Fleas are ectoparasitic insects, meaning they live on the outside of a host animal. They feed on the blood of mammals and birds. It’s estimated that there are around 2,500 species of flea in the world.
We get three types of flea in the UK. The most common is the cat flea Ctenocephalides felis. Less often, we get dog fleas Ctenocephalides canis. While rare, we do occasionally get human flea Pulex irritans infestations.
Risk to people
In the UK at least, fleas do not commonly spread disease.
Although fleas do not pose a direct health risk, flea bites can cause intense irritation and itching to pets and humans alike.
The most problematic aspect of a flea bite on humans is the infection which can be caused by prolonged itching when left untreated.
Flea bites have been known to cause skin complaints, and can also exacerbate respiratory illnesses and cause complications.
Risk to pets
If your pet has fleas, it will suffer from a great deal of discomfort and could also have an allergic reaction to the flea’s saliva.
Lengthy periods of infestation can cause your pet to develop anemia from the loss of blood, although this is rare. (See Fleas on pets below.)
Types of flea in the UK
The most common species of flea in the UK is the Cat flea Ctenocephalides felis. They are an extremely common pest whose primary host is domestic cats, but are known for readily biting humans and dogs too.
That’s right - just because it’s called a Cat flea, it doesn’t mean the pest won’t try and bite people too!
The Dog flea Ctenocephalides canis can also use a variety of mammals as a host, but primarily targets dogs and cats.
Other types of flea to be aware of are; the Bird flea Ceratophyllus gallinae and Human flea Pulex irritans.
The Bird flea only lives for a short time but is an impressive breeder, multiplying in great numbers in habitats such as hen houses.
Finally there are Human fleas, which are now rare in the UK. They are a known carrier of plague Yersinia pestis.
Habitat: how fleas choose a home
Fleas can live on any warm-blooded animal but are often found to be living on humans, domestic animals and rodents.
When not feeding on a host, fleas are mainly active in communal rooms, places where pets sleep and wherever there is most activity.
Fleas and their eggs can be commonly found in soft furnishings which provide plenty of insulation, such as carpets, pet bedding, clothes and upholstered furniture.
If you have an active infestation, you may see fleas jumping in your carpet and furniture.
Where do fleas come from?
It’s not always obvious where they’ve come from, as even homes without pets can get flea infestations.
Around 95% of flea eggs, larvae and pupae live in the environment, not on pets.
As flea eggs can survive dormant for long periods of time, sometimes up to 18 months, it’s possible that the infestation was a problem before you even moved into your current home!
If you have pets, they can pick up fleas from other animals or places and give them a ride home.
And although it’s less common, so can humans: the fleas will hitch a ride on your clothes, your skin or hair.
People usually feel ashamed to find out they have a flea infestation, as fleas are often associated with dirty environments.
But this is a common misconception - fleas are not picky!
Although a home or business that isn’t vacuumed or cleaned is more likely to provide a better environment for fleas to thrive, they will also infest clean places in their search for a warm-blooded host.
Either way, it is crucial to solve a flea infestation without hesitation as they can quickly get out of control.
Six tell-tale signs that fleas are about
- Pets constantly scratching, licking or biting themselves may be the first sign
- Seeing fleas or flea droppings in the coat of your pet (easily spotted in light-coloured animals by brushing back the hair, in dark coated breeds it may be better to comb the animal over a sheet of paper)
- The identity of the black specks may be confirmed by adding a few drops of water: if they turn red, your pet has fleas!
- Bites on you or other members of the household, usually around ankles and legs
- If you have been holding or stroking a pet, you may find bites on your arms
- And the most obvious sign of a flea infestation? Seeing them! When they aren’t busy leeching our AB positive, fleas can often be spotted jumping around on soft furnishings.
Flea biology and behaviour
Appearance differs only very slightly for different types of flea, and often only trained professionals are able to spot the difference under a microscope.
As a group, adult fleas are wingless, flattened laterally (enabling them to move easily through fur) and vary in colour from grey to dark mahogany.
Most species have backwardly directed spines, which are designed to help them grip onto their host.
Adult Dog fleas are on average 2mm in size and brownish-black in colour (appearing to be more reddish-black after a blood meal).
Adult Cat fleas are generally bigger, on average 3mm in size.
Depending on environmental conditions, these stages can take between two weeks and eight months to complete.
Female fleas can live up to two years, during which time they are able to lay around 1500 eggs.
The females must first take a ‘blood meal’ from an infested animal, after which they lay their eggs.
The eggs drop onto the floor and surrounding furnishings, and after several days will develop into larvae.
Critically, they can't lay viable eggs in the absence of the host animal blood meal.
When fully grown the larvae spin well camouflaged, silken cocoons.
Once fully developed the adult waits within the cocoon until it detects the vibrations caused by a person or animal.
It can also detect pressure, heat, noise, or carbon dioxide from potential hosts.
Only then does it emerge. The complete life cycle takes about a month in the summer.
A marvellous feat which only appears to be rivalled in the animal kingdom by froghopper insects (yeah, we’d never heard of them either).
Fleas do this by using their hind legs as multi-jointed levers, gripping the ground for traction before crouching down and using their muscles to store energy.
When this energy is released, it acts almost like a bow and arrow, propelling the flea rapidly.
A flea’s ability to jump great distances is what enables it to switch hosts, since they are without wings.
Additionally, their legs end in strong claws which help them grip onto their host.
This, combined with their hardened shells, are adaptations which enable them to withstand intense scratching and attempts to remove them.
Contact Krypton Environmental today for a fast and effective flea eradication service 01793 780600