"Ticks only need a drop of blood a year to survive," says Paul Tukey, founder of Safe Lawns, and organic lawn-care company. "So they're just waiting to get it from a mouse, a deer, or, of course, you." There are more than 800 species of ticks on the planet, and some of them can carry life-threatening diseases, including Lyme disease and the dreaded Rocky Mountain spotted fever. "Ticks don’t usually hang out in open, full-sun lawns,” says Tukey. "But you might find plenty of them on the fringes, in more shaded areas." Avoid bites by wearing shoes and socks while doing yard work.