Siphonaptera

Siphonaptera, commonly known as fleas, is an order of small, wingless, ectoparasitic insects that feed on the blood of mammals and birds. They are laterally compressed, enabling rapid movement through fur and feathers, and they possess strong hind legs for jumping. Adults have piercing-sucking mouthparts and generally range from about 1 to 4 mm in length. Many species bear comb-like structures of setae called ctenidia on the head and thorax, a feature used in identification and, in some cases, related to host association.

Fleas undergo complete metamorphosis, with life stages including egg, larva, pupa, and adult. Eggs are laid on the host or within the host environment; larvae feed on organic detritus, including dried blood and flea feces. Pupae develop inside protective cocoons and can remain dormant until host cues such as heat, carbon dioxide, or vibration indicate a nearby mammal or bird.

There are about 2,500 described flea species in roughly 15 families, distributed worldwide. Domestic species such as Xenopsylla cheopis (the rat flea), Ctenocephalides felis (the cat flea), and Pulex irritans (the human flea) are well known for their pest status and role as disease vectors.

Ecology and medical importance: fleas are vectors of several pathogens, most famously Yersinia pestis, the causative agent of plague, and Rickettsia typhi. They can also facilitate transmission of other bacteria, protozoa, and helminths, and may provoke allergic reactions in hosts.

Control and management focus on interrupting transmission by treating hosts and environments, regular grooming and monitoring of domestic animals, and the prudent use of insecticides as part of an integrated pest-management approach.