The cat flea is the cause of over three-quarters of all flea infestations. At 2-3mm long, it is often found in host bedding. Human and dog fleas are less common and the majority of human flea bites come from cat fleas. Adult fleas live off the blood of a variety of warm blooded-animals and birds. They are more nest than host specific and will feed on other animals in the absence of the preferred host. Fleas are carriers of both disease, such as typhus and bubonic plague, and also parasitic worms. Rodent fleas, in particular, are a prevalent source of murine typhus. In the UK, fleas are less of a concern from a disease perspective but their bites - visible as small deep-red spots within a reddened area - are painful and irritating and carry a social stigma. Fleas usually require a specific host, but will often feed on other animals if their preferred host is not available.
The life cycle of the flea usually takes place in the resting place of the host, eggs are laid by the female and are white and oval in shape and 0.5mm in length. The female may live for several months and lay 20-39 eggs per day.
The egg hatches in about a week, depending on the temperature. The small maggot like larvae search for food, feeding on organic remains, which may include undigested blood left by the adult. The larvae grow and when adult lie in wait for a passing host.
The pupa may remain dormant for up to 6 months. This complete cycle takes about a month if conditions are right. Adult fleas feed on blood and their bites can cause intense irritation at the bite site.
Fleas are flattened from side to side, a useful adaptation that enables them to move easily through the hairs or feathers of the host and they are well known for their jumping capability. Their colour varies from a light brown to almost black, but they are normally a reddish brown. Their body length ranges 1-8mm and are slightly oval in shape. Most fleas have a pair of small simple eyes, but some are blind, usually those that live underground. The flea, although winged, can jump great distances for its size, over 200 times its own body length.
As all development stages of the flea will be found in the habitat of the host, it is essential that this area be thoroughly treated. If there is any pet that might carry fleas then this animal must be treated using an insecticidal shampoo or powder obtainable from your veterinarian. The bedding of the animal must be cleaned regularly. If you use a vacuum then it is advisable to use a small amount of crawling insect powder inside the bag.
Where fleas are found in a property where there are no pets, then a careful search for old birds nests in the loft or eaves may prove worthwhile.