flea

Flea refers to any of numerous small, wingless parasitic insects in the order Siphonaptera. Fleas are ectoparasites of mammals and birds, feeding on blood. They have laterally compressed bodies, short antennae, and large hind legs for jumping.

Common species on domestic animals include the cat flea (Ctenocephalides felis) and dog flea (Ctenocephalides canis). The human flea (Pulex irritans) and the oriental rat flea (Xenopsylla cheopis) are also significant. Fleas are typically 1.5–4 mm long and range in color from brown to reddish.

Life cycle: fleas undergo complete metamorphosis with egg, larva, pupa, and adult. Eggs are laid on hosts or in the environment and hatch into larvae that feed on organic debris. Pupae develop in cocoons and may remain dormant until conditions or host cues trigger emergence.

Ecology and impact: fleas spend much of their life off-host, bite hosts, cause itching and allergic reactions, and can cause anemia in heavy infestations. They are important disease vectors, notably of Yersinia pestis (plague) by Xenopsylla cheopis and Rickettsia typhi (murine typhus), and can transmit Dipylidium caninum when pets or people ingest infected fleas.

Control: management combines treating pets with antiparasitic products and reducing environmental stages through cleaning, vacuuming, washing, and targeted insecticides. Effective control relies on integrated pest management and ongoing monitoring.