The blacklegged tick (Ixodes scapularis) is the primary vector of the bacteria that cause Lyme disease, which can lead to joint and nervous system complications. This photo shows a mating pair (the male is much smaller) that was collected from a canine at an animal shelter. The U.S. Centers for Disease Control and Prevention (CDC) estimates that nearly a half-million Americans may be infected with Lyme disease each year. (Photo by Kyndall Dye-Braumuller, BCE)