Fleas are insects of the Siphonaptera order. They are exceptionally small rounded insects with short legs that lead to mammoth hind legs. They, like all insects, are comprised of an abdomen, thorax and head. Fleas are external parasites which live by feeding on the blood of mammals and birds. Fleas are also built for moving through the hairs of an animal and for being able to leap 200 times their body height. Their genitals are located in the rear of their body.
Fleas reproduction is highly centered around the availability of blood. Adult fleas can only reproduce when they are full of blood. When both male and female flea have been fed, the male will attach himself either with suckerlike appendages on his antennae or will grasp her hind legs with hooks on his abdomen. Once he is locked onto her, he will deposit sperm directly into her reproductive organs.
The female will typically lay eggs in locations with nesting mammals or birds so that her young can have access to food. In her lifetime, a female flea can lay up to 500 eggs.
Eggs are laid in groups of twenty or more and are laid on the hosting animal. Flea eggs take 2 days to 2 weeks for hatching. Newborn fleas are highly defenseless and have little to no sensory ability.
Fleas go through three life cycle stages: larva, pupa and adults.
With enough blood, over time, the pupate will enter a cocoon and, in about 14 days, will emerge into the next phase. After another 14 days, they will grow into an adult flea. Adult fleas then begin to hunt for new food sources and opportunities to continue their reproductive cycle.