Adult deer ticks wait in vegetation for an unsuspecting host—deer, dog, cat, or human—to hitch a ride. The tick waves its first pair of legs in an outstretched position and detects the host by a combination of its carbon dioxide production, body heat, moisture levels and vibrations—a behavior called “questing." The deer tick feeds once in each stage of its life cycle—larva, nymph, and adult. Each time the tick feeds it could pick up the bacteria that cause Lyme disease (Borrelia burgdorferi) from an infected animal. Although the deer tick carrying the bacteria is healthy, the next time it feeds it will most likely pass them on to an animal. For example, in the Northeast USA, the larva may feed upon an infected white-footed mouse, vole or chipmunk. Then the next time the tick feeds as a poppy seed-sized nymph or a sesame seed-sized adult, it passes the bacteria on to a deer, dog, cat or human. Only deer ticks spread Lyme disease, and in some highly endemic areas in the Northeast and Midwest USA as many as one in four ticks are carrying the bacteria that cause Lyme disease. Removing the tick as soon as possible may prevent infection.
Photographed at Van Buren State Park, Michigan.
Graham Hickling, PhD, Dept. Forestry, Wildlife and Fisheries, University of Tennessee, Knoxville, TN