What are Fleas? Fleas are small flightless, jumping and flat body insects. It has well developed hind legs for jumping. Fleas are external parasites of birds and mammals. They live off the blood of their hosts. An adult flea is 3mm long and generally brown. At the end of their legs, they have some tiny claws to help them attach to animals and other warm-blooded mammals. They sometimes … Continue reading Fleas