Bees are often seen as symbols of sunny days and blooming flowers. This common perception naturally leads to questions about their activity once the sun sets. While many people assume all bees retreat to their hives at night, the reality of bee behavior after dark is more nuanced than it might appear.
Why Most Bees Don’t Fly at Night
Most bee species are diurnal. Their reliance on daylight stems from their visual systems and energetic requirements. Bees navigate primarily using the sun as a compass, even detecting patterns of polarized light in the sky when the sun is obscured by clouds. This navigation system becomes largely ineffective in darkness.
Bees possess five eyes: two large compound eyes and three smaller simple eyes, called ocelli, which detect light intensity and aid in orientation. For most bees, their compound eyes are not optimized for low-light, limiting their ability to discern shapes and landmarks after dusk. Cooler night temperatures increase the energetic demands of flight, as bees must expend more energy to maintain their body temperature for muscle function. These factors make night flight inefficient and dangerous for most bee species.
Bees of the Night
While most bees are daytime creatures, about 1% of species exhibit crepuscular or nocturnal activity. Crepuscular bees are active during twilight hours, at dawn or dusk, while truly nocturnal bees forage in complete darkness. These exceptions have evolved specific adaptations to thrive in low-light environments.
One notable adaptation is found in their visual systems. Nocturnal and crepuscular bees typically have significantly larger ocelli and compound eyes compared to their diurnal counterparts. These enlarged eyes, with increased light sensitivity and specialized neural mechanisms, allow them to gather more photons and process limited spatial information effectively in dim light. Some species, like certain sweat bees in the genus Megalopta, can even fly in rainforest understories at night, with their compound eyes being almost 30 times more sensitive to light than those of worker honeybees.
Beyond visual adaptations, these night-active bees often rely heavily on strong floral scents to locate flowers, as many night-blooming plants emit powerful perfumes to attract pollinators. Examples of nocturnal bees include certain sweat bees (Lasioglossum species) and some stingless bees (Meliponini tribe) in tropical regions. The Asian giant honey bee (Apis dorsata) and a type of African honey bee (Apis mellifera adansonii) can also forage at night given sufficient moonlight.
Risks of Night Flight for Bees
Night flight presents several risks, even for bees adapted to nocturnal activity and especially for diurnal ones caught out after dark. One danger is increased vulnerability to nocturnal predators. Unlike daytime, when avian predators are prevalent, night brings threats such as bats or other nocturnal insects.
Disorientation is another risk. Without the sun’s cues or sufficient light, bees can easily lose their way, making it difficult to return to their hive or nest. This can lead to bees being stranded outside, exposed to the elements. Colder night temperatures also pose a challenge. While some bees can regulate their body temperature, prolonged flight in cold conditions increases metabolic expenditure, leading to exhaustion or hypothermia if they cannot find shelter. A night spent outside the hive without the colony’s warmth and protection can be fatal, particularly as temperatures drop.