By Roberta Attanasio Blacklegged ticks feed on blood — they attach to the skin of humans and many animals and, slowly, suck for several days. To get there, they patiently wait on the tip of grasses and shrubs using their lower legs to hold on, until a human or an animal passes by. Ticks can’t jump or fly, so they keep their upper pair of legs outstretched, ready to climb aboard. Once there, they insert their feeding tube into the skin and start to suck the blood — this is how they become infected by or transmit Borrelia burgdorferi, the micro-organism that causes Lyme disease. Lyme disease is one of the most common infectious diseases in…