Why do bed bugs bite in the light? - briefly
Bed bugs normally feed in darkness, but when illuminated they still bite because the host’s skin is detectable and they must complete a blood meal before seeking shelter. Light induces a stress response that shortens feeding time, prompting a rapid bite.
Why do bed bugs bite in the light? - in detail
Bed bugs are attracted to the warmth and carbon‑dioxide emitted by a sleeping host, not to visual cues. However, exposure to light can influence their feeding behavior in several measurable ways.
When illumination is present, the host’s skin temperature often rises slightly due to increased blood flow. This thermal shift creates a stronger gradient that bed bugs can detect with their thermoreceptors, prompting them to move toward the exposed area. In addition, light can cause the host to shift position or uncover previously hidden skin, providing the insects with easier access to blood vessels.
Research shows that many bed‑bug species possess photoreceptive cells that respond to sudden changes in brightness. A rapid transition from darkness to light triggers a stress response, releasing neurotransmitters that heighten activity levels. This heightened state increases the likelihood that the insects will emerge from their harborages and begin feeding.
The following factors combine to produce bites under illuminated conditions:
- Thermal enhancement: Light‑induced skin warming intensifies the temperature cue.
- Increased exposure: Host movement or uncovered skin offers a direct feeding site.
- Photostimulation: Sudden light changes activate the insects’ nervous system, raising locomotor activity.
- Circadian modulation: Bed bugs exhibit peak feeding periods shortly after the host awakens; morning light often coincides with this window, reinforcing the pattern.
Laboratory observations confirm that bed bugs exposed to a 500‑lux light source bite more frequently within the first 10 minutes than those kept in complete darkness. The effect diminishes at lower light intensities, indicating a threshold level for photostimulation.
In summary, illumination does not attract bed bugs directly; instead, it modifies host physiology and triggers sensory responses in the insects that together increase the probability of a bite.