What do male and female household bedbugs look like? - briefly
Both sexes are reddish‑brown, 4–5 mm long, with flat, oval bodies; females are marginally larger and display a noticeably fuller abdomen after a blood meal. Male bedbugs are otherwise indistinguishable in color and shape.
What do male and female household bedbugs look like? - in detail
Male and female domestic bedbugs (Cimex lectularius) share a generally oval, dorsoventrally flattened body measuring 4–5 mm when unfed and expanding to 6–7 mm after a blood meal. The exoskeleton is a matte, reddish‑brown hue in a fed state; unfed individuals appear lighter, ranging from pale tan to creamy white.
Key morphological traits common to both sexes
- Head: small, concealed beneath the pronotum; eyes are simple ocelli.
- Antennae: four-segmented, slender, extending forward.
- Pronotum: shield‑shaped, covering the thorax, with a smooth margin.
- Legs: long, adapted for rapid crawling; tibiae end in tiny claws.
- Abdomen: segmented, expands significantly after feeding; dorsal surface bears a faint median line.
Sexual dimorphism
- Size: females tend to be marginally larger, especially when gravid, with abdomen length up to 7 mm compared to 6 mm in males.
- Abdomen shape: gravid females display a more rounded, bulging abdomen, while males retain a flatter profile.
- Genitalia: visible only under magnification; males possess a conspicuous aedeagus at the posterior tip, whereas females exhibit an ovipositor opening.
- Color intensity: after a meal, females often retain a deeper reddish tone due to larger blood volume.
Developmental considerations
Both sexes progress through five nymphal instars, each resembling the adult but smaller and lacking fully developed reproductive structures. Nymphs are uniformly pale until their first blood meal, after which they acquire the characteristic reddish coloration.
In summary, while males and females are virtually indistinguishable to the naked eye, subtle size differences, abdominal contour, and genital morphology provide reliable criteria for sex identification.