How does the largest louse look? - briefly
The largest known louse measures roughly 4–5 mm, featuring a broad, flattened, reddish‑brown body and strong, clawed legs adapted for gripping host hair. Its head carries conspicuous antennae and robust chewing mouthparts.
How does the largest louse look? - in detail
The largest known species of chewing louse, Haematopinus suis (the hog louse), reaches lengths of 5–6 mm, making it the biggest representative among the order Phthiraptera. Its body is elongated and dorsoventrally flattened, facilitating movement through the host’s hair. The exoskeleton is sclerotized, giving a smooth, glossy appearance. Dorsal coloration ranges from reddish‑brown to dark brown, often with a slightly lighter ventral surface.
The head is small, equipped with a pair of compound eyes and short, multi‑segmented antennae. Mouthparts form a piercing‑sucking apparatus: a slender labrum, robust mandibles, and a stylet that penetrates the host’s skin to ingest blood. The thorax bears three pairs of legs, each leg ending in a pair of curved claws that grasp hair shafts securely. Legs are relatively long compared to body size, enhancing stability on coarse hair.
Key morphological details include:
- Body segmentation: distinct prothorax, mesothorax, and metathorax, followed by an abdomen composed of nine visible tergites.
- Spiracles: located laterally on the abdominal segments, each with a simple slit opening for respiration.
- Setae: fine, short hairs scattered across the dorsal surface, providing sensory input.
- Genitalia: males possess a median gonopore near the posterior abdomen; females exhibit an ovipositor adapted for egg deposition on hair shafts.
Overall, the hog louse presents a compact, robust form optimized for ectoparasitic life, distinguished by its size, dark glossy exoskeleton, and specialized feeding and attachment structures.