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Last updated date: 18th Apr 2024
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What are Fleas?

The Flea animal which belongs to the Arthropoda phylum and class Insecta is also called flea insect. The scientists that expertise in insects are called Entomologists. This insect of an animal is of the order Siphonaptera and popularly referred to as flea. The word Siphonaptera in Greek means wingless(Aptera) tube (Siphon). The flea is a small insect about one-eighth of an inch in length with no wings. Flea is a parasite that attaches to its host on the exterior region and hence called ectoparasitic. The flea animal thrives by consuming the blood of their hosts, also called bloodsucking animals. Even without wings, they are not easy to dislodge from their attached hosts due to their strong claws. Now that we have understood what are fleas origin and their classification in the animal kingdom. Let us get a better understanding of what are fleas through their characteristics, behaviour, life cycle, the flea meaning and their relationship with the hosts and humans included.

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History of Flea Animal

The flea animal was first identified and distinguished by the Swedish Naturalist Carl Linneaus between 1735 and 1758 when he was identifying insects. With the distinct feature of no wings, it was classified as “Aptera” which means wingless. Much later in the year 1810, a French zoologist Pierre André Latreille redid the classification of insects differentiating them into three parts on the basis of wings and their mouthparts. The three parts included Thysanura commonly known as silverfish, Anoplura commonly known as sucking lice and Siphonaptera commonly known as fleas. The oldest fossils of the flea insect were found from the middle of the Jurassic period to the early crustaceans period. After which its historical genesis was found in Gondwana’s continental area and has been tracing its journey northwards from there. The flea insect most likely later evolved along with other mammal hosts and followed with it like the birds. The flea insect was an essential link as the chief agent transmitting the Black Death (bubonic plague) in the Middle Ages, in the chain of events that resulted in the death of a quarter of the population of Europe. Only 2000 of the flea species and subspecies are known and makes the flea insect relatively a smaller group in order of insects and entomologists suggest there are many more waiting to be discovered and studied.

Characteristic Features and Behaviour of Flea




Dark and Reddish Brown 

Number of Legs 

6 (The flea hind legs makes it the best jumpers)




0.1 to 0.32 cm (0.039 to 0.13 inch) 



Natural Habitat 

In polar, temperate, and tropical regions native species of fleas are found. 

Thrives On

Rely and live on any warm-blooded animal. They prefer to live on opossums, rats and other rodents, dogs and cats, and for a while on humans as well. They can also be found on non-living and inanimate objects like fabrics, carpets, blankets, and shoes.

  • Their compressed and flat bodies make it easier for them to carry on and move around easily with easy movements through the hairs or feathers on the host's body.

  • Fleas, unlike other insects, do not possess compound eyes. Instead, the flea insect only has simple eyespots with a single biconvex lens.

  • Hard plates called sclerites that possess many hairs and short spines which are directed backwards cover the entire flea body.

  • The movements on the host are also assisted by these sclerites.

  • The sclerites make the body hard that helps it withstand great pressure and helps them adapt and survive by eliminating dangers.

  • The flea does not fly but it can jump high up to 18 cm (7 in) vertically and up to 33 cm (13 in)horizontally. 

  • The flea exceeds the capabilities of muscle when jumping because of the rapidity. Flea’s store muscle energy in a pad of the elastic protein named resilin and instead of relying on direct muscle power, they utilize resilin before releasing it rapidly like a bow from the arrow, first a little backward and then propelling forward. 

  • The adult flea feeds on the fresh blood only.

Flea Development and Life Cycle

The flea develops naturally through a cycle that is common for insects in four stages, egg, larvae, pupa, and adult. The adult Flea lays eggs when it lives in a feathery and furry environment like a dog and a cat which is an ideal place to reproduce. Depending mainly on temperature and humidity the life cycle of a flea can be completed in as little as 14 days or be prolonged up to 140 days and a single flea could lay upwards of 2000 eggs in her lifetime. One percent of the entire population of the adult can be found in the home environment while many are preparing to hatch on the host as many live in various stages of their life cycle lurking around.

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Stage 1- Egg

  • The batch sizes of the eggs laid after the maturation of the ovaries in female fleas as they suck on fresh blood and copulate with the male fleas range from few hundreds to thousands. 

  • The eggs laid attach onto the host, most probably the furry animal and if there is any movement it tends to easily fall off so the best place to keep it safe is where the host usually lies on their resting space or a yard. 

  • The gestation period is not very long and as the eggs are laid the female flea hatches onto them for the first 2-5 days and larvae start growing. And in some cases, it may take up to 10 days for the larvae to emerge.

Stage 2- Larvae

  • As the larvae are formed only when the egg hatches at an ideal stage of development with the right amount of humidity, warmth, and optimum temperature.

  • This stage in the life cycle lasts from 5 to 11 days after which the larvae enter the pre-adult stage of pupae.

  • They are blind and avoid sunlight and keep to themselves in the dark. 

  • Humid places such as sand or soil are the right place for them to grow. The larvae are also grown on cracks and crevices and under the carpets and even on the bedding.

  • The larvae feed off on the dirt in the environment they are growing and even on the organic matter, which includes the faeces of the furry animal.

Stage 3- Pupae

  • This is the pre-adult stage that lasts from 7 days to 14 days.

  • The larvae turn and as it spins and the cocoon is released giving rise to the pupae.

  • The cocoon if not released can be a dormant stage that lasts from few weeks to six months under adverse conditions.

  • Within the cocoon, the larva molts and undergoes metamorphosis for a final time into adult form.

  • The presence of a suitable warm-blooded host and increased carbon dioxide levels can trigger the emergence of the adult form of flea and hatch to the host.  

Stage 4- Adult

  • Even in a flea-free environment where pupae are already present with the presence of a suitable host a mass-emergence of adult fleas may occur.

  • The life of an adult flea is only 2-3 months be it male or female. 

  • The life span can be lesser than the actual period especially if they do not find any fresh blood to feed on, as that is the primary goal of a female adult flea so as to start reproducing as soon as possible.   

  • Under optimum temperature, food supply, and humidity which are the ideal conditions the adults have a chance of living up to 6 months to a year. 

  • If the adult thrives in optimal and desired conditions the female flea in their lifetime can lay up to 5000 eggs. 

  • Once again the life cycle starts when the adults mate after the female’s ovaries have matured and the life cycle continues.  

Flee Animal Relationship With The Host

  • The flea has the ability to change its host at any point in time if they are not able to reproduce.

  • There are many hosts that the flea as a parasite feeds on like dogs, cats, squirrels, rabbits, ferrets, rats, mice, birds, and humans. 

  • The flea feeds off of many hosts, not every host provides an optimum environment for the flea to reproduce.

  • As the size of the host species decreases the host specificity also decreases.

  • On humans especially and many other hosts the flea can cause a nuisance by creating an itching sensation and when the host responds by biting and scratching it leads to infections caused by fleabites.

  • The flea bite is similar to a mosquito bite where the nodule of the epidermis is irritated at the site of the bite and leads to raised, red, and swollen skin. This is also called flea allergy dermatitis which is caused by eczematous itchy skin.

  • In extreme cases, flea bites can also result in loss of hair and even anaemia in the hosts.

  • There are many home remedies that humans follow to get rid of the flea bite and many are effective and if not they can easily consult a doctor.

  • Even if the pet has brought the flea into the house the flea tends to lurk around in various areas of the home once reproduction starts. Therefore, it is important to disinfect the house and also take your pet to the vet doctors as the severity of the reactions cannot be predicted.

  • For a long time, the flea has acted as a vector and carrier of many diseases and has been the reason for many plagues, especially around Europe like the bubonic plague. 

  • During the second world war the fleas were infested with Y. pestis in China which was utilized as biological weapons due to their vector quality.

  • The septicaemic plague was also a result of using the flea as a weapon, whenever this method is adopted to attack during a war it is called bioterrorism and the flea has played a major part in such scenarios in the history of the world.

Flea Treatment

  • Apart from the homemade solutions by the common man, there are multiple countries that try to control flea infestation and infection via pest control. 

  • Approximately $2.8 billion is spent annually on flea-related veterinary bills in the United States alone. 

  • Among the pet groomers another $1.6 billion annually for flea treatment for the furry animals’ safety. 

  • The estimated amount spent on the prescribed flea treatment is around four billion dollars.

  • Pest control is the most common method adopted for treatment and also impacts economically with around 348 million dollars being spent. 

Interesting Facts About Flee Animal

  • The flea as known to be the best jumpers only second to the frogs at once can jump over 30 thousand times in a row.

  • Capable of lifting 150 times the weight of their own body.

  • Within the first week of turning an adult from pupae, if they fail to fulfil their goal of finding blood, they die after the 7th day regardless of the optimal environment they live in.

  • Until their first meal of fresh blood, the females are incapable of laying eggs.

  •  The female flea on a daily basis can consume blood fifteen times their own body weight.

  • After their first meal within the next 35 to 48 hours, females lay eggs as their ovaries mature and gestation is shorter.

  • The flea animal can jump so high that its ability in a human can be considered to be able to jump over the Eiffel Tower.

  • Largest carriers of plagues and due to fleas and the consequential outbreaks up to 200 million people across Europe between 1346 and 1671 were killed. 

  • The Black Death pandemic likely killed over a third of the population of Europe between 1346 and 1353 which was also initiated using the flea animal as a medium of weapon.

  • In the nineteenth century, flea circuses were held and were extremely popular as an entertainment medium for the audiences.

  • The circus in Europe in the 1830s was organized and completely orchestrated by the jewellers and watchmakers who tried to show their skills by featuring the flea insect dressed as miniature carts or chariots that towed humans and also portrayed the role of rollers and cannons. 

  • The fleas that choose the rats and mice as their host are the main carriers of diseases that result in plagues. 

  • The poop of an adult flea is blood.


From this article, we have understood the flea meaning. The skinny skilled jumpers that are the fleas have time and again evolved from being entertainers to humans in the 19th century to being plague carriers over time. There are many ways fleas find to enter houses and infest the surroundings. Even without a cat in one home the cat fleas are more common and their way of affecting the host may or may not be severe depending on the time one has ignored the signs. Flea growth must be controlled through pest control as much as possible for the sake of everyone’s health and safety.

FAQs on Flea

Q.1) Are Fleas Risky for Humans?

Ans.) Fleas are harmful to both humans and non-humans. The fleas mainly feed on non-human animals because of their furry nature where they grow but flea insects can bite and infect humans. Once they enter your home they can be difficult to remove if they go unnoticed because even though they need a host to feed on and reproduce they can survive for more than 100 days without a host. Humans are affected by fleabites and they can trigger allergic reactions. The effects of this will not often have a serious impact on a person's health but they need to be treated as soon as possible so it does not spread to other areas.

Q.2)  How to Keep the Home Clean from Fleas?

Ans.) There are many ways to keep your home flea free and you can do it in very simple ways too. The most common one being dish soap. It involves creating a flea trap using dish soap and also using herbal flea spray and even a lemon spray to get rid of them from your home. Baking soda, Salt, Diatomaceous earth, which are basically the microscopic remains of the fossilized algae, diatoms and is a powder form of a substance that is non-toxic to humans. The other very effective ways are using Rosemary and planting Flea repelling plants.

Q.3) Do Fleas Live on Humans?

Ans.) Living on humans will require the fleas to feed and reproduce while being in contact with the humans which is highly unlikely because humans lack substantial hair like animals. And without the protection of fur or feathers, it's very difficult to reproduce. A lab study observed that for the flea to have a chance to lay viable eggs the flea insect would have to feed on a human for 12 straight hours which has high chances of not coming true as they can be detected and gotten rid of.

Q.4) How Do You Know the Flea Insect has Entered My House?

Ans.) If you have a pet like a dog or a cat which are furry animals then there are high chances of the animals who carry the fleas inside your house. So the best way is to take them for a walk in cleaner spaces. The fleas usually look smaller and can be unrecognizable and keep hygiene at all times in all the corners of the home. If you have a flea bite and more members at home are showing allergic reactions then they might be laying eggs on the fabrics of the sheets and mattress, inspection and proper disinfection are recommended in such a case.