How do rat fleas bite? - briefly
Rat fleas use their piercing‑sucking mouthparts to breach the skin and inject saliva that contains anticoagulants, allowing them to draw blood. The resulting bite is a tiny, red, itchy puncture.
How do rat fleas bite? - in detail
Rat fleas (Ctenocephalides spp.) attach to a host by sensing body heat, carbon‑dioxide, and movement. Once contact is made, the insect walks toward a suitable skin area, usually near the base of the hair shaft where the cuticle is thin.
The flea’s mouthparts consist of a pair of piercing stylets enclosed within a sheathed structure. The longer stylet penetrates the epidermis, while the shorter one acts as a canal for saliva. Muscular action drives the stylets forward, creating a puncture approximately 0.2 mm deep. Saliva, containing anticoagulant proteins such as apyrase, is injected to prevent clotting and to keep the blood pool fluid.
After the puncture, the flea uses a sucking tube to draw blood into its foregut. The ingestion rate averages 0.2–0.5 µL per feeding bout, lasting 2–5 minutes. Blood is stored in the midgut, where digestive enzymes break down proteins. The flea then withdraws the stylets and releases residual saliva onto the skin surface.
Key points of the feeding cycle:
- Host detection via thermal and chemical cues.
- Navigation to a thin‑skinned region.
- Stylet insertion and saliva injection.
- Blood uptake through the sucking tube.
- Withdrawal of mouthparts and completion of the bite.
During the bite, the flea’s saliva can transmit pathogens such as Yersinia pestis (plague) or Rickettsia spp. The bite itself is typically painless because the flea’s mandibles do not cut tissue; the sensation arises only after the feeding site becomes inflamed from the immune response to saliva proteins.
Environmental conditions influence feeding frequency. High humidity and moderate temperatures (20‑30 °C) increase flea activity, leading to more frequent bites. Conversely, low humidity reduces survival and feeding propensity.
In summary, rat fleas employ a specialized piercing‑sucking apparatus, inject anticoagulant saliva, and extract a small volume of blood in a rapid, minimally traumatic event that can serve as a vector for disease.