A female flea will lay several hundred eggs, normally laying four to eight eggs after each blood meal, and building up to the highest concentrations of egg laying in the last few days of her life.
Fleas eggs are not sticky and usually fall to the ground immediately after being laid, making them distinct from the eggs of many other parasites. If the environment is too cold the eggs will perish before hatching, if conditions are optimal a flea egg will hatch into larvae within 1 to 12 days.
Because the eggs laid by a female flea will normally fall straight off the host the flea larvae with hatch away from the host animal. Flea larvae complete three larval instars (stages) and will range in length from approximately 3 to 5.2 mm long, depending on their environment.
The larvae do not have any eyes or legs, with a maggot-like body that is a semitransparent white colour, that turns gradually darkens as the larvae feeds on feces excreted by the adult fleas. Other than feces, larvae will feed on various types of organic matter such as food particles, dead skin, dead insects and feathers. Flea larvae do not take a blood meal directly from a host, unlike adult fleas.
Once hatched the larvae will seek out a shaded location to spend the next 4-18 days developing such as inside carpets, pet bedding or protected locations under and in furniture or cracks in the floor. If outside larvae again will search for a cool, shaded area such as crawl spaces. The survival of the larvae is dependant on humidity and temperature. Humidity less than 45-50% or the soil temperature is greater that 35 degrees Celsius will cause fatal dehydration to the flea larvae. As long as the environments humidity and temperature conditions permit fleas will develop all year round.
At the end of the larvae stage the flea larvae will spin a silken cocoon and then enter the pupal stage. Fleas in the pupal stage will become adults more rapidly in the warm environments with high levels of humidity. This stage may be complete within three days, or adult emergence can be delayed several months until a suitable host is present resulting in the pupal stage lasting as long as one year.
Controlling flea larvae usually involves using vacuums to remove them from their hiding places, combined with the use of insect growth regulators and dust formulations that cause dehydration of the larvae.
As soon as the adult fleas emerges from the pupal stage it will begin searching for food, during this search phase the flea will remain stationary until a suitable host is located. The flea will then take advantage of its well-known jumping abilities to gain contact with a host. 48 hours after her first blood meal the female flea will begin laying eggs, thus commencing the life cycle again.