Are fleas insects?


Fleas are insects. Taxonomically, they’re classified under Animalia (kingdom), Arthropoda (phylum), Insecta (class) and Siphonaptera (order). Fleas are holometabolous insects, meaning they transition through four stages: Egg, larva, pupae, and adult.


Cat Flea Taxonomy
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Siphonaptera
Family: Pulicidae
Genus: Ctenocephalides
Species: C. felis

Flea taxonomy is based on the external morphology of adults, namely features of their head, thorax and abdomens. The first description of a flea species dates back to 1758.


Fleas belong to the Insecta class. They’re hematophagous insects, as both females and males sustain themselves on blood. Fleas go through complete metamorphosis (holometabolism), transitioning from eggs to larvae, to pupae, and finally to adults. Like all insects, fleas have six legs and three body segments. However, unlike most insects, they lack compound eyes.

Fleas don’t have wings. This is a common trait among ectoparasites. While fleas can’t fly, their ancestor could. Fleas are thought to descend from a two-winged insect similar to scorpionflies.


Fleas belong to Siphonaptera, a relatively small order of parasites of mammals and birds. Siphonaptera is a combination of the Greek words “siphon” and “aptera”, which literally translate to “tube” and “wingless”.

There are four infraorders of fleas: Pulicomorpha, Pygiopsyllomorpha, Hystrichopsyllomorpha, and Ceratophyllomorpha.


Within the infraorders, there are 18 families of fleas. Fleas of domestic and veterinary importance typically belong to the Pulicidae family, which is within the Pulicomorpha infraorder.


There are 242 genera and 97 subgenera of fleas. The most common genus found on dogs and cats is Ctenocephalides, which falls under the Pulicidae family. Another genus associated with humans and pets is Pulex, again in the Pulicidae family.


In 2005, Medvedev conducted The Catalogue of Life survey on Siphonaptera. He found 2005 species and 828 subspecies of fleas. However, some newly discovered species are absent from the database. 95% of these species parasitize mammals. The other 5% live on birds.

In the United States, only four species infest cats and dogs in large enough numbers to be considered significant. These are the cat flea (Ctenocephalides felis), dog flea (Ctenocephalides canis), human flea (Pulex irritans), and stickfast flea (Echidnophaga gallinacea).

Ctenocephalides felis felis, the cat flea, is the species most frequently discovered on domesticated dogs and cats. As a result, most research focuses on this species. The name ‘cat flea’ doesn’t imply all fleas on cats are the same species, or that the species is limited to cats. It’s simply the common name for C. felis.


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