Why are bedbugs red? - briefly
Bedbugs look reddish because their translucent cuticle reveals the blood they have consumed, giving the insects a pink‑to‑rust coloration. The hue intensifies after a meal as the abdomen expands with digested blood.
Why are bedbugs red? - in detail
Bed bugs (Cimex lectularius) display a reddish hue because of several physiological and biochemical factors that become evident after they have fed. Their exoskeleton is naturally a pale brown, but the ingestion of mammalian blood introduces large quantities of hemoglobin, a red pigment that diffuses through the insect’s body cavity. As the blood is digested, hemoglobin breakdown products, primarily heme and its derivatives, remain in the hemolymph and give the abdomen a conspicuous crimson coloration. This coloration intensifies shortly after a meal and fades gradually as the insect metabolizes the nutrients.
Key contributors to the observed color include:
- Hemoglobin content – the primary source of red pigment after a blood meal.
- Cuticular translucency – the thin, semi‑transparent cuticle allows internal coloration to be visible.
- Digestive enzyme activity – proteases break down hemoglobin, releasing heme that retains its red chromophore.
- Age and feeding frequency – recently fed, younger adults appear brighter red than older, unfed individuals.
The red appearance is not a permanent feature of the species; unfed or starved bed bugs revert to their natural brownish tone as the residual blood is fully metabolized. Moreover, environmental factors such as temperature can affect metabolic rate, influencing how quickly the red coloration diminishes. The combination of blood-derived pigments, cuticle properties, and metabolic processes fully explains the characteristic reddish look of these insects after feeding.