There are many species of fleas but in the UK it is cat and dog fleas that cause most problems. The main concern about fleas is usually the distress and discomfort that flea bites may cause you or your beloved pet.
Cat Flea
(Ctenocephalides felis)
Cat fleas are often unable to determine whether a host is suitable until it has been bitten. If it is deemed unsuitable, the flea soon drops off.
Appearance
Cat fleas are 3mm long wingless ticks, flattened from side to side with long legs enabling them to jump.
They have both genal and pronotal combs (ctenidia), differentiating them from most other fleas of domestic animals.
Life cycle and habits of the Cat Flea
Life Cycle
Fleas pass through four stages: eggs, larva, pupa, adult. The eggs are small and white. These stages combined vary from two weeks to eight months.
The adult flea is awakened by the detection of vibration of pet or human movement, pressure, heat, noise, or carbon dioxide for potential blood meals.
A cat flea cannot complete its life–cycle feeding only on human blood.
Habits
Cat fleas nest where the host is in its usual resting place, for example the cat basket. This is where the young often drop to mature.
Adult Dog fleas feed on the blood of dogs and cats, and they occasionally bite humans. It is a vector of the Dog Tapeworm, Dipylidium caninum, which can also affect humans.
Appearance
Adult is brownish black in colour, but appear reddish–black after a blood meal.
Adult dog fleas are 1 to 4 mm long. The legless larva is off–white and measures up to 5 mm long.
Life cycle and habits of the Dog Flea
Life Cycle
The fleas go through a four–stage life cycle: eggs, larvae, pupae, adult.
The larvae are longer than the adults and feed on particles of dry blood, excrement, and organic substances.
Habits
The body is laterally flattened, which allows it to move easily through an animal’s fur. Spines project backwards from the body of the flea, which help it to hold onto the host animal during grooming.
As they can jump approximately 6 inches, they can move from host to host. They can also infest garden lawns.
Human fleas are now less common in the UK, except for farming areas where they can survive on pigs, and then jump to humans. They will bite anywhere on the body and are associated with itchiness as fleas crawl over the skin.
Appearance
Fleas are black to brownish–black wingless insects. Adult fleas are 1 to 4 mm long.
They possess a long, fine proboscis which is used to pierce the skin of their host to feed on their blood.
Life cycle and habits of the Human Flea
Life Cycle
A female flea will lay 4 to 8 eggs after each blood meal, and can usually lay several hundred eggs during her adult life.
The smooth, oval light–coloured eggs measuring around 0.5 mm long, are deposited on, but not firmly attached to, the body, bedding, or nest of the host.
The adult generally emerges in a week or two after completing a larval and pupal stage, but under unfavourable conditions, the pupal period may be as long as a year.
Habits
Since they move from one host species to another, they present a risk of transmitting disease.
They are a known vector of Yersinia pestis (plague).
Human fleas can also be found on animals such as dogs, rats, pigs, deer and foxes.