The locomotory patterns of fleas reflect their way of life as parasites of fur- or feather-covered hosts. Fleas are able to move through dense host pelage and withstand the host's anti-parasitic grooming. They also are able to jump, to move through the substrate of a host's burrow or nest and to move on vertical surfaces (e.g. fleas parasitic on bats). Here, I briefly review the morphological and physiological aspects of flea locomotory features that facilitate the successful exploitation of hosts.

On-host locomotion

Flea locomotion in host pelage or feathers differs from that of other mammal and bird ectoparasites. For example, Nycteribiidae (bat flies) have a compressed dorsoventral body and long, spider-like legs (Dick & Patterson, 2006). They are capable of fast sliding movements above the fur of the host. In contrast, the laterally compressed body, high and narrow head capsule and flexible joints of the thorax and abdomen of fleas allow them to move through host pelage by dividing the hair during forward movement.

The flea thorax consists of three separate modified segments (pro-, meso- and metathorax), whereas the abdomen consists of 10 segments. The posterior margins of each segment form collars that overlie the anterior margins of the next segment. As a result, these segments are able to ‘squeeze’ into each other. In contrast to most winged insects, separation of the mesothorax and metathorax in fleas leads to the absence of a pterothorax which is characteristic of other holometabolous insects.