The adult flea is 2-7mm long and brownish in colour. Their bodies are compressed from side to side enabling them to move quickly through hairs and they have relatively large hind limbs which are used for jumping. The three most common species are The Cat Flea (Ctenocephalides felis), The Dog Flea (Ctenocephalides canis) and The Human Flea (Pulex irritans )
All fleas live exclusively as parasites on warm blooded animals and although they have a preferred host, normally mammals, both the cat and dog flea can also be found on and feed from other animals and man. As well as being found on the host, fleas can frequently be found in the host’s bedding. Cat fleas are by far the most common accounting for 75% of all flea infestations. The flea population reaches its peak in September and is a particular problem in areas of high population density.
In the UK fleas are not generally responsible for the spread of infection but do inflict on their host unpleasant bites. Flea bites will be seen as a tiny dark red spot surrounded by a reddened area. The bite will remain irritating for one to two days and in some cases may lead to hypersensitivity.
Flea eggs are small, oval shaped and pearl white in colour and are laid indiscriminately in the fur or feathers of the host or in its bedding or resting material. The eggs hatch in about one week into white thread-like larvae. The larvae thrive in dark, humid places such as carpets and animal bedding.
After two or three weeks when they are fully grown the larvae spin a cocoon and pupate. The adult usually emerges within seven weeks but can remain as a pupa throughout the winter only emerging when triggered by the movement of a suitable host. The complete life cycle will normally last four weeks but may take longer at low temperatures.