The life cycle of Fleas
Fleas undergo complete metamorphosis from eggs to adult. Adult fleas cause a range of clinical issues, pupae cause absolutely no problem. However, flea eggs and larvae make up more than 50% of the entire flea population.
Adult fleas may be the smallest in population but they account for the major flea issues. They do the mating, laying and biting. They break out of their cocoons when they sense the presence of a host. Once a flea attaches itself to a suitable host, they start the cycle of reproduction again.
Female fleas lay a minimum of fifty eggs per day after feeding. They usually appear whitish, oval and very tiny like a grain of sand. Immediately they are lain, the eggs fall off to the ground because they are non-sticky. After six days, it hatches into larvae.
These are worm-like and whitish in color, they break out of the egg with the aid of a spine on the head. The spine disappears after the larval molt. They detest light and so after hatching they will crawl away from open spaces and hide in crevices, around pet beddings and other shaded areas. They do not feed on blood but on the adult flea excrete or any organic matter/dirt. In the following molt, they form cocoons from where they develop into pupae.
At this stage, virtually nothing can harm the protected adult flea. Most insecticides and pesticides are not formulated to penetrate the silken cocoon. They can remain protected for months even if the normal time is a week or two. If the conditions are not suitable then they will not emerge. The encased adult flea emerges when there is an available host to feed on by sensing a change in the rise of carbon dioxide.
In the end, this points to the fact that adult fleas are only part of the problem so control all stages to remove every sign of infestation completely.