How do bedbugs see us? - briefly
Bedbugs have two simple eyes that sense light intensity and motion but do not produce detailed images. They locate hosts mainly by detecting body heat and carbon‑dioxide emissions.
How do bedbugs see us? - in detail
Bedbugs possess a pair of compound eyes located on the dorsal surface of the head. Each eye consists of numerous ommatidia, the individual photoreceptive units that form a mosaic visual field. The lenses of the ommatidia focus light onto underlying retinular cells, which generate neural signals in response to photon absorption.
The visual apparatus is adapted for low‑light environments. Peak spectral sensitivity lies in the green‑yellow range (approximately 500–600 nm), matching the wavelengths reflected by human skin under typical indoor illumination. Photoreceptors respond rapidly to changes in luminance, allowing detection of movement and contrast rather than fine detail.
Key visual capabilities include:
- Detection of abrupt light intensity shifts, such as those caused by a host entering a dimly lit room.
- Sensitivity to motion silhouettes generated by the outline of a human body.
- Ability to discriminate between static objects and moving targets based on temporal variations in the visual field.
Vision operates in concert with thermoreception and chemoreception. Heat receptors in the antennae and maxillary palps sense the infrared signature of a warm host, while specialized sensilla detect carbon‑dioxide plumes. The integration of these modalities directs the insect toward a potential blood source, with visual cues primarily serving to orient the initial approach.
Limitations of the ocular system are evident. Spatial resolution is low; individual ommatidia provide only coarse angular sampling, preventing recognition of facial features or clothing patterns. The visual range does not exceed a few centimeters in darkness, and reliance on ambient light makes the system ineffective in complete darkness, where other senses dominate host‑seeking behavior.