How do lice and fleas bite? - briefly
Lice pierce the epidermis with their mandibles and feed by sucking blood directly from the wound. Fleas penetrate the skin using a spined proboscis, inject anticoagulant saliva, and then draw blood.
How do lice and fleas bite? - in detail
Lice and fleas are hematophagous ectoparasites that obtain nutrients by piercing the skin of their hosts and ingesting blood. Their feeding mechanisms differ markedly because of distinct mouthpart morphology and behavioral adaptations.
Lice possess chewing‑type mandibles that are modified into sharp, serrated blades. The feeding process proceeds as follows:
- The insect grasps hair shafts with its claws, stabilizing its position on the host.
- Mandibles puncture the epidermis, creating a small wound.
- Salivary glands secrete anticoagulant enzymes that prevent clotting.
- The insect scrapes epidermal tissue and draws a mixture of blood and tissue fluid into the foregut.
The bite produces a localized erythema that may develop into a papule. Saliva contains proteases that facilitate tissue breakdown and prolong feeding, typically lasting several minutes.
Fleas employ a piercing‑sucking proboscis composed of a rigid labrum and flexible stylet bundle. Their feeding sequence includes:
- Jumping onto the host and anchoring with hind legs.
- Inserting the stylet pair through the epidermis, navigating between cells to reach a capillary.
- Injecting saliva that contains anticoagulants, anti‑inflammatory compounds, and anesthetic peptides.
- Drawing pure blood through the central canal of the proboscis into the midgut.
A flea bite often appears as a small, raised, red spot with a central puncture. The injection of anesthetic agents reduces immediate pain, allowing the insect to feed for 5–10 minutes before detaching.
Key anatomical distinctions:
- Lice: mandibles → mechanical tissue disruption; saliva rich in proteolytic enzymes.
- Fleas: stylet proboscis → precise vascular access; saliva contains anticoagulant, anti‑inflammatory, and anesthetic factors.
Both parasites transmit pathogens during feeding; the composition of their saliva influences host immune response and the likelihood of secondary infection.