How can I determine whether a bedbug is male or female? - briefly
Examine the insect’s abdomen with a magnifier: females display a noticeably enlarged, rounded abdomen from developing eggs, whereas males have a slimmer, tapered shape. The presence of an ovipositor or visible egg clusters confirms a female.
How can I determine whether a bedbug is male or female? - in detail
Bedbugs exhibit subtle sexual dimorphism that can be observed under magnification. The most reliable method involves examining the terminal abdominal segments, where males and females possess distinct structures.
- Genital plate (paramere) in males: A small, hardened sclerite located on the ventral side of the last abdominal segment. It appears as a pointed or hook‑shaped projection when viewed from the underside.
- Spermatheca in females: A swollen, translucent sac situated near the same segment. It often looks like a tiny balloon or pouch and may contain visible sperm cells if the female has mated.
- Body size: Females tend to be slightly larger and more robust, especially after a blood meal, but size alone is insufficient for accurate identification.
- Abdominal shape: The female’s abdomen is broader and less tapered toward the rear, whereas the male’s terminus is narrower and more pointed.
To perform the examination:
- Collect a live specimen and immobilize it on a cold surface or by carbon dioxide exposure.
- Place the insect under a stereomicroscope at 30–40× magnification.
- Orient the bug ventrally and locate the terminal abdominal segment.
- Identify the presence of a paramere (male) or a spermatheca (female). Use a fine probe if necessary to confirm the structure’s shape.
Molecular techniques, such as PCR amplification of sex‑linked genes, provide definitive results but require laboratory equipment and are rarely needed for routine pest management. Visual inspection of genital morphology remains the standard field approach for sex determination in Cimex lectularius.