The larva, nymph (shown here, engorged), and adult of the lone star tick (Amblyomma americanum) have piercing mouthparts that they use to draw blood from animals. A bite to a human can cause itching and burning welts, as well as other allergic reactions, and may also transmit disease-causing pathogens that can cause illness and, if left untreated, death. (Photo by Ilia Rochlin, Ph.D.)