Ixodes dammini is responsible for most of the cases of Lyme disease in the northeastern United States. These ticks are found in grassy areas (including lawns), and in brushy, shrubby and woodland sites, even on warm winter days. They prefer areas where some moisture is present. The tick has three life stages: larva, nymph and adult. Each stage takes a single blood meal. They feed on a variety of warm blooded animals including man, dogs, cats, horses and cows. The bite is painless so most victims do not know they have been bitten. The nymphal stage appears to be responsible for most Lyme disease cases. Both the larval stage (about the size of a grain of sand) and nymphal stage (about the size of a poppy seed) attach to a variety of small mammals, but prefer the white-footed mouse, the main reservoir of the Lyme disease bacteria. The adult ticks (about the size of a sesame seed) prefer to feed on white-tailed deer. The entire life cycle requires three separate hosts and takes about two years to complete.
Larval and nymphal deer ticks also attach to birds. Indeed, birds may be a primary means by which the ticks (some infected) are spread from one area to another. Some species of birds also function as a reservoir of infection.