How does a scabies mite act? - briefly
The mite penetrates the outer skin layer, excavates a tunnel for egg deposition, and consumes epidermal tissue, causing intense itching. This activity provokes an inflammatory response that produces the typical rash and raises the risk of secondary infection.
How does a scabies mite act? - in detail
The scabies mite, Sarcoptes scabiei, penetrates the epidermis of a host to create a tunnel beneath the stratum corneum. The female initiates the burrow by inserting her front legs, then uses her chelicerae to rasp tissue and form a narrow, serpentine channel 2–5 mm long. Within this cavity she deposits 1–2 eggs each day; the eggs hatch into larvae after 3–4 days.
Larvae emerge with six legs and migrate to the surface of the skin. They climb onto a hair shaft, then crawl to a suitable site where they molt into eight‑legged nymphs. Nymphal development lasts 2–3 days before reaching adulthood. Adult males are smaller, remain on the skin surface, and locate females by following pheromonal cues. Mating occurs within the burrow; the male attaches to the female’s ventral side and transfers sperm while the female continues to lay eggs.
Feeding occurs through the tunnel walls. The mite inserts its mouthparts into the host’s epidermal cells, secreting proteolytic enzymes that liquefy cellular material. This exudate provides nutrition and simultaneously induces a localized inflammatory reaction. Continuous feeding and the presence of mite waste products provoke intense pruritus, especially at night.
Movement is limited to the immediate vicinity of the burrow. Adult females rarely exit the tunnel, whereas males and nymphs can traverse the skin surface to locate new sites. The mite’s locomotion relies on coordinated leg strokes and sensory hairs that detect temperature, humidity, and chemical signals.
Reproductive output is high: a single fertilized female can produce up to 30 eggs before dying, typically after 4–6 weeks. The life cycle, from egg to mature adult, completes in 10–14 days under optimal conditions, allowing rapid population expansion on a susceptible host.
Key behavioral stages:
- Burrowing: female creates a tunnel, deposits eggs.
- Hatching: larvae emerge, climb to hair shaft.
- Maturation: larvae molt to nymphs, then adults.
- Mating: male locates female via pheromones, transfers sperm.
- Feeding: enzyme‑mediated ingestion of epidermal tissue.
- Dispersal: males and nymphs move across skin to find fresh sites.
These actions enable the mite to establish infestation, sustain nutrition, and propagate within the host environment.