Bees are commonly observed during daylight hours, flitting among flowers. Many wonder if these insects ever emerge after dark. While the majority of bee species, including familiar honey bees and bumblebees, are diurnal (active during the day), there are exceptions. A small percentage of bees have evolved to thrive in low-light conditions, challenging common perceptions of bee activity. These nocturnal and crepuscular bees demonstrate unique adaptations that allow them to navigate and forage when most of their counterparts are at rest.
Bees That Are Active at Night
Among the approximately 20,000 known bee species globally, only about 250 (roughly 1%) are active in low light or darkness. These include truly nocturnal bees and crepuscular bees, which are active during twilight hours at dawn and dusk. An example of a truly nocturnal bee is the Indian carpenter bee (Xylocopa tranquebarica), which can navigate and forage even in complete darkness.
Other nocturnal bees belong to the Halictidae family, known as sweat bees. The genus Megalopta, including species like Megalopta genalis, are examples of nocturnal sweat bees found in the Neotropics, particularly in Central and South American rainforests. These bees are known to leave their nests to forage in the evening and before dawn. The Lasioglossum genus also includes species adapted for dim-light activity.
How Nocturnal Bees Navigate
Nocturnal bees possess specialized adaptations that enable them to operate effectively in dim light. Their visual systems are enhanced compared to their diurnal relatives. For instance, Megalopta genalis has compound eyes that are larger and up to 27 times more sensitive to light than those of daytime-active species like the European honey bee. This increased sensitivity is due to larger ommatidial facets and wider rhabdom diameters within their eyes.
The three simple eyes, called ocelli, located on top of a bee’s head, are larger in nocturnal bees. These ocelli play a role in light detection and orientation, helping bees navigate in low light. While these optical adaptations improve light capture, nocturnal bees also employ neural strategies, such as spatial summation, to enhance visual reliability in dim conditions. This allows them to process faint visual information, even distinguishing colors in low light.
What Most Bees Do After Dark
Most bee species, including common honey bees and bumblebees, are diurnal and do not fly at night. These bees rely on sunlight for navigation and foraging, making nighttime flight impractical and potentially dangerous. As darkness falls, the activity of these bees shifts from outdoor foraging to internal hive maintenance and rest.
Inside the hive, bees perform various tasks throughout the night. Younger bees, such as nurse bees, have shorter sleep cycles and remain active, tending to essential duties like cleaning the hive, processing nectar into honey, and caring for larvae. Older forager bees typically rest for longer periods, often between five and eight hours a day, to recover from their daytime activities. They may rest in empty honeycomb cells or cling to the hive walls. The colony as a whole maintains a continuous level of activity, ensuring the hive remains healthy and prepared for the next day’s foraging.