What does a bed bug look like and what are its dimensions? - briefly
A bed bug is a tiny, oval, reddish‑brown insect that flattens when unfed and swells after a blood meal. Adults are approximately 4–5 mm long and 2–3 mm wide, expanding to about 6–7 mm when fully engorged.
What does a bed bug look like and what are its dimensions? - in detail
A bed bug is a wingless, hematophagous insect belonging to the family Cimicidae. Its body is dorsoventrally flattened and oval, resembling a small apple seed. The exoskeleton is smooth, covered with fine, pale hairs that give a matte appearance. Color varies from light brown after a molt to deep reddish‑brown after feeding, due to ingested blood. The head is concealed beneath the pronotum, and the antennae consist of four short, segmented filaments. Six legs emerge from the thorax, each ending in a clawed tarsus adapted for gripping fabric and skin. The mouthparts form a slender, elongated proboscis used to pierce host skin and extract blood.
Typical size ranges are:
- Adult: length 4.5–5.5 mm, width 1.5–3 mm, thickness 1 mm when unfed.
- Nymphal stages (instars 1–5): length 1.5 mm (first instar) to 4 mm (fifth instar), proportionally narrower.
- After a blood meal, an adult can expand to near 7 mm in length and appear swollen and darker.
The insect’s exoskeleton is semi‑rigid, allowing it to flatten further when hiding in crevices. The ventral surface bears a pair of spiracles for respiration. These morphological traits enable the bug to move quickly across fabrics, hide in mattress seams, and survive without feeding for several months.