By DR. FRED SELF / Veterinarian

As humans, we are familiar with a very standard form of life. You have parents, you are born, you carry out the components of childhood, middle age, old age, and then you die.

The parasites that pester our pets do not follow the same rules. Some, for instance, carry out the cycle we might consider life on one host and then inhabit another host and participate in a second life cycle.

Other pests, like the flea, only go through a single cycle but are able to arrest, or stop, some of the stages in the cycle and then continue them when conditions are more favorable. The flea starts its life as an egg. Each egg can hatch and develop into a single flea larva. The flea larva lives in the environment, indoors or out, and feeds. As it feeds, the larva stores up energy. Once a sufficient amount of energy has been stored, the larva develops into a pupa. The pupa form allows the flea to hangout in the environment without being subjected to any harsh conditions. The pupa is a house-like structure that surrounds the developing flea and keeps it safe until the proper conditions are present. When the flea has developed to the proper form within the pupa, it can hatch immediately or it can wait for the right conditions.

Once the adult flea has hatched, it travels through the environment looking for a host on which to live and feed. The adult flea takes a blood meal from its host. Once the blood meal is taken the female is prepared to start laying eggs. Each egg produced can decide on its own the best time to hatch. If the conditions are not right, flea eggs can wait for months to hatch. When conditions are right the egg will hatch and the cycle will begin again. The ability to stop its life cycle allows a flea the best chance to survive. By making decisions based on surface vibrations, carbon dioxide levels and temperature, fleas can choose to enter the next stage in the life cycle when the appropriate host is present. This way they have a good chance to find a food source and a safe place to live. While this works well for fleas, it can be tough on pet owners. Pet owners who take a long vacation can come home to a large flea hatch.

Dr. Fred Self is a veterinarian at Shelbiana Animal Clinic in Columbiana, along with Dr. Charles Thornburg. You can reach them at 669-7717.