Fleas are obligatory blood feeders parasitizing warm-blooded invertebrates. More than 94% of known species are parasites of the mammals and only about 5% of them occur on birds.
The fleas have 4 phases of development - the egg, the free-living larva, the exarate pupa and the imago.
The larvae is wormlike, legless and eyeless with biting mouth parts. The larvae undergoes 3 instars. Prior to pupation it empties the alimentary canal, and spin a silken cocoon.
The majority of fleas are closely associated with the host's home (nest, burrow etc), attacking the host for feeding.