Bloodsuckers don't have the best reputation, if those itchy mosquito bites from last summer have anything to say about them, but before you jump to any conclusions, these little pests are more than meets the eye. Everyone knows about high-jumping fleas, classic vampire bats, and shudder-inducing leeches, but how about blood-sucking birds, butterflies and snails? Did you know that only 15-20 percent of people react to bed bug bites? Or that there...