Without having an understanding and appreciation for the life cycle of the flea it's impossible to gain control over a flea infestation. This is because approximately 5-10% of a potential flea population is in the adult stage at any one time. As you will soon discover, because of the small size and nature of the flea in its immature stages, it's only the adult flea that we come in contact with. This means that 90-95% of the fleas in a pet's environment are developing in the other three stages of life that you don't see and therefore are not aware of. It's these other stages of life that allow an ever continuing development of fleas even when all the adult fleas of a current generation are killed. This is why you can use an OTC insecticidal fogger one day and kill all the adult fleas in a room, and find new fleas the very next day. Chances are the fogger will not kill developing fleas in all immature stages of life and new fleas will emerge to begin a new reproductive cycle all over again. There are products available that kill all four stages of the flea. Mycodex Environmental Control is what we recommend.
There are four distinct stages in the life of a flea: the egg, the larvae, the cocoon (or pupal), and the adult. The flea's entire life cycle can be as short as three weeks or greater than six months, depending upon external conditions. The ability to sense a host animal and environmental conditions (temperature and humidity) are the two most important factors affecting the longevity of the flea.
Flea eggs are small, pearly¬ white, and oval in shape. They're about 0.5 millimeters long and are just visible to the naked eye. The eggs are usually laid while the female flea is on the host animal. Because they're very smooth, the eggs fall off the host animal easily and, thus, are spread all over a home by a free roaming pet. Flea eggs generally hatch after a period of 1 to 10 days.
When a flea egg hatches, a 2 ¬millimeter¬ long, legless, white larva emerges looking like a tiny worm. This stage, which is easier to see with the aid of a magnifying glass, generally lasts 5 to 11 days, but could last up to a month.
During this stage, larvae almost constantly look for food. They feed on organic matter, such as skin scales (a common component of dust), tiny insect parts, and, most importantly, adult flea fecal material, or flea droppings, which consists of dried, but undigested blood. Flea droppings look like small pieces of dark dirt when seen on an animal's skin, in its hair, or around its sleeping area.
Development during this stage takes place off the host animal, quite often in or near a pet's bedding and sleeping areas. The larvae, having worm¬like characteristics, prefer a dark environment and will burrow down into any available materials, with carpeting, furniture fabric, underneath furniture cushions, and cracks in floors (especially wood floors) being particular favorites inside a home. Larvae generally won't develop in areas that receive direct sun unless they're protected from the heat and light. Notorious places for development outside the home include: inside pet houses, under porches and decks, and under favorite trees and shrubbery.
The larvae spin small, whitish, silken cocoons, 5 millimeters long, (called pupae) where the worm¬like creature from the last stage develops into the adult flea that we're familiar with. This process is called metamorphosis. The outside of the cocoon is very sticky and quickly becomes camouflaged with a layer of dust and dirt. Cocoons are typically found in areas that are hidden from sight and protected from environmental dangers. The base of carpet fibers is a particularly favorite area for larvae to spin cocoons. Unfortunately, a thick carpet is a main reason why cocoons are often protected from insecticidal sprays and foggers. These products just cannot penetrate a thick carpet canopy to contact the cocoon. This is why a new generation of fleas can be born the day after all the adults were killed by using an insecticidal fogger.
The length of time for this stage can also vary greatly. The adult flea may emerge from its cocoon after only one week or may not emerge for over 6 months. In addition to favorable environmental conditions, there are two particular activities that will cause a flea to emerge from its cocoon. These are: the warm temperature and pressure of a sleeping animal on the cocoon in a pet's resting area, and vibrations caused by a host walking into an area.
The ability of the flea to prolong its life span, especially in the cocoon stage, is a major reason why the onset of warmth and increase in humidity towards the end of spring and beginning of summer can cause an explosion of flea activity. It is also the reason why fleas are notorious for attacking people when an unoccupied room or home is entered. These are newly emerged adult fleas that have been stimulated to hatch by the movements of someone walking near them.
Immediately upon emerging from its cocoon, the new adult flea, about 2.5 millimeters in length, begins looking for a suitable host. Both male and female fleas bite and suck blood to sustain themselves and provide food for their offspring. The life span of the adult female can be as long as several months during an active "flea season" or longer during a less active time, while the male's life is thought to be about half that of the female's.
The number of eggs a typical female flea is capable of laying per day or over her life-span varies greatly. Estimates from observations indicate that some female fleas can lay 20 to 50 eggs per day, and that this level of production can continue for 3 months or more. Thus, each female flea may be able to lay over two thousand eggs during her lifetime, and if undisturbed, her entire reproductive life can be spent focused on a single host animal. Multiply two thousand eggs by the number of female fleas on a pet (two out of three fleas found on your pet will be female) and you begin to appreciate the term "flea infestation."