There are about 2600 species and sub-species worldwide, but the most common flea found on cats, dogs, rabbits, small rodents and livestock is the Cat flea - Ctenocephalides feli.


Three other fleas found in South Africa are:

  • Ctenocephalides Canis – Dog Flea, which is frequent on dogs, and almost never seen on cats.
  • Pulex Irritans and Pulex simulans – Human fleas and can inhibit other species.

They are small wingless insects. The adults suck blood from mammals and the immature are scavengers. The preferred host is the cat, although they can be found on other mammals such as dogs. Fleas do not live on humans, though they can bite people in attempt to get a blood meal.

 The Life Cycle of the flea:

 There are four stages to the life cycle of the flea, which, depending on the environmental temperature and humidity levels, can take anywhere from 3 weeks to months to complete.  

The four stages are: egg, larva, pupa, and adult (Imago).

The Eggs:

 The adult female flea has to have a blood meal in order to produce eggs; she can lay up to 60 eggs per day. Once the eggs are dry, they will fall from the coat of the animal, and into the environment. The eggs are dry, creamy coloured and 0.5mm long, hatching after an incubation period of up to 21 days after being laid, depending on the environmental conditions.  Eggs will not hatch on the host.

 The eggs make up 50% of the flea population in the environment.

The Larvae:

 The emerging larvae have no eyes are extremely sensitive to light, as well as low humidity. They have 13 segments and do not have legs. They move around by using setal rings and abdominal hooks that are located on the body segments.  The head capsule is well developed with chewing mouthparts. Mature larvae are about twice as long as adult fleas (3-5.2mm).

Initially they have a white colouration, but later turn into reddish colour from ingesting adult flea frass (faeces), which contains 90% of the protein from the original blood meal, from the environment, Larvae will also scavenge on other organic debris such as dander and tape worm eggs.

Due to their light aversion and sensitivity to low humidity, they will burrow down deep into the carpet base, grass or sand, if they are in a sandy or grassy area, they will prefer shaded areas.

 The larvae will go through 3 moults, before spinning a cocoon for pupation. Depending on temperature, humidity and food availability, the larval development can range from one week to several months.

 The larvae make up 35 % of the flea population in the environment.


Cocoons are comprised of silk and collected debris from the environment for camouflage. It has a sticky outer coating that allows it to hide deep in the carpeting and not be easily removed by vacuuming. Under favourable conditions the cocoon stage can be 4 to 14 days. If the conditions are unfavourable, they can remain within the cocoon for several months.  

 Once the conditions are favourable and the pupa gets a sign that a host is near, they will come out of their cocoon to feed.  The triggers for hatching and alerting them that a host is near are vibrations, excessive heat and carbon dioxide.

 The pupae make up 10 % of the flea population in the environment, and while they are encased in their cocoons, nothing can kill them.

 The Adult Flea:

Adult fleas are wingless and flattened. Their colours can range from polished reddish brown to black, they are usually 1.5 mm to 4 mm long, they have large hind legs designed for jumping up to 100 - 200 times their own body length and have mouthparts for piercing and sucking. Antennae are short and inserted into grooves behind inconspicuous eyes.

 Once the adult emerges from the cocoon, they start seeking a blood meal immediately, if they do not receive a blood meal within 48 hours, they usually die from starvation. Due to grooming habits of the host, the life expectancy is not usually long and can often only be 2 to 3 weeks.

 Direct transfer from host to host by fleas is low. Female fleas tend to remain with their host, but males are more likely to cross directly between animals. The greatest number of flea transfers takes place in resting areas where the animals sleep in very close proximity.

 The adult fleas make up 5 % of the flea population in the environment. And for every 1 male flea there are two female fleas. The adult female flea has to have a blood meal in order to produce eggs; she can lay up to 60 eggs per day, and can lay eggs for over 100 days.


Did you know?


If an animal has 30 fleas, 20 of which are female, after 7 days – they would have laid approximately 7 000 eggs!


In 3 weeks, one flea can pass through its entire life cycle and can lay 1000 eggs. In another 3 weeks, those eggs can hatch and lay 1,000 eggs each, so within 6 weeks, it is possible to have a million new fleas.


Fleas drink blood using two mouth parts. One part squirts saliva and partially digested blood into the host, and the other sucks blood from the host. About 60% of fleas will feed within 5 minutes of jumping onto the host, and almost 100% of fleas are engorged with blood within 1 hour of being on the host. The female consumes 15 % of her body weight in blood, which passes through her digestive system and is defecated out onto the skin.

 Health Threats

 Although fleas are so small, they can cause great damage to animals, especially if the animal is very young, old, immune compromised or if there is an excessive parasite burden.


Anaemia is caused from having an inadequate amount of red blood cells and if the case is severe enough, it is a life-threatening condition. Small animals with large infestations of fleas can lose enough bodily fluid to fleas feeding that dehydration may occur.

 Most owners do not even realise that their animal can be in a life threatening situation from excessive flea burdens, causing Flea Anaemia. The first step is recognising the problem. The affected animal will have pale gums (normal gums are shell-pink; anaemic gums can be completely white). In the advanced state, the patient will be listless and even cold.  Cats will sometimes eat small pebbles or cat litter when they are anaemic.

Immediate veterinary treatment should be sought by any animal suspected of having Flea Anaemia.

Flea Allergy Dermatitis:

 Flea Allergy Dermatitis or FAD is the most common skin disease in both dogs and cats.  The affected animal develops an allergic reaction to chemicals and proteins in flea saliva.

 When a flea bites, the antigen in the saliva causes the animal’s immune system to ‘overreact’ causing  an inflammatory response which leads to severe itching, in turn leading to self-trauma (biting and scratching) as well as secondary bacterial infections.  The intensity of reaction doesn’t correspond to the number of fleas present, and even one flea can be enough to set off this cascade in a sensitive pet.

 Symptoms FAD include: redness (erythema), bumps (papules), pustules (pus-filled bumps), and scabs (crusts) also, in severe cases, hair loss will occur in affected area.

 Cats with flea allergy dermatitis may develop a variety of skin problems, including feline eosinophilic granuloma (This is a rash comprising raised red to salmon-coloured and flat-topped, moist bumps scattered on the skin surface) , miliary dermatitis (distribution of skin lesions, with no identifiable pattern) or self-inflicted alopecia (excessive licking and grooming resulting in hair loss).

 Severe FAD is most commonly identified in cats by hair loss or military dermatitis in the neck area, spreading to the shoulders and lower back.

IMPORTANT NOTE: When treating for fleas on an animal with FAD is extremely important to use a product that will not cause the flea to bite before dying, it is best to use a product that kills the fleas on contact.


 Fleas are the intermediate host for Tapeworm or Dipylidium caninum.  The tapeworm is unable to complete its life cycle without the presence of fleas in the environment.

 Regardless of whether the owner may have seen fleas, the animal must have ingested a flea in order to have tapeworms. Consequently, tapeworms are more common in environments that are heavily infested with fleas.


IMPORTANT NOTE: It is therefore important to treat an animal that has fleas, for tapeworm.

Common Myths:


·          “I never see fleas on my pet, so they can’t be causing this problem.”   Just because fleas are not seen, that does not mean that they are not there. An itchy pet often grooms so much that adult fleas are removed, making them hard to find.


·          “My pet is still itchy in the winter, so fleas can’t be part of the problem.”  In our warm Durban climate, as well as in the homes, fleas will still survive in low numbers year-round.


·          “My pet can’t have fleas because he/she lives entirely indoors.”  Fleas love homes, because the temperatures are more regulated. Even if the pet came home with three fleas at one point, this could cause an infestation


Checking for fleas – even if there are no visible adults:

 Black specks on the animal may very well be faeces or "flea dirt".  Many people assume that these black specs are flea eggs, they are not eggs.

To check if there is flea dirt on the animal can be checked in two ways:

Run a flea comb over the animal, making sure the comb reaches the skin through the coat, focusing on the neck and lower back. If black specks are on the comb once it is run through the coat, it may be flea dirt.


Place a white paper towel beneath the animal and rub your hands across its fur, focussing on the lower back and neck. If black specks appear on the towel, it may be flea dirt.

To confirm if the black specs are flea dirt put a drop of water on the black spec, if it turns red, then that is a confirmation that it is flea dirt.  WHERE THERE ARE FLEA FAECES, THERE ARE FLEAS.


Written by Cherece du Plessis

©  Cherece du Plessis 2018



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