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Everyone knows or has heard something about the life of fleas. How much of it is true? There are a lot of myths out there about fleas and how to control them. We will try to give some clear facts about fleas:
  1. Lifecycle
  2. Interesting Flea Facts
  3. The problems of fleas
  4. Controlling Fleas
  5. Why is your flea control not effective?

Flea Lifecycle


Flea eggs are laid in the coat of your pet while the flea feeds. The eggs are ~0.5mm in diameter. They have a white smooth surface and are easier to see on a dark background. They are easily shed from the pets coat and are generally in the environment within in 8 hours of being laid.
These eggs will hatch ion 1 to 10 days depending on the humidity and temperature. The flea eggs will not survive in a dry environment (less then 50% humidity)


When a flea larva hatches from the egg it is approximately 2mm long, whitish in colour and have fine hairs coating them. They are able to move around (may move up to 1 meter) and will generally head towards darker areas and areas where there organic matter. Here they will feed on organic debris, other larvae and adult flea dirt. Over the next 5-11 days the flea moults and double in size. This once again depends on temperature and humidity. IN the outdoor environment the most likely place a larvae will survive is shaded moist area. Indoors the environment in carpets and bedding etc is most suitable. When the larvae finish developing they produce a cocoon to become a pupae.

A flea cocoon is approximately 5mm long. Within 5-8 days the flea is ready to hatch with the right stimuli. Vibrations, carbon dioxide levels and temperature play a role in emergence of fleas. The adult flea can stay in the cocoon ready to hatch for up to 6 months if the conditions aren't right. This allows fleas to hold off hatching until the next season.
The whole lifecycle (egg to adult) can be as short as 12 days given the right conditions


A newly emerged adult flea is attracted to light and to pets by their movement, temperature and exhaled carbon dioxide. When the flea jumps on to the pet (they can jump ~0.5 metres in one jump !) they begin feed within the first few minutes. The female flea will begin to lay eggs 48 hours of her commencing feeding. Generally around 30 eggs/day are laid but it can reach 40-50 eggs per day. Laying can go on for up to 3 months …. That's a lot of flea eggs ! ... ~3000 in a female flea's lifetime !

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Some interesting facts about the adult flea:

  • The female flea must have a meal of blood before she can lay eggs, so fleas cannot breed on the ground - it all happens on your pet's coat 
  • The adult female flea consumes 15 times it's bodyweight in blood each day and lays approximately it's body weight in eggs. 
  • Adult female fleas don't tend to jump from pet to pet, once they find a host they stay attached for the rest of their life - drinking blood and laying eggs !
  • The adult only makes up ~5% of the total flea population in an environment. The other 95% are eggs, larvae, pupae waiting to become adults!

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The problems of fleas

Besides the general irritation they cause the health problems fleas can cause are:
  • FAD  - Flea Allergy Dermatitis. If you've ever had a dog or cat with this you'll understand how awful this condition can be for your pet. Constant itching lead to chronic skin disease. The drugs to control the itching have side effects and even worsen the condition of the skin>
  • Tapeworm - The flea tapeworm (Diphylidium caninum) is carried by fleas and causes repeated tapeworm infection in your pet. Treating for tapeworm is important but the fleas will just keep re-infecting your pet if they are not controlled
  • Anaemia - This condition is generally seen in juvenile cats and dogs or those how are old or debilitated. A decent burden of fleas can consume an enormous amount of blood each day. This can quite quickly lead to anaemia. Adequate flea control from when the puppy/kitten leaves their mother is important.
Fleas and Skin Problems
Fleas are often at the root of many skin problems in dogs and cats. Even if you can't find then they're often there. Many times simply using an adequate form of flea control has seen skin problems improve without the fleas ever being seen. The reason being, often pets are so sensitive to the flea bite that they quickly nibble or scratch at the site the flea is biting and remove it. But, the damage is gone. The flea has deposited some saliva under the skin leading to inflammation and itching.

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Controlling Fleas

There are literally hundreds of products claiming to control fleas. most of them probably do kill fleas but that is only part of the battle in total flea control. As you see from their lifecycle, their ability to breed is incredible. Suspending this is important too.
We generally take a 2-pronged approach:
  1. Kill the adult fleas which cause irritation (FAD) using Flea Adulticides
  2. Stop fleas from breeding using an IGR (Insect Growth Regulator)
1.  Adulticides
These are the topical or oral applications designed to kill the adult flea. Examples include Frontline PLUS, Advantage, Revolution, Fido's Rinse, Proban Tablets, Capstar Tablets. They must be given as directed to work effectively. If they are not given at the correct frequency and dose the fleas will keep feeding and breeding as normal

2.  Insect Growth Regulators
These are compounds which inhibit the development of the flea at the larval or pupal stage. So, eggs can be laid but they never hatch. They will not kill the adult flea. The most used example of an IGR is Sentinel Spectrum. It contains lufenuron, which is ingested by the female flea when she feeds, rendering her eggs not viable. Frontline PLUS contains a compound, methoprene, which coats the eggs as they are laid and has a similar effect.

Some recommended regimes for flea control:

  • Comfortis a flavoured tablet given once each month will kill adult fleas.
  • Comfortis PLUS a flavoured tablet given once each month will kill adult fleas, heartworm & intestinal worms.
  • Nexgard a flavoured tablet given once each month will kill adult fleas and ticks - including paralysis ticks
  • Simparica a palatable chew given once each month will kill adult fleas and ticks - including paralysis ticks
  • Bravecto a flavoured tablet given once every three months will kill adult fleas and ticks - including paralysis ticks
  • Frontline PLUS once every 2-4 weeks (will also control ticks at fortnightly dosing)
  • Advantage once every 4 weeks (the active ingredient of Advantage also has some IGR effect)
  • Advantix once every 2-4 weeks (will also control ticks with fortnightly dosing)
  • Advocate once every 4 weeks. Will also control heartworm and intestinal worms
  • Revolution once every 4 weeks
  • Sentinel Spectrum given orally once each month (can use Capstar tablets as required to kill any adult fleas that may appear, a flea rinse could also be used for this purpose )

  See all the flea control products available at VetStop for dogs here
  and for cats here

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Why is your flea control not working ?

  • Dormant Pupae: As we learnt before, the pupae can stay in a dormant state for up to 6 months. Given the right conditions these can hatch at any time and jump on your pet. A great number can jump on your pet at once and, as the topical flea agents don't kill fleas immediately, your pet appears infested. It can take up to 24hrs for some topical flea control products to kill all fleas on your pet.

  • Infested Environments: Your flea control may be going fine then there is a visit to another environment. When you come home you notice your pet is covered in fleas. This is due to the lag time in flea kill as described above. As long as you have been applying the flea control agent as per directions, these new fleas should slowly die off over the next day

  • All pets not treated: For those using IGR type flea control (eg Sentinel Spectrum), it is important that all animals in the environment are treated with an IGR. If eggs are laid on the coat of a pet not on an IGR, these eggs will hatch and infect any pet in the environment. It is important that all pets in the environment have some form of flea control for it to be effective for any of them.

  • Compliance: The frequency of flea control is important. Too long and the fleas get a chance to breed in a fertile environment for them and the numbers will continue to increase. In many areas of Australia year round use is required as the warm environment in heated house is ideal for the flea cycle to continue all year long.

  • Washing, Swimming: Although many products claim to have a degree of water resistance, regular shampooing may reduce the duration of action of some products.

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