Although we regard it primarily as a pest of human beings it often occurs very abundantly on cats, dogs, mice and rats as well as on some wild mammals such as badgers, foxes and others and has occasionally been found on birds. Most entomologists regard the fleas commonly found on cats and dogs as belonging to one species Ctenocephalus canis.
No carpet was used and being summer only a few rugs were placed on the floors. A part of the household consisted of a collie dog and three Persian cats. Very soon the fleas appeared, the dog and cat flea, Ctenocephalus canis. I did not count them and I can't say whether they numbered a million or only a hundred thousand.
Others believe them to be distinct species and call the cat flea Ctenocephalus felis. So far as our personal comfort and safety is concerned it makes but little difference to us whether the flea that bites us is called canis or felis for they both look very much alike, and act alike and the bite of one hurts just as much as the bite of the other.