What’s the best way to keep mosquitoes from biting you? The answer, according to a Wall Street Journal interview with Stephen Gluckman, professor of medicine at the Perelman School of Medicine at the University of Pennsylvania, and a specialist in infectious diseases, is the same as it has been for years: DEET. Gluckman’s answer comes from the most comprehensive comparative study that he has seen, published in the New England Journal of Medicine in 2002. That study tested 16 products on the arms of volunteers, which were extended into a cage filled with mosquitoes. The Journal reports that DEET kept the the bugs away for 301 minutes, while citronella oil protected volunteers for 20 minutes. What about garlic? Nope, says Gluckman. No study has shown that to be more effective than a placebo.