Bees are most widely known as daytime pollinators, leading many to ask if these insects possess the ability to see in the dark. The straightforward answer is that the vast majority of bee species, including common honeybees and bumblebees, do not have “night vision” and limit their activity to bright daylight hours. However, a small, specialized group of tropical bees has evolved remarkable adaptations that allow them to fly, forage, and navigate under the dim light of the moon and stars. This capability comes from a profound biological redesign of their visual system, fundamentally changing how they gather light.
How Diurnal Bees Rely on Bright Light
The common diurnal bee’s visual system is built for speed and clarity in a bright environment. Their large compound eyes are composed of thousands of individual visual units called ommatidia, each containing a small lens and a light-sensitive structure known as the rhabdom. This design, known as an apposition eye, is optimized to detect motion and distinguish colors, including ultraviolet light, which is used to see nectar guides on flowers.
Each ommatidium functions independently, meaning light must pass directly through its tiny facet and is not pooled from adjacent units. This creates a sharp image with high spatial resolution, but it severely limits the amount of light collected by the eye. Once sunlight fades to the level of dim twilight, the visual signal becomes too weak and noisy for the bee’s brain to process effectively. This low light sensitivity is the main reason why most bees cease all foraging activity well before sunset.
The Eye Adaptations of Night Flying Bees
The few species that have evolved to fly at night, such as the Central American sweat bee Megalopta genalis and certain carpenter bees, possess distinct physical adaptations to overcome light scarcity. Their compound eyes are significantly larger, and the individual ommatidia have been remodeled to capture available photons. For instance, the facets, which act as the primary lenses, can be nearly twice the diameter of those in a diurnal honeybee.
Underneath the larger lenses, the light-sensitive rhabdoms are dramatically wider, sometimes up to four or five times the width of their daytime cousins. This architectural change increases the surface area for light absorption, making the nocturnal eye about 27 times more sensitive than a typical diurnal bee’s eye. This adaptation sacrifices image sharpness and speed, as the wider rhabdoms create a blurrier picture and slow the visual processing time.
Beyond the physical structure, nocturnal bees also employ a neural strategy called spatial summation. This process pools multiple adjacent light signals together in the optic ganglion. This pooling of faint signals further boosts the overall sensitivity, allowing them to navigate with a visual capability that is closer to true night vision.
Navigating in Darkness Using Other Senses
Even with specialized visual adaptations, night-flying bees integrate non-visual sensory information for crucial tasks like locating food and returning to the nest. Olfaction, or their sense of smell, becomes a highly significant cue. They follow the strong scent trails of night-blooming flowers that are often rich in nectar.
Directional awareness is also maintained by using residual light cues in the night sky. While the primary daytime navigational tool of polarized sunlight is unavailable, these bees can use the subtle patterns of polarized moonlight or the silhouettes of tree canopies against the dark sky. Furthermore, non-visual mechanisms like an internal sense of travel distance are used by bees to successfully measure their path and locate their hive entrance even when the environment is extremely dark.