All ticks are parasites in that they must locate, attach to, and feed from an animal or human in each stage of their life cycle.

The deer tick has a two-year life cycle, which can have a direct bearing on your chances of becoming infected. Adult deer ticks are active in October-November, and then again in April-May. They commonly attach to white-tailed deer, dogs, horses, and people if they are active out of doors in tick prone areas. In Columbia County, adult ticks may be active anytime the temperature is over 35 degrees, even with snow on the ground.

In late summer, the larval tick hatches from the egg and feeds on mice and other small rodents, which serve as the reservoir for the Lyme disease bacterium. The larva molts to the nymph stage the following spring.

Nymphs, which cause most of the cases of Lyme disease (about 80%), occur in late spring and summer (May through September) and are about the size of a poppy seed. The nymph waits in ambush on vegetation from ground level to about 18 inches high. When a host brushes against the vegetation, the tick clings to it and searches for a suitable feeding site. By late summer, nymphs molt to the adult stage, which feed in the fall and spring, and then lay their eggs and the cycle begins again.