What Do Fleas Look Like?

​​What Does A Flea Look Like?

Having the knowledge on what fleas look like will help you recognize if you have a flea problem. Fleas are small insects which do not have wings. They live on cats, dogs and birds as well as other wild animals. They survive on a diet of blood from their host, and by reproducing. Fleas form the order called Siphonaptera.

Find out more on how to identify fleas so you can prevent an infestation.

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what do fleas look like

Cat Flea - CC Image courtesy of Clay Nichols

There are more than 2000 different types of fleas found all over the world. Although there are many types of fleas, most of them have the same characteristics. The most common ones are cat and dog fleas. Despite being called cat and dog fleas, it is possible to also find them on birds and other furry mammals.

Flea On Skin

Flea On Skin - CC Image courtesy of Charley Eiseman

How Big Are Fleas?

Like all living things, a flea goes through various development stages. In comparison to other insects, the life cycle of a flea is not long. Depending on conditions the life cycle may take two to three weeks or up to several months. In ideal situations, adult cat and dog fleas may live up to a year. But, without a host, they will only survive one to two weeks.

The size of an adult flea can be anywhere between 1.5 to 3.2 mm in length. The average female is 2.5 mm in length and they are bigger than the males with larger and heavier abdomens.

Flea - to scale

Engorged Flea

Engorged Flea - CC Image courtesy of Ryan Eide

Once they become an adult flea their size is fixed. Further growth only happens during the first blood meal.

A flea on human skin

A flea on human thumb

They will reach their maximum size within 48 hours of feeding. Females may increase by 140% in weight, whereas males will only be around 19%.

Flea Eggs

A female can only reproduce after her first blood meal from the host. Around 36 - 48 hours after this blood meal the adult female will lay her eggs. The eggs are white and smaller than a grain of sand.

flea eggs

She will lay the eggs in the host’s fur in bunches of approximately 25 eggs. An adult female is capable of laying about 50 eggs per day. During her lifetime it is possible she will lay over a 1000 eggs.

Flea Egg

Flea Egg - CC Image courtesy of Russ Crutcher

As the eggs are not attached when the animal moves, they will fall off. They are then distributed throughout the environment, which in my opinion can be a good or bad thing depending on where they land. The eggs take from two days to two weeks to develop. They will only hatch when the environmental conditions are right for them. If it is cold, the hatching could take longer but if it is warm and humid, they hatch faster.

Flea Eggs On Carpet

Flea eggs in the carpet - CC Image courtesy of Denni Schnapp

Flea eggs between carpet fibers

As the eggs hatch, larvae emerge, and so begins the next stage of life.

Flea Larvae

Flea larvae make up around one third of the flea population in a home. As the larvae emerge from the eggs, they are blind. Larvae will avoid being in the light and bury themselves deep in carpets and crevices.

Flea Larvae

Flea Larvae - CC Image courtesy of Peter J Bryant

Over several weeks they will begin to develop. To aid their development, they will eat flea dirt; pre-digested blood passed by adult fleas. Flea larvae cannot survive solely on flea dirt. They will also consume conspecific eggs, both non-viable and fertile ones.

3rd Instar Cat Flea Larva

3rd Instar Cat Flea Larva

Flea larvae can be up to a quarter inch long and are white (almost transparent) with pale hairs and they have no legs.

Flea Larva

Flea Larva - to scale

If conditions are right, the larvae will begin to shed their skin and spin cocoons. This will happen within around five to twenty days of hatching. This leads to the next stage in their life the pupae stage.

Shed flea larvae casings

Shed flea larvae casings

Flea Pupae

This is the last stage of development. At this stage, the pupae closely resemble the adults. They start out white then turn yellow before finally turning brown.

Flea Cocoon

Flea Encased In A Clear Cocoon (Pupae)

Once the cocoon is formed, the larvae molt, and after around two to three days they become pupae. The pupae are protected by the cocoon. It can be anywhere from several days to weeks until the adult flea emerges. In some instance, the pupae will develop without an external cocoon.

naked flea pupa no cocoon

Flea Pupae with no external cocoon

If the environment is not right for the adult flea to emerge, the cocoon is capable of protecting it for months.

The cocoons have a sticky outer coating allowing them to lay undetected deep in carpets. The flea will stay inside the cocoon until it feels the obvious presence of a potential host. The pupae will observe for body heat, a rise in carbon dioxide levels and vibrations. These are signs triggered by pets or people moving around. Only then will it be alerted to emerge from its cocoon and begin its life as an adult flea.

Flea Pupae

Flea Cocoons - CC Image courtesy of Sean McCann

Adult Flea

As soon as it emerges from the cocoon the now adult flea must begin to feed within a few hours, so needs to find a host. After their first meal adult fleas will begin to breed and will start to lay eggs within a few days.

New adult fleas are flat-bodied, very small, and almost black in color. Once they begin to feed, they will become larger and lighter in color.

Flea Overhead View

Unfed flea - CC Image courtesy of Lynette Elliott

A Feeding Flea

An Engorged Flea

When fleas are newly emerged, their abdominal segments overlap making them seem smaller than they actually are. After feeding these spread out and no longer overlap. When they have consumed a blood meal, their abdomens expand and their size is doubled.

They will spend most of their time living on the host, feeding (bloodsucking), breeding, and laying eggs.

What Shape Are Fleas?

Like most insects, they have six legs and three body segments; head, thorax and abdomen. The body is a flattened pancake-like shape, which allows them ease of movement through the fur or feathers of the host. They have two black eyes, one at either side of the head.

Their body is covered with dark spines and bristles. On their legs, they have backward shaped hairs and spines, giving them the power to grasp on to the animals.

Flea

Flea

They have long legs; the hind legs being longer than the others. This helps them with their amazing ability to jump from host to host. Fleas do not fly.

Flea

CC Image courtesy of Clay Nichols

What Color Are Fleas?

Fleas have a durable exoskeleton which is hard to rupture. The outer cuticle surface has a pattern of wavy striations.

Fleas have a glossy sheen to their body. This comes from the epidermal gland secreting an oil-like substance. Once secreted onto the cuticle it allows the flea to glide more easily through the host’s hair.

Adult fleas are usually a dark brown colour. But you could also see fleas which are light brown, reddish brown or black, I’ve seen a variety of colors in my time.

Side-On Flea

CC Image courtesy of Lynette Elliott

Newly emerged adult fleas are darker than other already engorged fleas. Once they make a start on feeding their abdomens spread out and they become lighter like other fleas.

What Do Fleas Look Like Once They’ve Fed?

Once they have taken a blood meal from their host, the color of the flea will change to a reddish black color. Once engorged on its blood meal it will be nearly double its weight and size.

Cat Flea

Cat Flea - CC Image courtesy of Clay Nichols

If it is a newly emerged flea, it will be almost black in colour. After it takes its first blood meal, the abdominal sections will no longer overlap and the size of the abdomen will double. This makes it now look lighter in color.

Females are already bigger than males and have larger and heavier abdomens.

What Do Flea Eggs Look Like?

After taking a blood meal, the female flea is able to reproduce and will lay her eggs on the host. She will lay her eggs in bunches of around 25 eggs.

The eggs are tiny, white, and oval shaped. Flea dirt, which is the accumulation of small black specs often seen on animals, is often mistaken for eggs. In fact, this is instead primarily made up of flea excrement, which mostly consists of the blood that the flea has taken from a previous host.

flea dirt on dog

Flea dirt on a dog's underbelly

What Other Bugs Look Like Fleas?

Bed Bugs

People often mistake bed bugs and ticks for fleas. Knowing the difference will help you deal with the infestation as appropriate.

Bed bugs do not fly or jump so you will only find them crawling.

They are a reddish brown color with a flat seed shaped body and are around 1.5mm to 5mm in size. Bed bugs are nocturnal insects. You’re more likely to find these on your bed base or the piping of your mattress digesting their meals.

Bed Bug Vs Flea

Bed Bug Vs Flea

Ticks

As it has eight legs, a tick is considered part of the arachnid family and is a reddish brown colour. Ticks do not jump or fly and rely solely on crawling around. They are bigger than fleas and can measure up to 6mm.

Tick biting dog
Tick vs bed bug

Springtail

Another insect which may be mistaken for a flea is a springtail. Often mistaken for a flea as it is also a flightless insect which jumps around. This one, however, will not bite, sting or cause damage. They like to live in moist areas so if you are seeing these in your home it could mean you have a damp issue.

Springtail

Springtail

Other

There are a couple of other ones which deserve a quick mention as I’ve seen people confuse them with fleas in the past. These are the black carpet beetle and flour beetles. This is often due to the similar colour and size. These insects are only capable of crawling and not jumping. They are generally found in carpets, dried foods and textiles.

Carpet Beetle

Carpet Beetle

What Do You Do If You’re Unable to Identify a Possible Flea?

If you think you have a flea infestation but you’re not quite sure, there are a number of things you can look out for helping you determine if it is a flea problem or not.

Check out some pictures of fleas like the ones in this article and compare them to the insects and signs you've spotted. Use the information above to help you decide if you have a flea infestation or not.

fleas on cats stomach

Fleas on cats stomach

Dog Fleas

Dog fleas on a flea comb

Flea bites on human

Flea bites on a human leg

If you have pets, you need to observe and see if they are scratching more than usual.

If they are and they are licking and biting themselves, this is a sure fire sign of a flea infestation.

Check your pets; use a flea comb to go through their fur and look for fleas. Chances are you won’t find any fleas as they move too fast. If there are fleas you will find flea dirt, which is the faeces of fleas and will be observed as tiny black specs.

flea dirt on cats

Flea dirt on a cat

If you’re still not sure, touch the flea dirt with a wet tissue or add a couple of drops of water to it. If you see it diluting into a red liquid, then it’s definitely flea dirt. Flea dirt is faeces and is the waste blood excreted by the flea.

If you have seen insects hopping around your carpets or drapery this could be a sign. Put on a white pair of socks and shuffle around your carpet. If you notice black specs on your socks, these are likely to be fleas hitching a ride.

The darker and more moist areas of your yard are likely to be a perfect hiding place for fleas. You can try the white socks trick here too to find out.

If you’re still not sure if you are dealing with fleas you need to call in the experts. They will determine if the infestation is fleas or not and can then provide you with the right solution.

Summary

Having now read all the information above it gives you a better understanding of what fleas look like. I have taken you through the life cycle of a flea from eggs through to larvae, pupae and to adulthood. Each section has provided you with descriptions of what to look for during each stage of the life cycle. You should now be more knowledgeable about the color, shape and size of fleas both before and after feeding.

I informed you of other insects commonly mistaken for fleas and how to spot the differences. Hopefully, I have equipped you with guidance to help you know what to do if unable to identify a possible flea. Remember to seek professional help if you remain unsure. This will help you to ensure the problem is tackled appropriately.

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