your property if they aren't addressed promptly and thoroughly,” Schumacher warns. “Fire ants are dangerous and nearly impossible to eliminate using DIY methods.”