What do bed lice and head lice look like? - briefly
Bed lice are oval, reddish‑brown insects about 4–5 mm long, dorsally flattened and most noticeable after feeding. Head lice are smaller, 2–3 mm long, tan to gray, with an elongated body and three pairs of clawed legs that cling to hair shafts.
What do bed lice and head lice look like? - in detail
Bed lice (Cimex lectularius) are small, oval‑shaped insects about 4–5 mm long. Their bodies are dorsally flattened, facilitating movement within fabric seams. The exoskeleton is a matte, reddish‑brown color that darkens after feeding. Six legs emerge from the thorax, each ending in a claw that grips fibers. Antennae are short, segmented, and hidden beneath the head capsule. Adult females are slightly larger than males and carry a visible abdominal swelling when engorged with blood. Nymphs resemble miniature adults, undergoing three molts before reaching maturity; each instar appears lighter in color and less sclerotized.
Head lice (Pediculus humanus capitis) measure 2–3 mm in length, making them noticeably smaller than bed lice. Their bodies are elongated, cylindrical, and covered with a transparent, waxy cuticle that imparts a gray‑white hue. The head is broader than the thorax, bearing a pair of short, forward‑pointing antennae and three pairs of legs, each equipped with a claw adapted for grasping hair shafts. Legs are longer relative to body size, enabling rapid crawling on the scalp. Eggs (nits) are oval, 0.8 mm long, firmly attached to hair strands near the scalp with a cement‑like substance; they appear white or yellowish and are often visible at the base of hair.
Key visual differences:
- Size: bed lice 4–5 mm; head lice 2–3 mm.
- Body shape: bed lice oval and dorsally flattened; head lice elongated and cylindrical.
- Color: bed lice reddish‑brown, darkening after a blood meal; head lice gray‑white, translucent.
- Habitat: bed lice reside in mattress seams, upholstery, and crevices; head lice remain on the scalp, moving through hair.
- Legs: bed lice have short legs suited for crawling on fabrics; head lice possess longer legs for navigating hair shafts.
- Eggs: bed‑lice eggs are laid in fabric folds and are pale; head‑lice nits are cemented to hair near the scalp and appear white.
Both species are wingless, lack eyes, and feed exclusively on human blood. Their mouthparts are adapted for piercing skin and extracting blood, resulting in puncture marks that may appear as tiny red dots. Recognizing these morphological traits aids accurate identification and appropriate treatment.