Does burning coffee grounds repel mosquitoes?

I've heard that burning coffee grounds keeps mosquitoes away. Is this actually true, or is it just one of those internet myths?

Burning coffee grounds produces smoke, and mosquitoes are weak flyers that tend to avoid smoky environments. The strong smell of the smoke may also help mask the carbon dioxide and body heat that mosquitoes use to find you. So in a small, relatively enclosed outdoor space, it can offer some short-term relief.

That said, the effect of burning coffee grounds as a mosquito repellent is limited because any breeze will quickly scatter the smoke. If you're getting bitten regularly, a smoldering pile of grounds won't cut it. Applying a DEET-based repellent to exposed skin is a much more reliable option for personal protection outdoors.  

The bigger issue is often what's happening in your yard. Mosquitoes breed in standing water, and even a small amount can support hundreds of larvae. A clogged gutter or a forgotten plant saucer is all it takes, and no amount of smoke can address that. For lasting mosquito control, a professional approach is a more effective approach.