Fleas come in various types, but all types have the same general four-stage life cycle. The life cycle of a flea begins with an egg. When the egg hatches, the flea enters the second stage, called the larva stage. The third stage of the life cycle is known as the pupa stage. Finally, the flea becomes an adult, which is the last stage of its life cycle.
The life cycle of a flea continues year round and starts when the female flea lays its eggs. A flea egg is a pearl-white oval a little smaller than a grain of sand. A female flea can lay upwards of 50 eggs a day and generally will lay around 500 to 600 eggs during its lifetime. Flea eggs prefer a warm and humid environment and, if conditions are right, can hatch in one to five days. If the conditions are less than favorable, hatching could take several weeks.
The second stage in the life cycle of a flea, called the larva stage, occurs when the egg hatches. The larva emerges from the egg using a chitin tooth, which is a hard spine on head that later disappears during molting. The larva is translucent white, generally about 0.25 inches (6.35 mm) long, and has small hairs along its body, which help it to move. Flea larvae generally eat the excrement of adult fleas and will go through three molting stages before forming a cocoon. The time it takes a larva to complete its molting can vary greatly, and the larva stage can last anywhere from six to 36 days.
When the larva forms a silky cocoon around itself, the third stage in the life cycle of a flea has begun. The pupa stage usually lasts from seven to 10 days. The pupa, however, can lay dormant for a year or more awaiting the right conditions to emerge. Generally, warm temperatures, high humidity, and the vibrations caused by potential host animals passing nearby can all signify to the pupa that it is time to emerge.
Adulthood is the final stage in the life cycle of a flea. When the flea emerges from the cocoon, it usually has a dark-colored exoskeleton covered with coarse bristles. The adult flea has three pairs of legs with the back legs designed for jumping. An adult flea can live up to two years before its first blood meal, but once it has its first blood meal, it must feed every four to six hours in order to survive. On average, a flea will live 12 days on its host after its first blood meal, and a female will lay eggs within two days of attaching to the host animal.