How can you distinguish the female from the male of a bed bug? - briefly
Female bed bugs are larger, with a broader, rounded abdomen that expands after feeding and a visible ovipositor at the rear; males are smaller, have a narrower, tapered abdomen and lack an ovipositor. Under magnification, males display small genital claspers on the terminal segments, which are absent in females.
How can you distinguish the female from the male of a bed bug? - in detail
Bed bugs (Cimex lectularius) can be sexed by examining external morphology under magnification. The adult female is generally larger, measuring 5.0–5.5 mm in length, whereas the male averages 4.5–5.0 mm. Size differences are subtle; reliable identification relies on specific anatomical features.
Key distinguishing characteristics:
- Abdominal shape: The female’s abdomen is broader and more rounded, expanding laterally to accommodate developing eggs. The male’s abdomen remains slender and tapers toward the posterior.
- Genital capsule: In females, the terminal segment bears a visible ovipositor sheath and a smooth, rounded dorsal surface. Males possess a pair of curved parameres and a distinct, pointed genital capsule visible on the ventral side.
- Scent gland openings: Males often exhibit prominent, darkened scent gland openings (pheromone glands) on the ventral thorax, whereas females have less conspicuous glands.
- Coloration: Females may appear slightly lighter due to a more translucent cuticle over the enlarged abdomen; males retain a uniformly darker hue.
Behavioral cues supplement morphological assessment. Females lay eggs in small clusters (5–7 eggs) within crevices, a behavior absent in males. Males are more mobile during mating periods, actively seeking receptive females.
Practical procedure for sex determination:
- Collect live specimens and immobilize them on a cold surface.
- Place individuals under a stereomicroscope at 40–60× magnification.
- Observe abdominal contour and terminal segments for the features listed above.
- Record measurements to confirm size ranges if needed.
Accurate sex identification supports population monitoring, control strategies, and research on reproductive biology.