Fleas are very small, wingless, laterally flattened insects of the order Siphonaptera. They’re best known for being external parasites on mammals and occasionally birds. Adult fleas live in the fur or feathers of their hosts, feeding on their blood to survive and reproduce. While fleas do feed off humans, more common host animals include rodents, dogs and cats. The “human” flea, Pulex irritans, actually attacks a broad range of mammal species, and the same is true of most flea species that bite humans. About 2,000 species and subspecies are known worldwide, with at least 127 found in Canada, most of them in British Columbia and Alberta.