Adults cat fleas are about 1/8″ (2.5mm) long. The body is flat laterally from side to side and has not wings. Cat fleas are dark brown or black or red when full of blood.
Fleas can jump about 6″ vertically so they can easy hitch rides on legs and bodies of cats and kittens as well as humans.
Adults will begin to seek blood after the second day of birth but can live several months from the fat stored on their body. Cat fleas may transmit plague, and has very strong evidence that they may transmit typhus.
Females lay 4-8 eggs after each blood meal, which means females can lay over 400-500 eggs during their lifetime.