What scent do bedbugs emit when they are crushed? - briefly
Crushed bedbugs release a faint, sweet‑musty odor that is often compared to coriander or overripe fruit.
What scent do bedbugs emit when they are crushed? - in detail
When a bed bug is crushed, the released fluid emits a distinctive odor that most observers describe as a sweet, slightly musty scent reminiscent of almonds or stale fruit. The smell originates from a mixture of volatile organic compounds (VOCs) present in the insect’s hemolymph and defensive secretions.
Key components identified in analytical studies include:
- Trans‑2‑hexenal – a green, leaf‑like aldehyde that contributes to the sharp edge of the aroma.
- (E)‑2‑hexenal – another aldehyde with a fresh, slightly fruity character.
- 4‑oxo‑2‑hexenal – an oxidized aldehyde adding a faintly bitter note.
- Hexanal and heptanal – aliphatic aldehydes that reinforce the overall musty quality.
- Phenolic compounds – present in trace amounts, they lend a subtle, earthy undertone.
These compounds are released simultaneously when the exoskeleton ruptures, allowing the hemolymph to contact the air. The blend creates a scent that is easily recognizable to humans and can serve as an indicator of infestation during inspection.
In living bugs, a related but separate odor is produced as an alarm pheromone when they are threatened. This pheromone contains similar aldehydes but at lower concentrations, and its purpose is to alert nearby conspecifics rather than to generate a strong olfactory cue for humans.
Laboratory analyses using gas chromatography–mass spectrometry (GC‑MS) have consistently detected the above aldehydes in crushed specimens, confirming that the characteristic smell is chemically derived rather than a by‑product of decomposition. The intensity of the odor correlates with the amount of hemolymph released; a single crushed adult can produce a perceptible scent for several minutes before the volatiles dissipate.