The Life Cycle of a Tick

Most types of ticks require three hosts during a two or three year lifespan. Each tick stage requires a blood meal before it can reach the next stage. Hard ticks have four life stages: egg, larva, nymph, and adult. Larvae and nymphs must feed before they detach and molt. Adult female ticks can engorge, increasing their weight by more than 100 fold. After detaching, an adult female tick can lay approximately 3,000 eggs.

Adult females drop off the host to lay eggs after feeding, usually in the fall. During the egg-laying stage, ticks lay eggs in secluded areas with dense vegetation. The eggs hatch within two weeks. Some species of ticks lay 100 eggs at a time, others lay 3,000 to 6,000 per batch.

Eggs hatch into six-legged larvae and overwinter in this larval stage. When spring comes, the larvae move into grass and search for their first blood meal. They attach themselves to their first host, usually a bird or rodent. Later in the summer, engorged larvae fall onto the ground and molt into nymphs, usually in the fall.

Nymphs (which are generally the size of a freckle) remain inactive during winter and start moving again in spring. During the following spring, the nymphs seek out and attach to the second host, usually a rodent, pet, or human.

The nymphs feed on the second host and after this blood meal, fall off the host and molt into adults - off the host - in the late summer or fall. Throughout the autumn, the male and female adults try to find a host, which is again usually a rodent, pet, or human. If adults cannot find a host animal in the fall, they can survive in leaf litter until the spring.

The next spring, adults seek out and attach to a third host, which is usually a larger herbivore, carnivore, or human. The adults feed and mate on the third host during the summer.

The adult female feeds for 8 to 12 days. The female mates while still attached to her host, then both ticks fall off, and the males die. The female remains inactive through the winter and in the spring lays her eggs in a secluded place.

Females may reattach and feed multiple times. The three hosts do not necessarily have to be different species, or even different individuals. Also, humans may serve as first, second or third hosts.

source: Parasites and Health at the Center for Disease Control