The Flea

Adult fleas are about ¹⁄₁₆ to ¹⁄₈ inch long, dark reddish-brown, wingless, hard-bodied (difficult to crush between fingers), have three pairs of legs (hind legs enlarged enabling jumping) and are flattened vertically or side to side (bluegill or sunfish-like) allowing easy movement between the hair, fur or feathers of the host. Fleas are excellent jumpers, leaping vertically up to seven inches and horizontally thirteen inches. An equivalent hop for a human would be 250 feet vertically and 450 feet horizontally.

They have piercing-sucking mouthparts and spines on the body projecting backward. Also, there is a row of spines on the face known as a genal comb. Spine I (first outer spine) is shorter than Spine II (next inner spine) in dog fleas. Both spines are about the same length in the cat flea. The rabbit flea has a vertical genal comb with blunt spines. The genal comb is absent in both rat fleas. Eggs are smooth, oval and white. Larvae are ¼ inch long, slender, straw-colored, brown headed, wormlike, bristly-haired creatures (13 body segments), that are legless, have chewing mouthparts, are active, and avoid light. Pupae are enclosed in silken cocoons covered with particles of debris.