They are 1.5-4 mm long, dark reddish-brown in color and wingless. Females lay up to 50 eggs per day and about 600 in total during their lifetime. At the larval stage, they do not feed on blood. Adult fleas can jump a distance of up to 30 cm.
They thrive at temperatures between 20-25 °C, while their life cycle is 30-75 days.
Fleas are dangerous insects, as they attack humans, cats, dogs, rabbits, poultry, mice to feed on blood and their bite is quite painful because they sink all their spiny head into the skin.
They are carriers of typhoid diseases and the plague bacterium.