What do the male and female bedbug look like? - briefly
Male and female bedbugs are nearly identical in appearance: oval, reddish‑brown, about 4–5 mm long, with a flattened dorsal surface and visible antennae, though females are slightly larger and have a broader abdomen for egg development. After feeding, the female’s abdomen becomes noticeably swollen, distinguishing her from the male.
What do the male and female bedbug look like? - in detail
Bed bugs (Cimex lectularius) exhibit subtle sexual dimorphism that can be identified through careful observation of size, coloration, abdominal shape, and genital structures.
Males are typically slightly smaller, measuring 4.5–5.0 mm in length, with a more slender, tapered abdomen. The dorsal surface is uniformly reddish‑brown, while the ventral side shows a lighter, almost translucent hue. The pronotum (the shield‑like plate behind the head) bears a smooth margin and lacks conspicuous markings. Antennae consist of five elongated segments, each bearing fine sensory hairs. The most reliable male characteristic is the presence of a visible external genital capsule at the posterior end of the abdomen, appearing as a small, rounded protrusion.
Females are marginally larger, reaching 5.0–5.5 mm, and possess a broader, more rounded abdomen that expands when gravid. Their coloration mirrors that of the male—uniform reddish‑brown dorsally—but the ventral side may appear slightly paler due to the presence of eggs. The abdominal tergites are less tapered, giving a fuller silhouette. In mature females, the ovipositor is evident as a short, pointed extension at the terminal abdomen, often concealed beneath the cuticle but detectable under magnification.
Key distinguishing points:
- Size: females marginally longer and wider than males.
- Abdomen shape: males tapered; females rounded and may bulge when carrying eggs.
- Genitalia: males display a distinct external capsule; females have a concealed ovipositor.
- Ventural coloration: females often lighter, especially when gravid.
Both sexes share the characteristic flat, oval body, six legs adapted for crawling, and wing‑like hemelytra that are reduced to non‑functional pads. Accurate identification requires magnification of the posterior abdomen to observe the sexual structures described above.