Flea infestation is a common problem that pet owners have to deal with on a regular basis. These little bugs infest the fur and skin of your pets, disrupting their comfort and also posing a significant threat to their health. 

They also make the life of pet owners uneasy; this is due to the constant scratching of pets, and the trail of fur they leave on your carpets
and floors. 

It is therefore important to get rid of such fleas. Knowledge about fleas; what they look like, their life cycle, common breeding areas, and conditions could come in handy in helping you deal with them. 

A deep understanding of their life cycle will help you make stage-targeted interventions, and thus control flea breeding and infestation in your household.

The flea life cycle


There are over 2000 different species of fleas in the world. The most common ones in the USA are the dog flea, Ctenocephalides canis, and cat flea Ctenocephalides felis. Both species can infect either dogs or cats, and sometimes birds too.

They share a common life cycle that has 4 stages:

  1. - Eggs
  2. - Larvae
  3. - Pupae (in cocoons)
  4. - Adult

Over 95% of fleas exist in the premature forms; that is eggs larvae and pupae. Only 5% live as adults. Every stage has its own unique properties and requires different factors for survival.

These factors also influence how fast the flea can move from one stage to the other. Under optimum conditions, the entire cycle can be completed in 12 to 21 days. 

However, the average duration is often 3-4weeks in the USA. In extremely harsh conditions, it can take over a year to complete the cycle.

Below is a detailed description of each stage in the life cycle of a flea:

Flea eggs


This is where it all begins; in the form of eggs.

Laying of eggs

Adult female fleas lay eggs throughout their adult life.

They typically lay eggs 36-48hours after feeding on a blood meal, that is your pet's blood. 

The eggs, therefore, fall on the pet's skin and fur. The number of eggs usually varies. A mature flea lays about 20 eggs after a single feed. They can, therefore, lay over 50 eggs in a single day.

Properties of flea eggs:

To the naked eye, a flea egg appears as a small whitish object. A closer look at it reveals the following characteristics: each egg is about 0.5 mm in diameter. 

This is small enough to be hardly visible to an unsuspecting eye. 

They are oval in shape and have a pearl white color. Given that they are often laid in clusters, they will appear as a whitish substance on your pet's skin, between the fur lines.

Unlike eggs of other pests such as ticks and lice, flea eggs are not sticky. They, therefore, do not last for long on your pet's skin but fall off into its environment.

A common question is whether there is a difference between flea eggs and dandruff. The answer is they are not the same. 

Dandruff is made of dead skin cells that are being shed off. They are commonly caused by fungal infections on your pet's skin.

Where do you find flea eggs?

Where do you find flea eggs?

As already stated, flea eggs are not sticky. They, therefore, fall off whenever your dog or cat scratches itself or shakes its body, or as it moves around. 

The common locations for flea eggs include carpets, especially those with long fibers, beddings if you let your pet sleep in your bed, grass in the yard, warm soil, and other areas that your pet frequently plays around.

Conditions that are favorable for flea eggs:

Flea eggs thrive in warm and humid environment. That's why
they are found in specific locations, despite falling off on virtually every surface.

Surfaces such as carpets and grass serve as insulating materials that create a microclimate that favors egg survival.

The eggs need a temperature of at least 55 degrees Fahrenheit to grow and mature.

Humidity is not as important at this stage as warmth is. The need for warmth explains why flea season often coincides
with summer and lasts for longer periods in the southern states.

Viability and survival of flea eggs:

Flea eggs take anywhere from 1 to 12days to mature into larvae stage. The determining factor here is largely temperature, with lower temperatures requiring a longer duration for maturity. 

In terms of viability, eggs subjected to harsh condition won't hatch but will go dormant. These eggs will remain viable for a few weeks before dying off.

Harsh conditions may kill flea eggs and render them unviable. Temperatures below 50 degrees or above 101 degrees will render eggs unviable.

Low humidity, below 45%, is also unfavorable for the survival of flea eggs.

How to kill flea eggs?

You first need to identify the areas that are likely harboring these eggs. Look in areas your pet sleeps or plays around. 

You can then select a treatment method that is effective against eggs. For in-house elimination, powerful vacuum cleaners can suck the eggs right off your carpet's fibers.

You should consider replacing your carpet if your vacuum cleaner cannot clean it thoroughly. 

As for beddings, washing them using hot water will kill all the eggs as they cannot survive n high temperatures. Other mitigating measures involve extermination in your yard.

Flea larvae

Flea larvae are the next stage in the cycle. They are hatched from mature eggs.

Flea larvae are the next stage in the cycle. They are hatched from mature eggs. 

Unlike their predecessors, they are actually an active stage; they move around, feed, and excrete waste. 

They make up over 35% of the population of fleas. Below are a few details on flea larvae:

Features of flea larvae

Larvae generally resemble maggots. They are quite disgusting
and unappealing to look at. At the time of hatching, they are about 2mm in length. 

They gradually increase in length to about 5mm long, and 0.5mm wide when fully mature. This is almost the size of the tip of a sharpened pencil.

As for color, they are usually almost transparent at the time of hatching. 

They gradually darken as they feed, turning to a dark shed of

Given their minute size, it is common for larvae to be mistaken as black worms. They are however dark red in color.

Developmental Stages of flea larvae

Flea larvae develop through three stages, which are commonly referred to as instars. 

The transition from one instar to the next requires a certain level of growth, before molting. 

Therefore, each larva must undergo two molting phases, each between the three stages, before turning to a pupa.

The different levels are often abbreviated as L1, L2, and L3. Each stage has a different duration, which is often influenced by the larvae's access to food and environmental factors. 

Each stage is however much longer than the preceding one due to increased nutritional requirements and growth targets as the larva gets bigger. 

It takes anywhere between 5 to 20 days for fleas to transition through all the stages. 

Third instars often start spinning of cocoons, which will form its habitat for the next stage.

Where do flea larvae live?

They occupy pretty much the same environment as the eggs.

Very few larvae will be found on your pet's fur. If present, they will appear as dark worm-like creatures. 

A majority of the larvae will, however, be found in your carpet, on grasses, and warm moist soil. 

They will also be found only in dark areas; under tables and beds, on corners and closets, or under flowers and bushes in the outdoors. 

Larvae avoid light

Larvae are extremely photophobic. They completely move away from well-lit areas and thrive in dark environments. 

This is why it is very hard to spot flea larvae, despite them being large enough to be spotted by a naked eye. 

They, therefore, burrow to the roots of carpet fibers, or the deepest part of cracks and crevices on wooden floors and baseboards.

What do flea larvae eat

What do flea larvae eat?

Unlike adult fleas which rely on the host for nutrition, larvae scavenge their environment for nutrition.

They have powerful mandibles and teeth for chewing. 

The larval stage is also the most demanding in terms of nutrition, as the flea has to stock up enough nutrients to last it through its pupae stage.

They also need these nutrients to spin up a cocoon.

The larvae depend on products produced by adult fleas to gain nutrition. It feeds on the feces of adult fleas.

This debris contains undigested blood as the adult's gut absorbs only what it needs and excretes the rest undigested. 

This debris is often available in the same environment that the eggs hatch, so the larvae barely move a foot from the point of their hatching.

Larvae also feed on flea eggs. They, however, don't consume any egg, but conspecific eggs.

These are mostly non-viable eggs and egg chorions. 

Every larva consumes about 7 eggs during this stage. Both the eggs and adult feces are an essential part of their diet.

They must both be present in adequate quantities for the larvae to mature.

Favorable conditions for flea larvae:

Flea larvae require pretty much the same conditions as eggs.
They require a warm and humid environment. The additional factor for larvae is food. 

They need to live in the vicinity of adult fleas as they rely on their debris and eggs for nutrition.

Getting rid of flea larvae:

Larvae are not as easy to eliminate as eggs. They are well hidden in dark places. If it is in carpets, they are at the base of the carpet

Simple vacuuming may not eliminate them in totality. You, therefore, have to use sprays and other treatment methods to get rid of them. 

You should really consider replacing your carpet with one that has very short fibers.

Another alternative is the complete washing of the carpet using hot water. 

This service is provided by extermination companies or home cleaning services. As for outdoor spaces, sprays are very effective.

Flea pupae (flea cocoons)

This is the last developmental stage before attaining full maturity into an adult flea. 

This is the stage in which the immature worm-like state of the flea transforms into its true nature as an insect. 

It is also uniquely a stage that preserves an immature flea in an enclosed and safe environment until the environmental factors favor its release. 

It is, therefore, a stage of preservation and metamorphosis.


This is a protective casing that houses the pupa. It is spun from silky gossamer by the last instars of the larval stage.

They are about 4 to 5mm long and 2mm wide. It appears as a tiny white capsule. They are usually silky white in color at the start. 

But with time, their surfaces gather dust and soil from the surrounding which makes them camouflage.

The pupa stage moves into the cocoon and seals itself in before hibernating. 

The cocoon has several properties that aid in the survival of its pupa:

  1. It is an insulator. Being made of silk, it can maintain its inner temperatures at almost a constant range despite fluctuations in the outer environment
  2. It is thick and tough, protecting the pupa from both mechanical and chemical damage.
  3. The common flea sprays and treatments may be ineffective against the pupa.
  4. It is sticky. Unlike the eggs which freely fell off, cocoons are tough to move. They adhere to carpet fibers, rugs, and even grass.
  5. This way the pup is protected from any attempts of removing or eliminating it.

Where are Pupae live?

The pupal stage is a state of preservation. The fleas in this stage go dormant, and their metabolism is reduced to the bare minimum needed to sustain life. 

They, therefore, do not feed, move, or do anything that a normal insect does. 

They rely on nutritional stores that were stacked up during the larval stage. They can sustain this hibernated state for over a year.

Metamorphosis into adult fleas

Complete maturation to adult fleas takes 8 to 12days under optimal conditions.

The pupa can, however, remain in a dormant state for up to
one year if conditions are favorable. 

This is because the whole point of hibernation is to wait until factors are favorable for the survival of an adult flea. 

These include temperature, humidity, and food availability. The adult will, therefore, come out of the cocoon when the climate is okay, and food availability is clear. 

This is assessed by sensing vibrations and movements around the cocoon, body heat, or carbon dioxide. 

All these indicate the presence of a potential host, which is the source of food.

Adult fleas


These are fully mature fleas. They are the stage that causes all the menace, and probably the reason you are reading this.

They make up about 5% of the total flea population. They emerge from cocoons only when a host is nearby, and quickly infest them as they need to feed within a few hours
in order to survive.

What do adult fleas look like?

An adult flea is a small dark brown insect that can be seen
using your naked eyes. 

It is about 1.5 to 4 mm in length and is flattened on the back and the front. It has a body that is much larger than its head.

Unlike most insects, fleas do not have wings. They, however, have two pairs of front legs for crawling and a powerful hind set that allow them to hop from one spot to the next.

A flea is a simple insect with six legs and a pair of antennae.

The antennae are however tiny and hidden in grooves, making them hard to spot. 

They also have a pair of compound eyes. This does not aid much in vision but serves in differentiating light colored objects from dark-colored objects.

Location of adult fleas

Adult fleas spend most of their time on hosts, with short periods in between hosts. 

During this time, they are mostly found on carpets and grasses. During warm weather, adult fleas spread to cover almost all possible locations that can be visited by hosts: grass fields, parks, the beach, river banks, etc. 

That's why almost every dog is affected by fleas during flea season.

How do fleas move?

The primary mode of movement for fleas is crawling. This is usually achieved using the two pairs of front legs. 

Its hind legs are large and powerful. They enable the flea to hop distances up to 150 times its length. For human beings, this is the equivalent of hoping a distance of 300 yards. 

The hopping movement is reserved for skipping onto hosts.

The infestation of a host involves very tactical movement by
the flea. 

First, it only comes out of its cocoon after sensing body heat or vibrations.

This indicates the presence of a nearby host. The flea then uses its eyes to detect host movement. as a dog, cat, or any other host passes in front of it, it casts a shadow that blocks off light.

Whenever the flea sees a reduction in light, it hops frantically towards the moving object in front of it. 

The other technique involves detection of carbon dioxide and hoping towards its source. These tactics enable the flea to easily land on a host.

Adult fleas Feeding

Adult fleas Feeding

Adult fleas have a lot of nutritional requirements. That's why they aggressively pursue hosts from the moment they get out of their cocoons.

Adult fleas feed exclusively on host blood. They have suckers that are designed solely for this purpose. Before biting the host, they cover the bite site with saliva.

This saliva contains an anticoagulant that prevents the host blood from clotting. It also contains a form of numbing chemical that makes the bite less painful. It is however still an irritating process, and that's why pets often go into scratching frenzies when fleas are

The amount of blood consumed depends on its size and gender.

Females tend to consume more blood. The average amount of blood consumed by a single flea is 0.136mls. 

This may sound insignificant, but compounding it to a population of 200 fleas, it is significant enough to drain a pet's blood reserves.

How long can fleas live without host blood? 4 days is the limit. If the flee cannot get a meal within this duration,
it dies.

Infestation by adult fleas

So how many fleas normally infest a dog or a cat. An average
infestation often involves about 20 fleas. This is the case for both cats and dogs.

However, a major infestation could involve over 300 fleas on a single pet.

This is serious enough to cause iron deficiency anemia, especially for kittens and small puppies.

The lifespan of adult fleas

Infestation by adult fleas

Typically, an adult flea stays for a week or two on your pet's fur. This is largely due to regular grooming which gets rid of the fleas.

Without any sort of grooming, they can easily last for more than six months.

Factors favoring the survival of adult fleas

Adult fleas are much more sensitive to environmental conditions. The most important factor for them is temperature.

They can only thrive between 46 and 95 degrees Fahrenheit. Any deviation from this will most likely result in a fatality.

Humidity is not that important for adults as it is for other flea stages.


It is the duty of every living thing to ensure continuity of its kind by reproduction, and fleas adhere to it. 

They reproduce sexually by mating. This is often done on a host, and commonly after feeding. 

The female fleas then lay close to 20 fertilized eggs about 24hours after a blood meal. The cycle then goes on from this stage.

How to get rid of adult fleas?

Though tough to eliminate, they are the easiest stage to deal with. They are sensitive to both physical techniques such as combing, and chemical treatments such as sprays and pills.

In terms of temperature, hot water is sufficient to achieve full elimination of adult fleas residing on your carpets, floors, and beddings. Outdoor fleas are best dealt with using sprays, or diatomaceous earth powder.

In conclusion,

the full control of fleas requires a multi-stage approach. Dealing with adult fleas only addresses 5% of the problem. Understanding the properties and behavior of fleas in each of the stages in their development will greatly aid in eliminating them. 

Therefore, take a keen look at each stage, and make sure that you cover it every time you treat your pets and homes for fleas.

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