How can you tell a female bedbug from a male? - briefly
Females have a broader, rounded abdomen that lacks a terminal tip, while males possess a narrower, tapered abdomen ending in a visible genital capsule. This morphological difference is the quickest way to distinguish the sexes.
How can you tell a female bedbug from a male? - in detail
Bedbugs (Cimex lectularius) can be sexed only after they reach the adult stage. The differences are confined to the posterior abdomen and require magnification of at least 30×.
Key external characteristics
- Abdominal shape – Females have a broader, more rounded abdomen that tapers to a pointed ovipositor. Males possess a slimmer abdomen that ends in a slightly concave outline.
- Terminal segment – In females the last abdominal segment bears a visible ovipositor sheath, a small, needle‑like extension used for egg deposition. In males the same region shows the aedeagus, a tubular structure that may appear as a tiny protrusion or a faint groove.
- Size – Adult females are typically 5–6 mm long, while males average 4.5–5 mm. The size gap is modest and should not be the sole criterion.
- Coloration – Both sexes share the same reddish‑brown hue; no reliable color differences exist.
Procedure for accurate determination
- Collect a live adult and immobilize it by placing the specimen in a freezer for 10–15 minutes or by using CO₂.
- Place the bug on a clear slide with a drop of ethanol or water to flatten the abdomen gently.
- Observe under a stereomicroscope focusing on the terminal abdominal segments.
- Identify the ovipositor (female) or the aedeagus (male) based on shape and orientation.
- Record the measurement of overall body length to support the visual assessment.
Additional notes
- Nymphs cannot be sexed because they lack developed genital structures.
- Dissection of the abdomen provides definitive confirmation but is rarely required for routine identification.
- Accurate sexing is essential for studies of population dynamics, reproductive rates, and control strategies.