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Flea 1.jpg
Scientific Classification

Infraorder: Pulicomorpha

  • Pulicoidea
  • Malacopsylloidea
  • Vermipsylloidea
  • Coptopsylloidea
  • Ancistropsylloidea

Infraorder: Pygiopsyllomorpha

  • Pygiopsylloidea

Infraorder: Hystrichopsyllomorpha

  • Hystrichopsylloidea
  • Macropsylloidea
  • Stephanocircidoidea

Infraorder: Ceratophyllomorpha

  • Ceratophylloidea

Fleas are any of the species that belong to the taxonomic order Siphonaptera. They are small parasitic insects best known as a pest for the harm it can cause animals. This is because they suck blood from the animals and transmit diseases. Diseases that fleas transmit can be very dangerous, which is a common characteristic of parasites. They have special body structures to suck blood and to live on the animals' body.


Flea anatomy

A flea is divided into three different parts of body. There are a head, thorax, and an abdomen. Most fleas usually have a dark brown colored body. The size of flea is so tiny, it is usually 1/12 inches to 1/6 inches. However, people can recognize the flea easily if they have seen it before even though it is very small.[1] A flea is wingless, so it cannot fly.[2] However, because of its long legs, it can jump about 200 times its length of body. Also the flea has antennae, which are attached to its head, to detect heat, carbon dioxide, and vibrations. The flea's eyes are for notice the changes in the air currents and finding meals.[3]


Unlike most other invertebrates, a flea does not fly. It is wingless.[4] However, instead of using wings for locomotion, it uses its legs for locomotion. The flea has three pairs of legs. These are attached to its thorax. Usually legs are side to side or flattened vertically. These characteristics allow the flea to move easily in hair, feathers, and fur. One of a flea's characteristics long legs. Especially, back legs are longer. These long legs can be bent into several joints. When the flea jumps, it bends its legs and resilin, elastic protein pad, stores the energy. When the bent legs are held by a tendon, the flea releases the tendon and legs rapidly become straight.[5]


The flea uses its mouthpart to suck blood. The mouthpart is adapted to pierce the skin of human and animals, since the flea is a external parasite.[6] The mouth of the flea is attached to its head. The mouth parts form a drinking tube that looks like a needle. When the flea cuts the skin of animals of human, it uses laciniae which is attached to the flea's mouthpart. The epipharynx acts like a needle on the flea's mouth. The laciniae surround the epipharynx. The laciniae and the epipharynx form the stylet. The flea has only one stylet. The flea sucks the blood through its stylet.[7] The prementum and labial palps make the labium which supports the stylet.[8]


The flea seems to have a smooth skin, actually, the flea's body is covered with sclerite which is a hard plate. The sclerite protects the flea from everything that is try to harm the flea. The flea's sclerite, the exoskeleton, does not seem like it is covered with anything. However, the sclerite is covered with tiny hairs.[9]


Flea larva.

The flea life cycle involves complete metamorphosis with the characteristic four stages; egg, larva, pupa, and adult. Usually 50 percent of population of flea are in the egg stage, 35 percent are larva, 10 percent pupae, and 5 percent is are adults. The flea's life cycle starts when the female flea lays eggs. The adult fleas must be fed before they begins the reproduction. The female fleas lay the eggs up to 20 per day. Usually female fleas lay about 600 eggs in a life time.[10]

Flea Egg

When the female adult flea lands on on animal's fur or skin, it lays the eggs, and these are spread to other animals, such as dogs and cats. Also when the animals that have flea eggs on their fur and skin, jump and eggs are spread to many places too. It is because even though fleas are parasites, they do not have any substances that make fleas sticks or adhere on something.[11] It takes about two days to two weeks to hatch from the eggs. When the flea hatches from the egg, that little baby flea is called larva.[12]

Flea Larvae

A just hatched larva is usually about 1/4 inch long. Larva is blind when it hatches from the egg. It usually tries to avoid the lights. This means even though fleas cannot use their eyes, they respond to lights.[13] It normally takes a week to few months to develop. It does not directly suck blood from animals.[14] Actually, larvae do not have legs, but they do have bristles on each segment of their body. There are thirteen segments on the larvae's body. Three of them are thoracic and ten of them are abdominal sections. Flea larvae are known to fake death. They pretend that they are dead when they feel the movements or vibrations. Also when the animals try to scratch their skin, the larvae wrap itself around the animals' fur. When the larvae are ready to become pupae, they begin to build pupal casing. Pupal casing will help flea to develop. The larvae do not really move from the area where they hatched.[15]

Flea Pupae

At the third and final stage of the larvae, development of pupae begins. Larvae spin the pupal case with the collection of materials that larvae collected from surrounding area. When the larvae spin the materials, these become silk materials. Larvae put a water-tight cocoon to make the silk material invisible, so they can camouflage. When pupae are inside of the case, they get eyes and legs. They develop into complete insects that suck blood. Pupae stay inside of the case only of a week or ten days.[16]

Flea Adult

When pupae come out from the case, they become adult fleas. When human find fleas on their animals, they are usually adult flea. Total population of adult fleas take minor place. Adult fleas usually live for two months to seven months. Male adult fleas emerge first from the case where they used to live. Even though male emerge first, female adult fleas outnumber male fleas. Just hatched fleas jump higher because they need to find food. After the female adult fleas eat, they start to lay eggs. Also female fleas have to prepare some food for fleas that will emerge soon. If the female flea wants normal amount of eggs, she can have several matings. However, if she wants a lot of eggs, she will need to have numerous matings. Fleas like to spend their entire life to be on their host.[17]


Flea lives on animal's fur

Most likely, fleas live on the animal's fur. When the hosts such as animals move or jump, fleas can fall. When they fall, they can move on to other animals. This is how they move to different animals and spread their eggs.[18] Sometimes, fleas can be found on the bird's nests.[19]Conditions surrounding the area where fleas live is most important thing. Fleas must live in the warm temperature. Actually, fleas can live in the cool temperature. However, they cannot live long. Temperature around the area where fleas live should be between 80 degrees and 90 degrees. Also humidity is as important as temperature.[20] Throughout the winter, people can find fleas on the animals a lot. It is because fleas look for warm place throughout the winter and they cannot live in the cool places.[21]

Fleas must suck warm blood to live. This is one of the characteristics of parasites. It is because fleas do everything when they are fed. However, for larvae, they usually eat everything that is available to them, such as dead insects and vegetables. For adult fleas, they must have blood to mate and survive. When female adult fleas are fed, they will begin to lay eggs. Depends on how much food they eat, fleas will live shorter or longer.[22]

Problems and Treatments

Flea bites on the back of a human

Since fleas are parasites, they usually live on animal and they suck blood from them. However, this activity can be very harmful for host animals. Most problem of fleas is they make animals have diseases. Also when the fleas land of humans, they can make humans to have a fever and itch. This becomes huge problems to pet owners. Here are the diseases that flea can spread to the hosts when they suck blood from them.

  • Flea bite dermatitis: when fleas suck blood from the animals, they put a small amount of salivary gland secretion into the body of animals.
  • Plague: Rodent fleas usually transmit the infections between rats or rats to humans.[23]
  • Murine flea-borne typhus: this is caused when Rickettsia is passed to humans by fleas.[24]
  • Tapeworms: fleas can transmit tapeworms to animals by serving as an intermediate host.[25]

Fortunately, there are many solutions to get rid of fleas. People can use some products of fleas to get rid of them. People can put some chemicals on their pets. If they do not want to put chemicals on the animals' body, they can use some nature things to get rid of them. Also people can vacuum the carpet, so fleas are not spreading to everywhere.[26]


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