Bees are often seen as tireless daytime workers, leading many to wonder about their activities after dark. While most bee species are diurnal, their behavior shifts significantly after sunset, and some specialized bees are active during the night.
Activity Levels After Dark
Most common bee species, such as honey bees and bumblebees, do not forage or fly outside their nests once it gets dark. Their visual systems rely on sunlight and polarized light for navigation, making nighttime flight impractical and potentially dangerous. As dusk approaches, they return to their hives or nesting sites. Bees caught outside after dark find a sheltered spot, like under a leaf or in a flower, and wait until morning.
Within the hive, however, activity continues with a different focus. The nocturnal hours are used for various internal colony maintenance tasks. Bees process collected nectar into honey by fanning their wings to evaporate water, clean the hive, and tend to larvae. Younger bees, with shorter sleep cycles, often perform these housekeeping duties throughout the night. Guard bees also remain vigilant at the hive entrance, protecting against nocturnal predators.
The Nature of Bee Rest
Bees do not “sleep” in the same way humans do, but they exhibit distinct periods of inactivity that serve a similar purpose to rest. This state, sometimes referred to as torpor, involves a significant reduction in metabolic rate and responsiveness to external stimuli. During these resting periods, a bee’s antennae may droop, its legs flex, and its body and wings relax. In some instances, a deeply resting bee may even topple over sideways.
Scientific observations show that bees in a sleep-like state have reduced brain activity and sensory perception, similar to mammals during sleep. Researchers have found that the brain networks of resting bees switch to a synchronized and reduced information processing mode. This rest is crucial for memory consolidation, allowing bees to process and strengthen memories related to navigation and food sources. Sleep-deprived bees exhibit impaired memory and learning abilities, which can negatively impact their foraging efficiency and overall colony productivity.
Bees That Work Through the Night
While most bees are active during the day, approximately 1% of known bee species are either nocturnal or crepuscular, meaning they are active during twilight hours (dawn and dusk). These specialized bees have evolved distinct adaptations to navigate and forage in low-light conditions. Many nocturnal bees, such as certain sweat bees (Megalopta genalis), have larger eyes and ocelli (simple eyes) more sensitive to light than their diurnal counterparts.
Examples include sweat bees in the genus Megalopta, found in Central and South America. These bees forage in dim light and utilize night-blooming flowers, which offer an advantage by reducing competition with daytime pollinators. Squash bees (Peponapis and Xenoglossa genera) are another example, known for their early morning activity, often starting before sunrise to pollinate squash blossoms that open at night. Male squash bees sometimes even spend the night sleeping inside closed squash flowers, ensuring they are present when the females arrive at dawn.