Fleas are small, wingless insects that feed on the blood of mammals and birds. They are typically 1-3 mm in length and have a reddish-brown color. Fleas have a flattened body that allows them to move easily through fur or feathers. They have six legs, with the hind legs being longer and stronger than the front legs. Fleas have a pair of antennae on their head and a pair of sharp mandibles that they use to pierce the skin of their host and feed on their blood.
Fleas are a common pest and can cause a variety of health problems for both humans and animals. They can transmit diseases such as typhus, murine typhus, and plague. Fleas can also cause skin irritation and allergic reactions. In severe cases, flea infestations can lead to anemia and even death.