What do fleas look like in a human's head? - briefly
Fleas are tiny, dark‑brown insects about 1–3 mm long, laterally flattened, with powerful hind legs that enable rapid jumps. On a human scalp they may be mistaken for lice, but they lack the elongated, segmented appearance typical of head lice.
What do fleas look like in a human's head? - in detail
Fleas that manage to reach the scalp are small, laterally flattened insects measuring 1.5–3 mm in length. Their bodies consist of three main sections: head, thorax, and abdomen, each covered with a hard, dark exoskeleton that may appear brown, reddish‑brown, or black depending on the species and blood content. The head bears short, serrated antennae and large, compound eyes. Jumping legs emerge from the thorax; the hind legs are markedly longer and equipped with a spring‑like structure that enables rapid leaps of up to 150 mm.
The abdomen is segmented, expandable, and filled with blood after feeding. Engorged fleas swell to nearly double their original size, their abdomen becoming distended and more translucent, sometimes revealing a faint red hue through the cuticle. The legs end in tiny claws that grip hair shafts, allowing the parasite to move through dense scalp hair with ease.
Key visual characteristics:
- Size: 1.5–3 mm (unfed); up to 5 mm when engorged.
- Shape: dorsoventrally flattened, oval body.
- Color: dark brown to black; may appear reddish after a blood meal.
- Antennae: short, segmented, tucked against the head.
- Eyes: prominent compound eyes on the head.
- Legs: four pairs, with the hind pair markedly longer for jumping.
- Claws: minute, adapted to grasp individual hair strands.
When present on the scalp, fleas may be observed moving quickly between hair shafts, especially after the host is disturbed. Their rapid, erratic motion and sudden jumps distinguish them from lice, which move more slowly and lack the powerful hind legs. Engorged specimens may be seen as tiny, dark, balloon‑like specks embedded in hair, often causing itching and localized redness.