How does a flea bite a person? - briefly
A flea uses its needle‑like mouthparts to pierce the skin, injects saliva that contains anticoagulants, and then draws blood. The bite typically produces a tiny, itchy papule that may become a red spot.
How does a flea bite a person? - in detail
Fleas attach to the host using specialized mouthparts called the proboscis. The proboscis consists of a slender, needle‑like labrum that penetrates the epidermis, a serrated maxilla that cuts tissue, and a stylet that delivers saliva. The process unfolds in several stages:
- The flea lands on exposed skin and detects warmth and carbon‑dioxide, prompting movement toward a suitable feeding site.
- The labrum pierces the outer skin layer, creating a minute wound typically 0.1–0.2 mm in diameter.
- The maxilla’s serrations enlarge the incision, allowing the stylet to reach the superficial dermal blood vessels.
- Saliva, containing anticoagulants such as apyrase and anticoagulant proteins, is injected to prevent clotting and to facilitate blood flow.
- Blood is drawn up through the stylet by capillary action and stored in the flea’s enlarged crop for later digestion.
During feeding, the flea’s sensory receptors monitor pressure and chemical cues, adjusting the depth of penetration to avoid excessive tissue damage. The bite remains invisible to the host until the injected saliva triggers a localized immune response, producing a pruritic, erythematous papule. Repeated bites may lead to secondary infection if the skin is scratched.
Flea feeding duration averages 5–10 minutes per attachment, after which the insect disengages and searches for another site. The entire mechanism enables rapid blood acquisition while minimizing detection by the host.