Note: Information is dated. Do not rely on it.Flea. An insect of the order Siphonaptera, characterized by the absence of true wings, in place of which are minute scales believed to be aborted wings. The mouth parts are adapted for biting and sucking. All the species of the genus are very similar to the common flea. It has two single eyes or ocelli and six feet; the feelers are like threads. The flea is remarkable for its agility, leaping to a surprising distance, and its bite is very troublesome.