Revealed: The Cat Fleas Life-Cycle

The life cycle of a cat flea ( Ctenocephalides felis ) begins when adults (both male and female bite) find a warm-blooded host. A host is a living animal on which a parasite like a cat flea feeds.

Fleas are described as ectoparasites, meaning they feed on the hosts’ blood externally.

Fleas feed on humans where genetically appropriate hosts (a cat) are absent, but this significantly impacts the fleas fertility.

Consequently, if the cat flea feeds on anything but a cat, it will find it difficult to develop viable eggs.

Once fleas latch onto a host, they move vertically to acquire a suitable feeding site to extract a blood  meal.

A female cat flea has been successfully mated and appropriately fed at this stage in the life cycle. She begins laying eggs at a rate of twenty or so per day.

Cat fleas usually lay eggs on the host animal, but eggs quickly fall off because they have no viscosity. As the cat moves around, eggs drop onto floor coverings, bedding and sofas, etc.

The cat flea will lay many hundreds of eggs during her lifetime, which could be as long as a year!

The average figures suggest that most fleas will be fortunate to live a few weeks. But as with all things in the natural world – there is always an exception to the rule.

Cat fleas eggs are very small and difficult to see without the aid of a magnifier.

Typically the cat fleas eggs are; 0.2mm in length, oval in shape; light cream in colour; and hatch within a few days. This will Depend on how conducive prevailing environmental conditions are at the time of laying.

At this stage of the fleas life-cycle, larvae will have distinctive features. Cat flea larvae have a brown head with a couple of small antennae, followed by thirteen body segments and two projections from the rear end called anal struts.

The body is light brown in colour, and the segments have hairs projecting from them.

Larvae are big enough to be seen relatively easily by the naked eye because they grow to 5mm long.

The important thing to remember about the larvae is that they tend to develop in dark, undisturbed places. These low foot-fall areas keep the larvae safe from trampling feet, bright light and your vacuum.

These places must be the first to be intensively vacuumed before considering any flea treatment.

It’s widely reported that flea larvae must consume a quantity of what is termed flea dirt (dried blood that has been digested by the adult cat flea and deposited on surfaces as faeces).

As the larvae mature, they pass through two or three moults or instars.

This portion of the cat fleas life cycle lasts for a few weeks. However, this can be prolonged. If environmental conditions are not conducive, the process could take eight months!

The larval stage of the life cycle is where the fleas are at their most vulnerable. Small fluctuations in humidity and temperature could negatively impact the survival of the larvae.

Unfortunately, the adults have few such concerns.

Once mature, flea larvae quickly construct a silken cocoon in which they pupate and develop into an adult cat flea.

The time that it takes to develop into an adult flea is dependent on the quality of the environmental conditions. In most cases, it will take from a week to 14 days.

This is not the end of the story, though – read on.

Adult fleas might be ready to feed, but they won’t hatch unless they receive the right stimulus.

Adult fleas can sense all that is going on around them. This is in part due to a highly specialised sensory organ in the fleas posterior called the sensilium.

The adult fleas will emerge in response to vibration, carbon dioxide or fluctuations in humidity.

Very often, fleas can remain ready to emerge from their cocoons for as long as a year.

Properties where nothing has set foot in them for weeks or even months pose an unpleasant prospect. If infested cats have been present, it is horrible. Open windows/cat flaps allow feral and/or untreated cats to enter and deposit fleas and flea eggs.

When this happens, hundreds, or in sporadic cases, thousands of fleas emerge within moments of each other.

At this stage of the life cycle, the fleas will be hungry—they start crawling vertically up the inside of trousers, where they feed covertly before dropping off.