Siphonaptera the FLEA 

   Know the Flea, Know your Enemy  

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Last-Modified: 05/17/06 10:27  - 

Did You Know?

As a flea jumps, its rate of acceleration is 20 times that of a space shuttle during launching. It reaches a speed of 100 m per sec within the first 500th of a second

Did You Know?

The wormlike larvae of fleas are eyeless and legless. They do not suck blood, but feed on digested blood excreted by the adult flea, and flakes of human skin.

Fleas are very small robust insects that are also parasites. Defined by any dictionary as 'self-seeking hangers-on'. They live, as all parasites do, human or otherwise,  by living on something or someone else, sucking nutriment directly from their victim. In the flea's case, this means drinking the 'host' animal's blood.

Siphonaptera, is the Latin name for the collective species of fleas and there are around 3,000 different species currently recognized by flea-authorities around the world. 95% of these occur on mammals with around 5% occurring on birds. 

Whatever an adult flea is living on, is commonly referred to as the 'host' and different species of flea are usually named after the 'host' on which they were first discovered or are most usually found. Such as the cat flea, dog flea, hedgehog or rabbit flea for example. Some fleas have developed particular liking for particular hosts, though most fleas will 'holiday' on anything alive given the chance. In fact it has been said that fleas even have fleas and those fleas have fleas, or some equally obnoxious parasite, ad infinitum.

Infestation by fleas may cause severe inflammation of the skin and intense itching. Although many animals acquire partial immunity after constant or repeated attacks, occasionally individuals can become sensitized after exposure and develop allergies.

Species that attack man and livestock include the cat flea  - Ctenocephalides Felis, the so-called human flea - Pulex Irritans, the dog flea - Ctenocephalides Canis, the sticktight flea  - Echidnophaga gallinacea, and the jigger, or chigoe flea - Tunga penetrans.

Poultry may be parasitized by the European chicken flea - Ceratophyllus gallinae, and in the USA by the western chicken flea - Ceratophyllus niger.

Fleas are not always peculiar only to their namesakes. For example, the most common flea on both dogs and cats is the cat flea, Ctenocephalides felis, but both cats and dogs can also occasionally be affected by other fleas, such as rabbit and bird fleas.

Ctenocephalides canis - the dog flea, which has been previously found in great numbers on dogs, but rarely on cats, is becoming more scarce as dogs are more frequently kept in environments similar to that of the domestic cat. Whilst the domestic cat remains a free spirit and able to roam wherever, it will get fleas. The domestic dog is no longer such a pack roamer and usually is well cared for so the best habitat for the dog-flea is in decline. However, as has been said, any flea will take on the maxim: ' any port in a storm ' and will drink  / feed off any animal it can land on, it still only prefers its general host though. The human-flea, in some countries is almost relatively extinct due to greater cleanliness and awareness of such critters.

Adult fleas are about 1/16 to 1/8-inch long, dark reddish-brown, wingless, hard-bodied and cannot be crushed between fingers, they must be nipped between the finger nails until you hear a snap. They have three pairs of legs and the back legs are very enlarged and enable jumping. The legs can be recoiled like springs and then released with an explosion of  energy. Fleas are excellent jumpers, leaping vertically up to seven inches, moving up to thirteen inches across surfaces. A flea can jump a 250 feet high and 450 feet along in human terms, as long as the starting point is of sufficient resistance. This is, pound for pound, the greatest jump of any creature on the planet.

They are flattened very thin vertically, this allows easy movement between the hair, fur or feathers of the host. Even though they are adapted for this, for obvious reasons maybe, there is no sheep-flea; a sheep's coat is too thick to allow convenient movement. 

The adult flea have piercing-sucking mouthparts and spines on the body projecting backward. Also, there is a row of spines on the face known as the genal comb. They feed by piercing the skin layers of any warm animal and just like the aphid that pierces the skin of the plant, they do not do much sucking, but rely on natural pressure of the body. In our case, our natural blood-pressure forces blood out straight into the mouth of the flea.

Generally, this blood would coagulate or thicken to try and block the wound, but the flea, just like most other blood-sucking insects,  introduces a chemical that stops this coagulation. 

Did You Know?

Most birds have fleas; there are 17 species of flea found only on Swallows and Martins.

After mating, and a good feed, the female has sufficient protein to develop eggs in her body. The eggs are smooth, oval and white. But they are also sticky; this natural glue attracts local debris, that acts as camouflage.  

Larvae are 1/4-inch long, slender, straw-colored, brown headed, wormlike, bristly-haired creatures, with 13 body segments, that are legless and have chewing mouthparts. They are continually active and avoid light by burrowing into the nest or carpet pile. 

Pupae are enclosed in silken cocoons covered with particles of debris. The larvae feed mainly on human skin flakes and even the discarded faeces of the adult flea. The adult sucks copious amounts of blood and this is readily digested and disposed of, because this digestion is inefficient, perhaps 70% of the adult's waste still contains nutrition.

The fleas have 4 phases of development - the egg, the free-living larva, the pupa and the imago.   Imago:  The adult sexually mature stage in the life cycle of an insect after metamorphosis.

The Flea life cycle

Understanding how fleas live, and breed, makes it easier to understand the best methods available to eradicate a flea problem.

EGGS.   One female adult flea can lay anything from one to FORTY eggs each day, with the highest concentration of egg-laying occurring in the final two to three days of life. Eggs are oval, around 0.5mm long, white and rounded at both ends. The eggs are not sticky so once laid, they immediately fall onto the ground, wherever the host is at that time. They are produced about one each hour.

Depending upon the temperature and most importantly, humidity, the eggs will hatch into larvae within two to ten days. Humidity below 50% may cause them to dry out and become food for luckier hatchlings. The environment in which the eggs are deposited is therefore of prime consideration to flea survival rate and helps to explain why warmer winters and hot summers have increased flea populations considerably in recent years. Homes should be well aired and this will help the drying effect and possibly protect against not only fleas but also the dust-mite.

LARVAE. A larva will hatch from an egg using a chitin tooth - an egg splitting spine on its head. This disappears when the larva changes into the second of its three 'moults' or development stages. It is this tooth that is changed by modern oral flea treatments. Treatments contain an insect development inhibitor renders the chitin tooth ineffective, this prevents the larvae from cutting his way out.

Larvae are semi-transparent and sparsely covered in short hairs. They are usually white with a yellow-brownish head and are generally quite active. They are dependent on a diet of adult flea faeces for survival, but will also feed on other organic debris in your carpet. In this domestic environment, flea larvae are found at the base of the carpet pile, where they can encounter food, are sheltered by the canopy of carpet fiber and can keep away from direct light. So it is clear that the more powerful any vacuum cleaner you have the greater ability for it to suck these little varmints out and into the dust container for disposal.

PUPAE.   After the third moult, the larva moves to an undisturbed place to begin spinning a silk cocoon coated with particles of debris picked up from its surroundings for use as camouflage.   It is within the cocoon that the larvae turns into the next stage of development - the pupa. Pupae subjected to suitable hatching conditions can emerge as adult fleas as early as three to five days following pupation. From this stage, the adult flea develops. The fully formed adult flea remains in the cocoon until stimulated to hatch by, for example, warmth, vibration and even exhaled carbon dioxide from a passing potential host - which includes the human! 

Under certain laboratory conditions fleas have lived dormant like this for up to five years. So even an empty house can harbor these problems until the unsuspecting new tenant moves in creating the phenomenon known as the 'pupal window' and you need to be aware of it before effective flea treatment can begin.

Environmental sprays and powders cannot readily penetrate the cocoon and therefore have no effect on the maturing adult inside if used on their own. These fleas continue to hatch from their protective cocoons and, unless the flea control regime is maintained, will be the source of the next generation of fleas ready to cause you and your dog more problems!

ADULTS  Almost immediately after the adult flea has hatched from its cocoon, it will begin looking for its first blood meal. Unlike the flea larva, which tends to move away from light, adult fleas move upwards and towards the light, in order to be in a better position to locate a suitable victim.

The flea's eyesight is not brilliant and so warmth and carbon dioxide in the air appear to be answerable for helping it find its goal. Air currents will be changed by a cat or dog moving past the adult flea, the carbon dioxide increases and the flea detects these changes and jumps in the hope of landing in close proximity to the waiting adult. Adult fleas have been known to jump as many as 10,000 times in succession, whilst trying to leap onto a passing cat or dog - the flea knows they are close by but it's more a question of luck than judgment when trying to make a successful connection between the hooks on the flea's legs and the fur on the cat or dog.

However, once satisfactorily 'anchored', the flea will immediately begin to feed and the females will begin laying eggs after only 48 hours after the first feed. Before drinking the blood, the flea secretes special enzymes within its saliva into the wound. This substance softens and spreads the skin tissue, assisting with feeding. More helpfully the saliva contains an anti-coagulant making the blood flow. This saliva is usually the cause of allergic reactions in cats, dogs - and humans.

Once on a suitable host, the adult fleas will remain there until they die, which is usually within one or two weeks. Unfortunately for the pet, although providentially for the parasite population, females tend to live longer than males and there are naturally more females than males. If the animal is left to groom itself normally and cats groom more thoroughly than dogs on the whole, many adult fleas will be dislodged or swallowed naturally. However, if for any reason, the animal is unable to groom itself - it may be ill for example, then the owner should groom it more frequently than usual, to complement their pet's natural methods of flea control.

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Frontline® Plus contains two active ingredients: fipronil and (S)-methoprene. By specifically targeting the flea neuron, fipronil kills adult fleas, flea eggs and flea larvae. It’s also effectively kills all stages of ticks. (S)-methoprene is a insect growth regulator. It prevents flea eggs, larvae and pupae from developing into adult fleas.

Bacteria  - Microscopic single-celled organisms found wherever life is possible. Generally 0.0001–0.005 mm long, they may be spherical (coccus), rodlike (bacillus), or spiral-shaped (spirillum) and often occur in chains or clusters of cells. True bacteria have a rigid cell wall, which may be surrounded by a slimy capsule, and they often have long whip-like flagella for locomotion and short hair-like pili used in a form of sexual reproduction. A few bacteria can use simple chemical substances, including carbon dioxide from the atmosphere, to manufacture their own nutrients, but most require a source of carbon derived from living organisms (i.e. organic carbon) plus other nutrients for growth. Some bacteria can reproduce every 15 minutes, leading to rapid population growth.

The most important role of bacteria is in decomposing dead plant and animal tissues and releasing their constituents to the soil (see carbon cycle). Nitrogen-fixing bacteria in the soil or sea convert atmospheric nitrogen gas to nitrites and nitrates, which can then be used by plants (see nitrogen cycle). Cheese making and fermentation reactions depend on bacteria. Bacteria also play an important part in animal digestion, especially in ruminants. However, certain (pathogenic) species may cause disease while others, such as Salmonella, can cause food poisoning.

How Does Your Body Fight Infection?

Immunity   -  The resistance of the body to infection, especially resistance due to antibodies. Babies have passive immunity from antibodies transferred from the mother’s blood through the placenta. Active immunity involves the formation of antibodies after exposure to an antigen - bacteria that invade the body during an infection are antigens. The two different kinds of immune response produced by antibodies involve: white blood cells called T-lymphocytes - produced by the thymus, which produce cells with antibody properties bound to their surface and are responsible for such reactions as graft rejection; B-lymphocytes, which produce cells that release free antibody into the blood.

Leucocyte - lymphocytes - or white blood cell. A colorless cell found in large numbers in the blood. There are several kinds, all involved in the body’s defense mechanisms. Granulocytes and monocytes destroy and feed on bacteria and other microorganisms that cause infection -  see also phagocyte. The lymphocytes are involved with the production of antibodies.

Phagocyte   -  A cell that engulfs and then digests particles from its surroundings: this process is called phagocytosis. In vertebrate animals, phagocytes are a type of white blood cell that protect the body by engulfing bacteria and other foreign particles.

Immunization is the production of immunity by an injection containing antibodies against specific diseases e.g. tetanus and diphtheria, which provides temporary passive immunity, or by vaccination, which produces the longer lasting active immunity.

Antibody   -  A protein produced by certain white blood cells  - lymphocytes that reacts with a particular foreign particle e.g. a bacterium,  that has entered the body. The antibody helps to destroy the foreign particle, known as the antigen. If the same bacteria invade the body in future, many more of the same antibodies are produced, enabling the body to destroy the bacteria very rapidly and so resist infection. This provides the basis of  immunity. Antibodies are also responsible for the rejection of foreign tissue or organ transplants. See also monoclonal antibody.

Monoclonal antibody  -  A type of pure antibody that can be produced artificially in large quantities and used, for example, to distinguish the major blood groups. Mouse lymphocytes producing the required antibody are fused with mouse cancer cells; the resulting hybrid cells multiply rapidly and all produce the same type of antibody as their parent lymphocytes.

Whilst all this bodily protection sounds wonderful, the problem with MRSA, is that there is no defense to it, no answer to its attack.

Did You Know?

In 1666, to help counter the spread of plague, the British Parliament decreed that all bodies had to be wrapped in a woollen shroud for burial. This decree provided wool-makers with a constant source of business for nearly 150 years.

Fleas have been around for millions of years - a fossilized flea found in Australia is said to be 200 million years old. It does not differ significantly from today's fleas. Different species can be found from the Arctic Circle to the Arabian deserts - even penguins have fleas which counteract the cold by ensuring that their growth into adulthood coincides with the time when penguins are sitting firmly on their eggs, thereby keeping both fleas and their young in a warm environment!

Adult cat fleas are generally around 2mm long, with females being larger than males. The largest species of flea is Hystrichopsylla schefferi - a flea found in the nest of a mountain beaver in Puyallup, Washington, USA in 1913. The female can grow up to 8mm long. This is almost a third of an inch.

During their life cycle, cat and dog fleas undergo complete metamorphosis, going through the four developmental stages from egg to larvae, pupae and on to adulthood. As adults, once they have found a suitable host - your dog or cat for example - they can remain there until they die, or are groomed off - their life on your pet is only about 1-2 weeks. It is generally a misconception that they jump freely to other hosts, however, a jumping flea may land on a passing mammal and make it a home. This host could be you as it is attracted to heat and vibrations and leaps out where it thinks it will find food.

As well as this fleas do readily just drop off, if looking to reproduce, but they can also find a mate within the fur of the host, so there is no hard and fast rule.

Like most living creatures, fleas, in all stages of development, are affected greatly by humidity and temperature. They need water in their environment just as we do, and will die without a suitable environment; liking quite a warm humid temperature, where they will thrive as long as they have mammals as a symbiosis companion.

The most important thing to learn about the flea is that it is not the adults that present the main problem in flea control. Research has shown that, in an average household, adult fleas only represent around 5% of a total Siphonaptera population. Flea pupae account for around 10%; fleas in the larval stages around 35%; whilst flea eggs make up a whopping 50% of the total! Adult fleas will die naturally within one or two weeks following their arrival on your dog or cat. Simply treating your dog or cat with an appropriate insecticide to kill the adult fleas means that 95% of the flea population are unaffected and are simply left to develop into new adults all around your home.

Because of this time-bomb situation you must accept that you have a potential catastrophic set of circumstances to contend with. In some situations where fleas have been left to flourish, say when dogs or cats have been abandoned and locked up in an enclosed environment. SPCA inspectors have been met on occasion with a ravishing army of literally hundreds of thousand of fleas. One female inspector has said that as she was wearing a skirt was 'attacked' and she could hardly see any of her lower legs due to the massing of fleas attaching themselves on to her in some feeding frenzy.

Things in most homes would never get this bad but could come quite close. If you keep animals you must also accept that you will get fleas. The flea-population is directly proportional to how you cope. Without a doubt your best defense is the humble vacuum-cleaner, and the more powerful the better. Some cleaners are so powerful that they will lift the carpet slightly off the floor and suck out quite a lot of debris such as the aforementioned human skin.

[  It was this site some years back that first mentioned the vacuum cleaner as the best tool to defeat fleas; now they all refer to it. ]

See DUST MITES.   

See   ANTS

See BEDBUGS

See  HEAD LICE

See Mosquitoes

A good Hoover will takes away eggs, larvae, some fleas and of course their potential food source. So if you think that you may have an infestation you must Hoover daily if not twice daily. This breaks the life-cycle.

The larvae will feed on human skin flakes, scabs from flea bites, any organic material really and flea droppings. The adult flea will gorge on the blood of its host and as its digestion system is not that efficient its excrement or faeces will contain a lot of undigested clotted blood. The droppings are generally moon shaped and the color of coffee beans and a staple diet for the flea larvae.

Dogs and cats, especially those in rural areas, occasionally pick up fleas other than Ctenocephalides felis or Ctenocephalides canis, such as those listed, through burrowing into the living quarters and living environments of the different host species, where newly hatched fleas may be waiting. Bird fleas can even be collected by pets because they are very common in nesting boxes and often migrate out of them. Many drop to the ground, from where any passing mammal can be 'preyed'.