How do bed lice look? - briefly
Bed lice are tiny, wingless insects measuring roughly 1–2 mm in length, with a flattened, oval body. Their coloration ranges from reddish‑brown to dark brown, and their legs end in claw‑like tarsi for clinging to fabrics.
How do bed lice look? - in detail
Bed lice are small, wingless insects that resemble other hematophagous arthropods. Adults measure 1.5–4 mm in length, with a flattened, oval body that allows them to move easily through fabric and bedding. The exoskeleton is a pale, reddish‑brown hue that darkens after a blood meal, giving the insect a slightly engorged, bluish appearance. Six legs emerge from the thorax, each ending in a pair of claws adapted for gripping fibers. Antennae are short, segmented, and concealed beneath the head when the insect is at rest.
The head bears a pair of compound eyes and a proboscis designed for piercing skin and sucking blood. The mouthparts are elongated, needle‑like, and capable of remaining hidden within the exoskeleton until feeding. The abdomen is segmented, with visible dorsal plates (tergites) that may show faint, irregular markings in mature specimens.
Nymphal stages differ in size and coloration:
- First‑instar nymphs: 0.5 mm, translucent, almost invisible against light fabrics.
- Second‑instar: 0.8 mm, pale yellow‑brown, still translucent.
- Third‑instar: 1.2 mm, darker brown, more opaque.
- Fourth‑instar: 1.5 mm, deep reddish‑brown, approaching adult coloration.
Females are generally larger than males, especially after engorgement, and may appear more swollen due to the presence of eggs. Both sexes possess a pair of sensory hairs on the dorsal surface that aid in navigation through bedding.
When unfed, the insects are flat and inconspicuous; after feeding, their bodies expand up to twice their original size, becoming more rounded and visibly darker. Their movement is slow but deliberate, and they often hide in seams, mattress tufts, and creases where the fabric folds create protected microhabitats.