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Science & Technology

October 30, 2006
Volume 84, Number 44
p. 42

What's That Stuff?

Citronella Oil

Mixture of terpenes in plant oil provides a relatively safe way to stave off pesky flying insects

Steve Ritter

Once upon a time, I could tolerate mosquitoes, gnats, sweat bees, and other annoying insects. But when Asian tiger mosquitoes invaded the southeastern U.S. in the 1990s and later infiltrated the area where I live in northern Virginia, I quickly lost my tolerance.

Steve Ritter/C&EN

These mosquitoes are tenacious rascals not to be taken lightly. Unlike common mosquitoes, tiger mosquitoes are active both day and night, in cool weather and in blazing heat and high humidity. They only need a thimbleful of water for breeding and are unbelievably quick to dodge a hand smack. So at our house, after getting tired of being eaten alive and leery of drenching ourselves all the time with a synthetic insect repellent, we ran out and bought some citronella-scented candles.

On a weekend a couple of months ago, I was sitting around at the tail end of a cookout, waiting for the sun to fade on the horizon, with nothing on my mind except being lazy. By and by, I got nudged back into reality by a few puffs of smoke from the candles burning close by. The almost sickly lemony smell was welcome as it kept the mosquitoes from gnawing on my ankles and allayed my minor concern over the transmission of diseases such as encephalitis or West Nile virus. It finally struck me to do a little research to find out exactly what the active chemicals are in this natural insect repellent.

Citronella oil