Yes, stink bugs (members of the family Pentatomidae) possess a functional visual system. However, their eyesight differs significantly from human vision and is not the primary sense they use to navigate. While they can detect movement and locate general areas of interest, stink bugs rely far more heavily on other sophisticated senses for finding food, mates, and shelter.
The Mechanics of Stink Bug Vision
The primary visual organs of a stink bug are a pair of prominent compound eyes positioned on the sides of the head. These multifaceted structures are composed of numerous individual light-sensing units called ommatidia. Each ommatidium functions as a tiny, separate eye, capturing a small piece of the surrounding environment.
This structure creates a wide, panoramic field of view, effective for detecting sudden changes in light or rapid movement. The trade-off is lower visual resolution, meaning the world appears less sharp and detailed compared to human vision. In addition to the compound eyes, stink bugs possess two small simple eyes, known as ocelli, located on the top of their head. These ocelli do not form images but sense light intensity, helping the insect determine the time of day and orientation during flight.
What Stink Bugs Actually See
The visual perception of a stink bug is tuned to specific wavelengths of light necessary for its survival. Research, such as that on the brown marmorated stink bug, indicates their eyes contain only two types of photoreceptors, suggesting they possess dichromatic vision. These photoreceptors are most sensitive to the ultraviolet (UV) light range (peaking around 367 nanometers) and the green light range (peaking near 519 nanometers).
This spectral sensitivity allows them to perceive UV light (invisible to humans) and green light. Seeing green light helps them locate host plants, their primary food source, while UV sensitivity aids in navigation and detecting light sources. Stink bugs are insensitive to the red end of the visible light spectrum; colors like deep red appear dim or indistinguishable from darkness. Their visual system is optimized for detecting motion over fine detail, making low-resolution movement an immediate signal for a potential predator or mate.
Non-Visual Senses
While sight is functional, the stink bug’s ability to find food and communicate is predominantly governed by non-visual senses. The antennae serve as crucial sensory tools, equipped with microscopic structures called sensilla that facilitate chemoreception (smell and taste). These antennae allow the stink bug to detect the complex chemical profiles of host plants, leading them directly to suitable feeding sites.
Communication over long distances, particularly for mating, relies almost entirely on chemical signals called pheromones. Males release species-specific pheromones that attract females, overriding the need for a visual search. Once close, stink bugs switch to using plant-borne vibratory signals, tapping or vibrating the plant substrate to communicate. This low-frequency mechanical signaling is detected through specialized organs in their legs. Close-range communication is a multimodal exchange involving chemical and vibrational cues.