Many of the best family memories are made while sitting on a porch on a summer evening in the South. Until the mosquitoes come out anyway.

As the spring gives way to summer and we all spend more time outside, mosquitoes become a real pest and most people look for ways to repel the little bloodsuckers.

While dousing your family in DEET may be effective, many families prefer a more natural alternative, like citronella. Citronella is an oil derived from the leaves and stems from a cousin of lemongrass (specifically, Cymbopogon). While most humans don’t mind the light citrus scent, mosquitoes reportedly hate it, so citronella is used in a variety of products like candles and wristbands and sprays. But does citronella actually work? Not as well as we’d like.

Last year, scientists decided to study what is the best way to keep mosquitoes away. They tested 11 types of repellents, including five sprays, five wearable devices, and a citronella candle, on Aedes aegypti mosquitoes—the little monster that is responsible for delivering Zika, yellow fever, dengue, and other diseases. 

For their test, the scientists tried to recreate the conditions in someone’s backyard patio with a human as bait for the mosquitoes. Their report, which was published in the Journal of Insect Science, showed that citronella flunked the test, but it wasn’t alone. Those bracelets that contain herbal extracts and the sonic mosquito repellers, that claim to use high-frequency sound to drive away mosquitoes both resoundingly failed at their jobs. If you’re looking for a device, the study found that only the OFF! clip-on fan containing the insecticide metofluthrin worked well.

The repellants that worked were DEET and in a bit of good news for those of us who prefer a more natural approach, oil of lemon eucalyptus sprays, which comes from the gum eucalyptus tree, reduced mosquito attraction by 60%. That’s probably why the Center for Disease Control, includes oil of lemon eucalyptus spray on its list of recommended mosquito repellants, but does not include citronella. Consider that the next time you’re looking for a way to keep the mosquitoes away so you can continue to enjoy your summer evenings.