The lifecycle of a flea

Most people are only too aware of the existence of the humble flea, and even more aware of the trouble that it can cause them and their pets. However, despite the modern-day advances in treatments available, we still find that many people have great difficulty in controlling fleas, and the associated diseases which can come with flea infestation.

The four stages

The flea is an insect; thus, the lifecycle is typical of a number of insects (for example, butterflies) having four stages of development.

The eggs are laid by the adult flea, one egg at a time, while it is ´riding´ on your pet. The eggs which are produced fall off the animal and drop into the surroundings. This could be outside the supermarket, or in the park, but the vast majority will be in the place where your pet spends most of its time. This could be in its bed, on your sofa, on your bed, or any other place where your pet spends a significant part of its life.

These eggs are tiny, but visible to the naked eye if you know what to look for.

In normal surroundings, eggs hatch in a couple of days, particularly in a heated house. If it's particularly cold, it can take up to a couple of weeks.

The flea grub or larva hatches by hacking a hole in the eggshell with a specially developed area of the mouth, usually referred to as a ´milk tooth´. This is important as we will see later when we discuss control.

The larva is sticky and covered in hairs, so it's quickly camouflaged as it's coated in any dust or debris in its surroundings. It feeds on food particles present in the dust and debris.

Flea larvae rapidly move away from light, so congregate anywhere where it is warm, dark and dusty. For example, between armchair cushions.

The larva will live and feed here for 2-3 weeks on average, but up to 3 months if necessary. It will grow to be about 6mm long, but hardly visible because of its camouflage.

Once the larva has grown sufficiently, it will spin itself a silk cocoon, just like a caterpillar.

Having covered itself in sticky silk, it is again disguised by the dust and debris in its surroundings. In here it will metamorphose into the adult flea. It can stay alive for up to 2 years before hatching, which can be triggered by vibrations.

Adult fleas are about 2-4mm long depending on the species. They are flattened from side to side to allow them to run through their host's hair.

They can live for several weeks feeding on their host's blood. And, once they have fed, they are able to lay an egg. They can repeat this process up to once every half an hour when at their peak, and can lay more than 300 eggs in a lifetime.

Adult fleas are attracted to anything that is the same temperature as blood – whether it's a human, dog or cat. Although fleas have species which they prefer to feed from, it is a case of any port in a storm. Many fleas seen on dogs are technically cat fleas, and most fleas biting humans are coming from their dog or cat.

Jumping helps them leave and access new hosts. Despite popular belief though, most fleas do not pass animal to animal but stay with the host that they first attacked. Most infections are picked up directly from the environment. Although other infected animals will be contributing to the pool of new infestation by shedding eggs, most animals in fact set up their own private supply of pet fleas.

When a flea bites, it first blows saliva under their host's skin to stop the blood clotting while it feeds. It is the body's response to this saliva which causes the reaction which we understand as a flea bite.

With the occasional flea bite, just as we would immediately pay attention to the area and attempt to remove the source of the irritation, so do our pets. Their defence is usually to swallow the flea, hence removing it from the site.

If the attack is repeated, problems of a much more severe nature develop. These include:

Flea allergic dermatitis
Tapeworm infestation
Bacterial skin disease and seborrhoea
Anaemia from blood loss, particularly in heavily infested small puppies and kittens.

Often a successful eradication of fleas required a combination of products, particularly in the early treatment stages of an outbreak. Treatment is aimed at two main areas:

Treating the adult fleas on the pet
Treating the environment

Considerable combing only removes around 10% of the burden on a pet, so shouldn't be relied on.

Bathing is a good first step to remove the fleas and debris in an animal's coat and to generally stimulate a healthier environment for the skin. However, once the coat is rinsed and dried, there is no lasting residue to resist reinfection which can begin within an hour of returning to the infected environment.

Collars can play a useful role in flea control, and most are active for about 3-4 months. Ensure you read the instructions carefully before buying or using a parasite prevention collar. However, collars can cause local skin reactions and sensitivities.

Note: Cat collars MUST have an easily breakable fastening or a safety elasticated strap.

The lifecycle of a flea

The four stages

Eggs

Larvae

Pupae

Adult

The problem

Treatment

Combing and bathing

Collars

Sprays

Spot-on

Treating the environment

Conclusion

Flea facts