What do human fleas look like? - briefly
Human fleas are tiny, wingless insects about 2–4 mm long, dark brown to reddish‑brown, laterally flattened, and covered with short bristles; their hind legs end in a row of comb‑like spines used for jumping. They have a compact, rounded abdomen and lack visible wings or antennae segments beyond a short, stiff proboscis.
What do human fleas look like? - in detail
Human fleas are small, laterally flattened insects measuring approximately 1.5–3.5 mm in length. Their bodies are dark brown to reddish‑brown, becoming lighter toward the abdomen. The exoskeleton is smooth, lacking visible setae except for a few fine hairs near the legs.
The head is proportionally large, bearing compound eyes that appear as tiny dark spots. Two short antennae emerge from the anterior margin, each composed of six segments. Mouthparts are adapted for piercing and sucking, with a slender stylet that penetrates the host’s skin to ingest blood.
The thorax consists of three distinct segments, each bearing a pair of powerful legs. The hind legs are markedly longer, equipped with a resilin pad that stores elastic energy, enabling the flea’s characteristic jumps of up to 150 times its body length. Each leg ends in a pair of claws that grasp hair shafts or fabric fibers.
The abdomen is segmented into nine visible tergites, each bearing a row of fine bristles. Coloration darkens toward the posterior, and the abdomen expands after a blood meal, becoming visibly engorged. The dorsal surface is covered by a thin, waxy cuticle that reduces water loss.
Key morphological details:
- Size: 1.5–3.5 mm (adult); nymphs are 0.8–1.5 mm.
- Color: Dark brown to reddish‑brown; lighter posterior abdomen.
- Body shape: Laterally compressed, streamlined for movement through hair.
- Head: Large with compound eyes, six‑segmented antennae, piercing mouthparts.
- Legs: Three pairs; hind legs elongated with a resilin spring for jumping; terminal claws for grasping.
- Abdomen: Nine tergites, fine dorsal bristles, expands when fed.
- Cuticle: Thin, waxy, water‑resistant.
Eggs are oval, about 0.5 mm, white and non‑motile, deposited on the host’s clothing or bedding. Larvae are blind, cream‑colored, and C‑shaped, feeding on organic debris. Pupae develop in cocoons attached to fibers, remaining dormant until stimulated by vibrations or increased carbon‑dioxide levels. This life‑stage progression mirrors the adult’s morphology, with each stage exhibiting distinct size and coloration traits that aid identification.