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Who doesn’t appreciate the smell of coffee? Mosquitos–apparently. Burned used coffee grounds are being hyped as a natural mosquito repellant. Does this really work? Here’s the scoop.
There seem to be no definitive studies on the efficacy of coffee grounds as a mosquito repellant. Mosquitos–and other insects–tend to avoid strong smells like citronella, incense, vinegar, essential oils, etc. Strong smells mask the odors that attract mosquitoes to humans and other warm-blooded animals. The smoke from burning coffee grounds helps to deter them.
- The Journal of the American Mosquito Control Association quotes a study about the significant amount of smoke created from burning coffee grounds repelling mosquitos and that there was some residual effect.
- A study in the Journal of Insect Science suggests that coffee grounds sprinkled on standing water could prevent mosquitoes from laying eggs. Or that it might kill larvae. However, the study only included one species of mosquito. It also found that the value of coffee grounds as a repellent varied according to the species.
- Another study suggested that coffee grounds may provide nutrition for some species of mosquitoes.
- Coffee grounds have not been registered with the Environmental Protection Agency as a mosquito repellent.
Rubbing coffee grounds on your skin or spraying on liquid coffee does not work as a repellent.
How To Use Coffee Grounds On Mosquitos
Burning is the most effective way of using coffee grounds to repel mosquitoes. Both fresh and used grounds work equally well. The used grounds need to be completely dry before use. Coffee grounds do not burst into flames. They smolder and create lots of smoke. Some suggest that the smoke drives off mosquitoes rather than the smell of coffee.
Pour the grounds into a non-flammable and non-meltable container like a used citronella jar or foil plate. Heap them into a pyramid shape and insert a wick. As the wick burns down, it sets the coffee grounds smoldering. The grounds act like charcoal and will continue to burn for hours.
You can use liquid or solid barbecue starter to light the coffee grounds. A match or electric barbecue starter also work.
Coffee grounds appear to have some mosquito-repelling qualities but it is not a very strong repellant. If it works on the species of mosquitoes where you live, keep using it. Coffee grounds are a byproduct costing nothing but a little time and effort.
If coffee grounds don’t work, there are plenty of other options including:
- Citronella Candles. For patio parties.
- Essential Oils. Such as lavender and peppermint spread on bare skin. Add a few drops to the burning coffee grounds for a more pleasant odor.
- Deet. Very effective chemical repellant when sprayed on skin. Does not have a pleasant odor. Some people have reactions to Deet.
