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An illustration of a common flea. Once the flea reaches adulthood its primary goal is to find blood - adult fleas must feed on blood in order to reproduce. Adult fleas only have around a week to find food once they emerge, though they can survive two months to a year between meals. A flea population is unevenly distributed, with 50 percent eggs, 35 percent larvae, 10 percent pupae and 5 percent adults. Their total life cycle can take as little as two weeks, but may be lengthened to many months if conditions are unfavorable. Female fleas can lay 500 or more eggs over their life, allowing for phenomenal growth rates.

Flea

An illustration of a common flea. Once the flea reaches adulthood its primary goal is to find blood…

An illustration of the larva of a common flea. Flea larvae emerge from the eggs to feed on any available organic material such as dead insects, feces and vegetable matter. They are blind and avoid sunlight, keeping to dark places like sand, cracks and crevices, and bedding. Given an adequate supply of food, larvae should pupate within 1-2 weeks. After going through three larval stages they spin a silken cocoon.

Flea Larva

An illustration of the larva of a common flea. Flea larvae emerge from the eggs to feed on any available…

An illustration of the pupa of a common flea. After going through three larval stages they spin a silken cocoon. After another week or two the adult flea is fully developed and ready to emerge from the cocoon. They may however remain resting during this period until they receive a signal that a host is near - vibrations (including sound), heat and carbon dioxide are all stimuli indicating the probable presence of a host. Fleas are known to overwinter in the larval or pupal stages.

Flea Pupa

An illustration of the pupa of a common flea. After going through three larval stages they spin a silken…

The human flea (Pulex irritans) is a parasite in the the Siphonaptera order of fleas.

Human Flea

The human flea (Pulex irritans) is a parasite in the the Siphonaptera order of fleas.