Life Cycles

1. Female fleas lay as many as 50 eggs a day, starting a life cycle that can be completed in as little as three weeks, depending on temperature and humidity.

2. The eggs hatch into larvae that feed on "flea dirt," the excrement of partially digested blood.

3. Larvae grow and molt twice, then spin cocoons, where they grow to pupae and then adults.

4. The adult remains in the cocoon until vibrations indicate a host is nearby. This waiting can extend the life cycle. It also explains why large numbers of fleas often are seen when an empty building is reoccupied.

5. Six-legged adults emerge and attach to a host to feed and breed, beginning the cycle all over again.

Tick Life Cycle

1. Adult females of some species lay about 100 eggs at a time. Others lay 3,000 to 6,000 eggs per batch.

2. Six-legged larvae hatch from the eggs.

3. After at least one blood meal, the larvae molt into eight-legged nymphs - in some species, more than once.

4. Final nymphs molt into adult males or females, also with eight legs.

5. Depending on its species, a tick may take less than a year or up to several years to go through its four-stage life cycle. While ticks need a blood meal at each stage after hatching, some species can survive years without feeding.