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. Deer ticks (Ixodes scapularis) have four stages in their life cycle: egg, the 6-legged larva, and 8-legged nymph and adult (male or female).

The deer tick has a two-year life cycle, which can have a direct bearing on your chances of becoming infected with Lyme disease. Adult deer ticks are active from October through early December, and then again in April and May. They commonly attach to white-tailed deer, dogs, cats, and people if they are active out of doors in tick prone areas. In Albany County, adult deer ticks may be active anytime the temperature is above 35 degrees, even during the winter months with snow on the ground.

In late summer, the larval tick hatches from the egg and feeds on mice and other small rodents, which are the source of the Lyme disease bacteria. Once the tick becomes infected with the Lyme disease bacteria it carries the infection through its' next two life stages. The larva molts to the nymph stage the following spring.

Nymphs, which cause about 80% of the cases of Lyme disease in humans, are active in the late spring and summer (May through September). Because they are only about the size of a poppy seed they can be very difficult to see. When ready to feed, nymphs climb onto a blade of grass or similar vegetation to await a host.

Ticks detect their hosts through several host odors, including carbon dioxide, body heat, moisture, vibrations and visual clues such as a shadow. When a host brushes against the vegetation, the tick will cling to the host. Ticks cannot fly or jump; they must make direct contact with a host. Once on a host a tick may attach to the skin quickly or wander over the host for some time before attaching.

By late summer, nymphs molt into the adult stage. During the adult stage, only the female deer tick takes a blood meal. This usually occurs in the fall or spring. After taking a blood meal, the female ticks lay their eggs and the cycle begins again.

Albany County has many areas with the type of landscape ideal to support the animals necessary for a Lyme disease problem to exist. Partial forests and open fields make these areas well suited for deer and white-footed mice. In the complex scheme of Lyme disease ecology, deer are critical because they are the main host for reproducing adult ticks. Mice are important because their bodies store the Lyme disease bacteria and spread it to larval deer ticks.