The flea is dark brown in color, wingless and possesses a laterally compressed chitineous abdomen (Soulsby 1982). The glossy surface of the body allows easy movement through hair and feathers (Urquhart et al. 1987). Compound eyes are absent, but some species have large or small simple eyes.

The legs are long, strong and adapted for leaping (Soulsby 1982). This can especially be seen in the third pair of legs which is much longer than the others (Urquhart et al. 1987) and muscular. In some species there are a number of large spines on the head and the thorax known as ‘combs’ or ctenidia. There may be a genal comb on the cheek (gena) and a pronotal comb on the posterior border of the first thoracic segment (Soulsby 1982). These combs or ctenidia belong to one of the three sets of characteristics in morphological taxonomy for identifying fleas, the so-called chateotaxy. Thoracic and leg structures and the structure of the male segment IX, the female sternite VII and the sperm holding organ (spermatheca) are the other two characterizing sets (Ménier and Beaucournu 1998).

As can be seen in ‘Origin and Distribution’ the species Ctenocephalides with its representatives C. felis felis and C. canis both have a worldwide distribution (Kalvelage and Münster 1991) and are the most important flea species parasitizing dogs and cats as man’s most wide-spread companions. Because of their genus similarities as well as their similar pattern of distribution and host spectrum, it is presumed that their biology does not show essential differences (Kalvelage and Münster 1991).