Burning coffee grounds not proven method to prevent mosquito bites

ST. PETERSBURG, Fla. — It’s peak mosquito season here in Florida, so what’s the best way to keep those pesky bugs at bay?

One viral “hack” repeated in several posts and videos on social media claims burning coffee can do the trick.

“Citronellas on steroids,” is how one TikTok user referred to it.

But is there any truth to this so-called trick?

THE QUESTION

Can burning coffee grounds really get rid of mosquitoes?

THE SOURCES

• Alissa Berro, Pinellas County mosquito control and vegetation management director
• Study on coffee and impact on mosquito larvae (2015)
• Centers for Disease Control and Prevention (CDC)

THE ANSWER

Burning coffee grounds is not a proven mosquito repellent but studies have found some plants offer alternative, effective natural repellants.

WHAT WE FOUND

Alissa Berro, who is the mosquito control and vegetation management director for Pinellas County, says there is no research showing coffee is effective at repelling mosquitoes to prevent people from being bitten.

The only significant peer-reviewed study she’s aware of examined the potential for coffee grounds to prevent mosquitoes from breeding. The 2015 study found mosquitoes laid fewer eggs in water with coffee than without.

“Somebody's always coming up with a new hack,” Berro said. “And oftentimes, it may have a kernel of truth but a lot of times it doesn't effectively protect you from mosquito bites."

However, some studies have examined the efficacy of other natural repellants, like citronella and oil of lemon eucalyptus. This study found oil of lemon eucalyptus had similar efficacy to DEET.

“It matters what you’re burning,” Berro said. “Plants always have some sort of chemical makeup in them… used to try and protect themselves from insects gnawing on them and trying to attack them and so we do see these different chemicals and oils and plants that do have repelling properties for mosquitoes.”

When it comes to protecting yourself from mosquitoes, Berro said to stick to the tried-and-true methods recommended by the Centers for Disease Control and Prevention and others:

• Wear long, loose-fitting clothing
• Dump all standing water
• Use EPA-registered insect repellents.

EPA-registered insect repellents are proven safe and healthy, according to the CDC, because they contain at least one of the following active ingredients:

• DEET
• Picaridin
• IR3535
• Oil of lemon eucalyptus (OLE)
• Para-methane-diol (PMD)
• 2-undercanone

“It's the same every year and while that gets boring, we always recommend it because it really is the best way to get rid of mosquitoes and help protect yourself,” Berro said.