How can you distinguish a female bedbug from a male? - briefly
Females are larger, with a broader, convex abdomen and a visible ovipositor, whereas males possess a narrower, tapered abdomen. After feeding, the female’s abdomen expands markedly, accentuating the size disparity.
How can you distinguish a female bedbug from a male? - in detail
Female and male Cimex lectularius differ primarily in size, abdomen shape, and genital structures. These characteristics become apparent only under magnification (≥40×).
- Size: Females reach 5–7 mm in length, males 4.5–6 mm. The difference is modest; length alone cannot confirm sex.
- Abdomen contour: Females possess a broader, more convex dorsal abdomen that expands after blood meals and during oviposition. Males retain a slimmer, flatter profile.
- Terminal segment: The female’s posterior abdomen ends in a short, blunt ovipositor used for egg laying. The male’s terminal segment is tapered and bears a visible paramere (clasper) that projects laterally.
- Spermalege: On the dorsal surface of the female’s abdomen, a small, pale, raised area (the spermalege) receives the male’s intromittent organ during copulation. Males lack this structure.
- Genitalia visibility: In ventral view, the female exhibits a paired spermatheca within the abdomen, while the male shows a pair of testes and a distinct aedeagus. Observation requires dissection or slide mounting.
Identifying sex in immature instars is impossible; nymphs lack developed reproductive organs. For reliable determination, collect an adult specimen, immobilize it with cold or CO₂, place it on a microscope slide, and examine the dorsal and ventral aspects. Record the presence or absence of the spermalege, ovipositor shape, and abdomen convexity to assign gender accurately.