Fleas undergo complete metamorphosis. The life cycle, or stages, of the flea is composed of the egg, larval, pupae and adult stages. Cycle length ranges from several weeks to several months and is largely dependent upon environmental conditions.

Fleas feed on the blood of the warm-blooded animals. The adult female has to suck blood in order to be able to lay eggs, and in several weeks that she usually stays on a host, she will suck its blood two or three times, and lay several hundred eggs over her life span – that’s about 20-30 eggs every day. She only needs to mate once in her lifetime to reproduce.

The entire cycle, from egg to adult flea, is complete in 12 – 22 days when temperature and humidity conditions are ideal, but more commonly takes 3 – 4 weeks. Surprisingly, only approximately 5% of a flea infestation is made up of adult fleas on your pet, whereas 95% is in your home as eggs, larvae and pupae.

Although fleas may stay alive for an entire year, it’s rare and their life cycle usually takes in average no more than six weeks. During that time, they pass through 4 stages, and, since adult fleas (the ones that bite) make only about 5% of the entire flea population, an effective fight against flea infestation and flea bites will aim to interrupt their life cycle. Here is a schematic Diagram showing the life cycle of Fleas.



Flea eggs

They develop best in an environment that is warm and humid, and, because they are very smooth, they fall from the host animal and end up on the floor, in the carpet or anywhere in the host’s habitat. They hatch between 6-10 days.

Flea larvae

Larvae hide in dark, sheltered places like carpets and splits in wooden parket. They live of the organic debris – dead skin cells, crumbles or feces from adult fleas. They mind extreme temperatures and light. 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. The flea’s larval stage is completed within about 4-18 days.

After two to three weeks begins the development to adult flea in the silk cocoon that larva spins. The pupa can remain dormant for long periods, even for several months, until they percept a favorable trigger in the environment, like a raise in temperature, vibrations or change in light pattern, anything that will suggest that there’s a meal passing by. Then, within seconds, they crawl out of the cocoon and jump to the host.

Adult flea

Once it feeds for the first time – and leaves those wretched flea bites on our pets or on us – a flea undergoes a metabolic change which turns it into an obligate parasite, meaning it will need regularly new meals to survive. Fleas pierce the skin of their host with their mouth, and then inject saliva to prevent blood from clotting, and their saliva is what can trigger allergic reactions in some animals. They can consume about 15 times their own body weight of blood daily.

There are over 2,000 species of fleas in the world! About 200 species live in the US, three of them are likely to bite humans, and only one is almost guaranteed to be the guest in your house, on your pet or on you. The last ones are cat fleas, or Ctenocephalides felis – this is one of the most widespread species of flea on the planet.

The other two that might feast on you are dog fleas, or Ctenocephalides canis, and human flea, Pulex Irritans – the last one, ironically, is the least probable to meet you.

Fleas are bloodsucking insects, and we usually inquire about them when we need to get rid of them. But they aren’t that easy to eliminate, and next to impossible to prevent; so learning a bit about them, their life cycle and their eating and breeding habits can help us speed up the process and make it more efficient. Let’s start with the basics.

Do fleas fly? A tiny lesson on flea morphology

No, they don’t. But they jump like crazy.

Fleas are small insects, usually about 1/16 to 1/8 inch. Their dark reddish-brown bodies are flattened side to side which makes them very thin, and enables them to easily run through the fur. Only the oldest species, the snow flea, still has wings, but the fleas in general have developed extremely long hind legs which allow them to jump up to 200 times they own length. Jumping is the biological imperative for them, because it enables them to move from host to host fast, or from environment onto the host.

Their bodies are polished and hard, and it’s almost impossible to kill the flea by simply putting it between two fingers and squeezing. They are covered with many hairs and short spines directed backward that allow them to hold on to the hairs of the host, making it difficult to the infested pets to scratch the fleas out of their body.

Now that you know the basics, you can read further about how to get rid of fleas in your house.

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