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Siphonaptera is the Latin name for the collective species of flea and there are around 3,000 different species currently recognised by Siphonapterists in Britain. 95% of these occur on mammals with around 5% occurring on birds.
Whatever an adult flea is living on is 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 - cat flea, dog flea, hedgehog or rabbit flea for example.
However, fleas are not always peculiar only to their namesakes. For example, the most common flea on both dogs and cats is Ctenocephalides felis - the cat flea, 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 was 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 our pet cats.
Fleas have been around for millions of years - a fossil flea found in Australia is claimed to be 200 million years old and it doesn't differ significantly from modern 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!
During their life cycle, cat and dog fleas undergo complete metamorphosis, going through 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 will remain there until they die, or are groomed off - their life on your pet is only about 1-2 weeks. It is a misconception that they jump freely to other hosts.
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 relative humidity and temperature. The higher the humidity and temperature, the more the fleas like it.
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 flea 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 adulticide to kill the adult fleas, therefore, means that 95% of the flea population are unaffected and are simply left to develop into new adults all around your home.
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 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 they can be picked up by our pets.
Depending upon the temperature and humidity, the eggs will hatch into larvae within one to ten days. Humidity below 50% will cause desiccation and destruction of eggs. The environment in which the eggs are deposited is therefore of prime importance to survival rates and helps to explain why warmer winters and hot summers have increased flea populations considerably in recent years.
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 (which consists mainly of dried blood) for survival, but will also feed on other organic debris in your carpet.
In a home environment, flea larvae are found at the base of the carpet pile, where they can encounter food, are sheltered by the canopy of carpet fibre and can keep away from direct light.
The larvae develop through three moults, or changes, before reaching the pupal stage. The time this takes varies from 7-18 days and is once again dependent on the environmental temperatures. Moisture is vital and relative humidity below 50% will cause desiccation and death.
After the third moult, the larva moves to a quiet, undisturbed place to begin spinning a silk cocoon coated with particles of debris picked up from its surroundings for use as camouflage.
Development of the flea within the cocoon is also affected by temperature and humidity. Low relative humidity is harmful to the cocooned adult whereas higher relative humidity and higher temperatures result not only in speedier hatching but in bigger fleas!
Pupae subjected to suitable hatching conditions can emerge as adult fleas as early as three to five days following pupation. However, be warned - they can also remain unhatched for up to a year and can cause a re-occurrence of a flea problem if you relax your guard. This phenomenon is known as the 'pupal window' and you need to be aware of it before effective flea treatment can begin.
The pupal window. The pupal window is defined as the period in which fleas are still seen to hatch once an effective flea control regime has been started. By 'effective', we mean a regime that includes an oral insect development inhibitor with or without a household spray.
Environmental sprays and powders can't 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 pet more problems!
The pupal window usually only remains 'open' for 1-2 months following the start of a flea control regime but, in some extreme cases, fleas, in their protective cocoons, have been known to live within a house without food for considerable periods of time. This means the pupal window period may extend for several more months after treatment is started.
This cunning feature of the flea is the reason why continuous flea control is needed - the easiest method is to use the new monthly flea treatments simply given to pets in their food.
A flea's eyesight is not brilliant and so air currents and carbon dioxide in the air appear to be responsible for helping the flea find a target. Air currents will be caused by a cat or dog moving past the adult flea, whilst the carbon dioxide increases are caused by the cat or dog breathing 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 with females starting to lay eggs within 48 hours of the first feed.
Before taking in blood, the flea secretes saliva into the wound. This contains a substance that softens and spreads the skin tissue, assisting with penetration. The saliva also contains an anticoagulant to help with the feeding. It is flea saliva that 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 to two weeks. Unfortunately for the pet (although fortunately for the flea population) female fleas tend to live longer than males - there are also more females than males. If a dog or cat is left to groom itself normally (and cats groom more thoroughly than dogs on the whole), many adult fleas will also be dislodged or swallowed naturally. However, if for any reason, a cat or dog is unable to groom itself - it may be ill for example - then the owner should groom it more frequently than usual, to mirror the pet's natural methods of flea control.
Fleas are the most common cause of skin disease in cats and dogs. Many vets confirm that up to two thirds of their time, especially in the summer, is spent treating flea-related conditions in pets.
Places such as tile floors are less likely to support development as they can be more easily kept clean. Well traveled hallways are also less likely 'hot spots' as the constant vibrations and air currents will ensure that fleas hatch quickly and can find a suitable host in a shorter time, thereby not lurking around for long.
Start your flea control offensive inside the house but ensure that you regularly vacuum chair covers and rugs, and any bedding used by your pet. Regular washing of bed linen and loose covers also sorts the problem out.
Vacuuming, especially if you have a 'beater bar', will remove some flea eggs and a certain percentage of flea larvae (although spines on the larvae's bodies can make them difficult to dislodge). The vibrations will also stimulate adult fleas to emerge from their cocoons but make sure that you empty out the bag every time you vaccuum otherwise the fleas will simply continue their life cycle inside it.
Remember to vacuum down the sides and underneath sofas and chairs and in dark corners. Flea larvae move away from the light and so, although most larvae will be found where the flea eggs are deposited, they can travel up to half a metre away from these areas.
Environmental flea sprays, containing long acting insecticides or insect growth regulators are useful and s hould be used according to the manufacturer's instructions. Fleas in their larval stages, hiding deep down in carpet fibres and in dark nooks and crannies, are much more difficult to get at with conventional sprays and the silken cocoons spun during the pupating stages are impervious to them.
Unlike larvae, adults move upwards towards light as this makes it easier for them to locate a host. It also means that they are more easily affected by household insecticidal sprays.
Outside the house, mow or clip the areas under bushes and remove leaves and other debris to allow these places to dry out. Try and keep piles of refuse or wood to a minimum and keep them as dry as possible.
Dr John Maunder of the Medical Entomology Department at the University of Cambridge,
is one of Britain's leading flea experts. He has this to say about the successful treatment of fleas:
'Flea control is best directed at the free- living stages, which is the one thing that until now has been difficult
to do. Insect growth regulators are a new feature in the flea control area and a new compound, lufenuron, a
systemic insect development inhibitor seems to provide the answer. It is the effect of lufenuron against the
immature stages of the fleas which is the most effective plan of attack.'
The following offers advice on the most effective means of attack - from taking preventative measures to a void a flea problem altogether to tackling a severe infestation of both pets and household.
Make sure that you strictly follow the manufacturer's instructions for any treatment you decide to use - failure to do this may not only be dangerous but will usually result in the treatment being ineffective.
Use of an insect growth inhibitor before a flea problem begins is therefore the best way to counteract the chances of infestation. Insect growth inhibitors, such as Program from Ciba Animal Health, are available from veterinary surgeons and are simply given to your dog or cat, once a month, in their food. Safe enough for use on puppies, kittens and pregnant pets, the use of Program will ensure ensure that any adult fleas which do manage to get to your pet, will lay eggs which are unable to hatch, thereby stopping the life cycle in its tracks.
Monthly use throughout the year will keep your home from becoming a 'home from home' for these unwelcome 'flea loaders'!
Check for any new 'hot spots', groom pets, wash their bedding and any loose covers, and vacuum regularly - clever they might be but with a little thought and advance planning, fleas can be beaten - for good!
Could this be because you thought winter would see off the flea problem and so stopped any treatment of your pet? Probably!
Start your pet on lufenuron and, at the same time, use an 'adulticide' flea treatment on the pet until the infestation is under control. This will have the effect of killing off as many adult fleas as quickly as possible whilst rendering any that have the chance to feed off the pet infertile and unable to continue the life cycle.
Insecticides for use on pets come in many types, presentations and duration of action. All on-animal insecticides are licensed and are therefore safe to use as directed. The choice of preparation tends to be due to either vet or pet owner preference. Sprays or low volume 'spot-on' formulations are the most popular compared with powders or collars.
In the past the on-animal insecticide approach to flea control has had the most attention. However, as knowledge of flea biology has increased, the realisation that the key to effective flea control was to effectively break the life cycle rather than just kill the 5% of adults on the pet has focused the attention on the newer insect development inhibitor approach.
All insectides have the same weakness in that efficacy gradually wanes and at some stage viable flea eggs are once again dropped off into the environment to start the life cycle again. Owners are reluctant to continually coat their pets with insecticides, however the concept of the continuous protection that can be given using a product that acts only on insect tissue has found favour and is now a market leader in flea control.
Keep up the regular washing of your pet's bedding and clean and vacuum around the house. Continue to use lufenuron monthly to prevent the problem happening again.
The best method for an emergency like this is a three-pronged battle plan: start your pet on lufenuron, to ensure that any new flea eggs are infertile when they are laid. This is the beginning of the end of the infestation.
Use an adulticide on the pet to help rid it of as many adult fleas as quickly as possible. At the same time, use an environmental spray treatment around the house. Pay particular attention to the hot spots where the pet frequently goes. Continue to regularly wash bedding, and clean and vacuum clean.
In cases of severe infestation, don't be discouraged if it takes a couple of months or longer to rid the pet and house completely - fleas are incredibly tenacious but they will disappear eventually.
The most important piece of advice to remember is don't leave it too late again! Just because you can't see fleas jumping, it doesn't mean they are not there. If you have a pet, always assume that the fleas are lying in wait and treat them accordingly. The monthly use of an insect development inhibitor throughout the year will ensure that, when the summer arrives next year, you will have peace of mind that your house will no longer be a sanctuary to fleas - the flea explosion won't even be a damp squib!
If you have any queries about the use of the product Program mentioned in the article then contact Ciba Animal Health on 0345 573912 9am to 6pm Mon-Friday (UK only)
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All pages copyright © Priory Lodge Education Ltd 1994-2000.