The Most Common Types of Fleas

Finding fleas in the fur of your cat or dog can be distressing, to say the least. Fleas have earned themselves an unpleasant reputation thanks to their role in the spread of diseases (most notably, plague), and are non-one’s favorite insect. These biting, jumping bugs can quickly multiply and spread throughout your home so, if you find them hopping through the coat of your pet, you need to act quickly to eradicate them.
But what are the most common flea species, and how can you tell them apart?

How many species of fleas are there?

Fleas are one of the world’s most prevalent parasites, with over 2500 species and subspecies known to exist around the globe. But what are the different types of fleas you’re most likely to encounter, and how can you tell them apart?

Most common flea species

The cat flea (Ctenocephalides felis)

The cat flea is the most common of all domestic flea species and is especially prevalent in North America. Despite the name, the cat flea can be found in the fur of both felines and canines and will also occasionally bite nearby humans.


The tiny cat flea measures between 1 and 3 mm in size and is reddish-brown in color. These wingless insects have a flattened body and powerful hind legs, for an impressive jump.

a closeup of the cat flea

7th Son Studio/


Cat fleas have a short lifespan but a lightning-fast reproductive rate, with adult females laying up to one egg every hour. The eggs of the cat flea are tiny (up to 0.5mm in length), white in color and oval in shape. Their smooth, dry surface means they can easily fall out of your animal’s fur to land on carpets and furnishings around your home, where they eventually hatch into larvae.


The cat flea is a worldwide pest but is most commonly found in North America.

Dog fleas (Ctenocephalides canis)

The dog flea is not picky about its host and feeds on many mammalian species, including dogs, cats, rabbits, rats, foxes, woodchucks and humans. Though dog fleas are known to exist in the United States, they are far more commonly found in Europe.


Dog fleas and cat fleas look almost identical to the naked eye; both measure up to 2 mm in length, are wingless and reddish-brown in color. The minute differences between these two species can only be observed under a microscope, where the dog flea can be seen to have a more rounded head and more ‘teeth’ on its legs than the cat flea.

dog flea closeup

Jiri Prochazka/


An adult female dog flea can produce hundreds of eggs in her lifetime, which typically lasts between two and four weeks. Dog fleas lay these eggs continuously while living in the fur of their host (where they usually stay for the duration of their lifetime). These eggs are white and oval in shape and measure up to 0.5 mm long. Being smooth and dry(like cat flea eggs) these then drop from the coat of your pet onto other surfaces around your home.


The dog flea can be found worldwide and is the most prominent flea species in many European countries including Ireland, Greece and Hungary. Dog fleas are also found in the United States, especially in more northern regions, though they are far less predominant than the cat flea.

Human fleas (Pulex irritans)

The human flea is another global species that primarily parasitizes larger carnivores – including humans. They are more common in North America than dog fleas and are an itchy nuisance for those who encounter them. Aside from being annoying, the bites of the human flea can transmit parasites and diseases such as tapeworm and typhus. Pulex irritans is also the species responsible for transmitting the deadly plague bacteria, Yersinia pestis, which devastated populations around the world throughout history.


Like most flea species, human fleas are reddish-brown in color and wingless, with a laterally flattened body They grow up to 4 mm long, which is slightly larger than cat and dog fleas.

closeup of human flea

Cosmin Manci/


The lifecycle of the human flea is similar to that of most other flea species. These fleas breed best in barns and stables, where manure and debris keep the eggs warm and moist when they fall to the floor. Human fleas have a long lifespan compared to most flea species and can live up to 2 years. They lay eggs throughout the year, which typically hatch within 4 – 6 days.


Human fleas are found all over the world, including North America.

How can you tell the most common flea species apart?

Cat fleas are very similar in appearance to dog and human fleas; in fact, you’d need a microscope to spot the difference. Telling them apart is, however, pretty easy, as dog fleas are far more common in Europe. If you live in the USA and your pet has fleas, they’re almost certainly cat fleas – though you can ask a veterinarian if you’re still unsure!

Human fleas also look very similar to cat and dog fleas. However, they are slightly larger and reach up to 4 mm long, whereas cat and dog fleas rarely grow larger than 2 mm.

Other common flea species

Other common species of flea include the Northern Rat Flea, the Oriental Rat Flea, the Rabbit Flea, Stick tight fleas (aka Hen fleas) and the Squirrel flea.

Though these fleas will feed off domestic cats and dogs (and humans) if necessary, they are more commonly found on other animals. As their names suggest, these fleas favor rats, chickens, rabbits and squirrels as their hosts. However, this doesn’t mean they can’t bite you and your beloved pets, so check your animals carefully if they encounter wild animals.


Fleas are one of the Earth’s most common pests, with over 2500 species described worldwide. Despite their diversity, most flea species look very much alike – so how can you tell them apart? The differences between dog, cat and human fleas are so minute that they’re largely unnoticeable to the naked eye. However, the clue to their identity is often in their location. Dog fleas are common in Europe, but far less prevalent in North America. If you live in the US, your pet is most likely to have cat fleas. Human fleas are larger than most and more commonly found on larger mammals.


Rick Hammer

There’s 2 kinds of bugs on my room mate’s body and matters one is on hia head that seems to havw no head or tail (got picture in phone) the other seem to live on hia bed and body and can be seen with


    Is it possible your friend is dealing with lice on the head and bed bugs or fleas in the bed and on the body? Those would be my first guesses, based on the locations you’ve mentioned.

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