How can you distinguish a female bedbug? - briefly
Female Cimex lectularius are larger than males, exhibit a broader, rounded abdomen, and display a swollen spermatheca near the rear. Their terminal abdominal segment is blunt rather than tapered, providing a clear visual distinction.
How can you distinguish a female bedbug? - in detail
Female bed bugs can be recognized by a combination of morphological traits that differ from males and immature stages. The most reliable characteristics are found in the abdomen, antennae, and genital structures.
The abdomen of a mature female is noticeably broader and more rounded than that of a male, which tends to be slender and tapered. This expansion accommodates the developing eggs and becomes especially pronounced after a blood meal. The dorsal surface of the female’s abdomen often displays a lighter, almost translucent coloration compared to the darker hue of males.
Antennae provide another clear indicator. Female antennae possess a slightly longer third segment, which can be measured against the overall body length. The tip of the third segment may also appear less tapered than in males.
Genital morphology is definitive but requires close examination. Females exhibit an ovipositor—a small, pointed organ located at the posterior end of the abdomen. Under magnification, the ovipositor appears as a pair of elongated, sclerotized structures that are absent in males. Males, by contrast, have a visible aedeagus and a distinct paramere when viewed from the ventral side.
When a specimen is observed without magnification, additional clues can assist identification:
- Egg‑carrying status: Females often retain a cluster of eggs within the abdominal cavity, visible as a faint, opaque mass through the cuticle.
- Behavior after feeding: Females commonly remain near the host longer to digest blood and develop eggs, while males tend to disperse sooner.
- Size range: Adults measure 4.5–5.5 mm; females are generally at the upper end of this range.
For precise determination, a stereomicroscope set to 40–100× magnification should be used to inspect the abdominal tip for the ovipositor and to compare antennal segment proportions. These morphological markers together provide a conclusive method for distinguishing female bed bugs from males and nymphs.