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　　Ever lit a citronella candle to ward off mosquitoes,only to have 'em appear in droves?

　　Well, believe it or not, you may have actually beenattracting the bugs.

　　Because while high concentrations of those pine-and-lemon-scented chemicals might repelmosquitoes, at low concentrations they lure the bloodsuckers in.

　　Audrey Odom, who studies mosquitoes at Washington University, calls it the "Chanelhypothesis."

　　Too much perfume is awful, but a little is pretty nice.

　　Plants take advantage of that to advertise their nectar—because no, mosquitoes don't live onblood alone.

　　But here's where things get weird.

　　Plasmodium—the malaria parasite—also manufactures those alluring odor molecules, calledterpenes.

　　It does so using a chloroplast-like organelle, like the one plants use to capture sunlight.

　　The malaria parasite's version can't trap light, but it can still manufacture plant perfume.

　　The study appears in the journal MBio.

　　The parasites produce these scents in the lab, and mosquitoes are attracted to them.

　　The only question left for Odom and her colleagues is whether these chemicals also appear inthe breath of infected humans.

　　If they do, she says, the goal is to build a quick breathalyzer test for malaria, instead of theblood test used today—which would attract doctors to a patient in need before the nextmosquito comes to bite.