How to know if it is a louse? - briefly
A louse is a small, wing‑less, cigar‑shaped insect (approximately 2–4 mm) that moves rapidly through hair and leaves nits firmly attached to the hair shaft close to the scalp. Persistent itching together with visible crawling insects confirms its presence.
How to know if it is a louse? - in detail
Lice are small, wingless insects that live on mammals and birds. Identification relies on size, body shape, and location on the host.
Typical adult body length ranges from 1 mm to 4 mm. The head is visibly wider than the thorax, with a compact, flattened profile that allows movement through hair or feathers. Antennae are short, usually fewer than five segments, and the legs end in claws adapted for grasping shafts. Mouthparts are piercing‑sucking, designed to feed on blood or skin secretions.
Key visual cues include:
- Uniformly brown or gray coloration, lacking the patterned wings of flies.
- Six legs, each bearing a curved claw; the hind legs are often longer, facilitating clinging to host hairs.
- Absence of a distinct abdomen segmentation visible in many beetles.
- Presence of a ventral “posterior” that may appear slightly swollen in females carrying eggs (nits).
Inspection techniques:
- Part hair or feathers close to the scalp or skin with a fine‑toothed comb.
- Examine combed material under magnification (10–40×) to detect live insects, eggs, or shed skins.
- Look for nits attached firmly to shafts within 1 mm of the scalp; they are oval, cemented, and cannot be brushed away easily.
- Observe for itching or irritation localized where insects congregate, typically at the nape, behind ears, or in the pubic region for humans.
Differentiation from similar arthropods:
- Fleas are larger (2–4 mm), possess jumping legs, and have a laterally compressed body.
- Mites are smaller (0.2–0.5 mm), have a more rounded shape, and often leave fine, moving specks rather than solid bodies.
- Ticks are much larger (several millimeters), have a hard shield (scutum), and attach for prolonged periods rather than moving continuously.
Laboratory confirmation may involve:
- Collecting specimens in ethanol for microscopic examination.
- Identifying species by the arrangement of setae on the head and thorax.
- Using DNA barcoding when morphological features are ambiguous.
Accurate recognition depends on careful visual inspection, awareness of typical dimensions and morphology, and distinguishing characteristics from other ectoparasites.