Bedbugs: how do they bite? - briefly
They pierce the skin with a needle‑like proboscis, injecting saliva that contains anticoagulants and anesthetics, which initially causes a painless puncture that later turns itchy and inflamed. The resulting mark is usually a small, red, clustered spot often arranged in a linear pattern.
Bedbugs: how do they bite? - in detail
Bed bugs (Cimex lectularius) locate a host through heat, carbon‑dioxide, and body odours. When a suitable spot is identified, the insect climbs onto the skin and inserts its elongated, beak‑like proboscis into the epidermis. The proboscis consists of two interlocked stylets: one pierces the skin, the other delivers saliva.
Saliva contains anticoagulants, vasodilators, and anesthetic compounds. Anticoagulants prevent clot formation, allowing continuous blood flow. Vasodilators expand capillaries, increasing blood volume at the bite site. The anesthetic masks the intrusion, so most victims remain unaware until after feeding.
The feeding cycle proceeds as follows:
- Attachment – the bug secures itself with its claws and begins probing.
- Insertion – stylets penetrate to a depth of 0.2–0.3 mm, reaching a capillary.
- Salivation – a few microlitres of saliva are injected.
- Blood ingestion – the insect draws blood at a rate of 0.2 µL per minute, typically for 5–10 minutes.
- Detachment – the bug withdraws the proboscis and drops off the host.
During the process, the insect’s gut expands to accommodate the ingested blood, which is stored as a nutrient reservoir for later digestion. After feeding, the bug retreats to a harboring site, such as mattress seams or cracks in furniture, where it digests the meal over several days.
Reactions to the bite vary. The saliva’s proteins can trigger a delayed hypersensitivity response, producing a raised, erythematous wheal that may itch for days. In sensitised individuals, multiple bites can coalesce into linear or clustered lesions. The lack of immediate pain often leads to unnoticed infestations until skin reactions appear.
Understanding the anatomical specialization of the proboscis, the composition of the saliva, and the feeding timeline provides a comprehensive view of how these insects obtain blood from humans.