How do human subcutaneous lice look? - briefly
Human subcutaneous lice are tiny, wing‑less insects about 1–2 mm long, with an elongated, translucent‑brown body. Their three pairs of short, clawed legs enable movement within the lower dermis or subcutaneous tissue.
How do human subcutaneous lice look? - in detail
Human subcutaneous lice are tiny, wing‑less insects that live beneath the skin of the host. Adults measure 0.2–0.4 mm in length, with a flattened, oval body adapted for navigating tight subdermal spaces. The cuticle is semi‑transparent, allowing the underlying hemolymph to impart a pale grayish‑white hue. Legs are short, stout, and end in claw‑like tarsi that grip the surrounding tissue. Each leg bears two to three setae, providing sensory feedback while the louse moves.
The head is reduced, bearing a pair of simple compound eyes and short antennae composed of three segments. Mouthparts form a piercing‑sucking stylet, capable of penetrating the epidermis to access blood vessels. The abdomen is segmented, with a visible dorsal median line separating the tergites. In the ventral region, the genital plate is distinct in adult females, appearing as a small, darkened sclerite.
Coloration varies with engorgement: unfed individuals retain the translucent background, whereas blood‑filled specimens appear darker, ranging from yellow‑brown to deep reddish tones. After a blood meal, the abdomen expands noticeably, increasing the overall size by up to 30 %. Nymphal stages resemble adults but are smaller (0.1–0.2 mm) and lack fully developed genital structures.
Key morphological features:
- Length: 0.2–0.4 mm (adult); 0.1–0.2 mm (nymph)
- Body shape: dorsoventrally flattened, oval
- Cuticle: semi‑transparent, pale gray‑white; darkens after feeding
- Legs: short, clawed, with sensory setae
- Mouthparts: piercing‑sucking stylet
- Eyes: simple compound, positioned laterally
- Antennae: three‑segmented, short
- Abdomen: segmented, expands after blood ingestion
These characteristics distinguish human subcutaneous lice from other ectoparasites, providing a reliable basis for microscopic identification.