Bees are commonly observed foraging during daylight, leading many to assume their activity ceases at sunset. While this is true for most species, the reality of their nocturnal habits is more complex. Understanding what bees do after dark reveals a nuanced world of adaptation and intricate colony behavior.
General Bee Activity Patterns
Most bee species, including honey bees and bumblebees, are diurnal, meaning they are active during the day. Their foraging activities rely on sunlight for navigation, using the sun as a compass or polarized light patterns. Their vision is not well-suited for low-light conditions, making it difficult to locate flowers or find their way back to the hive in darkness.
Most flowers providing nectar and pollen are also open during daylight hours. As dusk approaches and light levels diminish, these diurnal bees return to their nests or hives. This return ensures their safety from nocturnal predators and allows them to prepare for the next day’s foraging.
Nocturnal and Crepuscular Bees
While most bees are diurnal, about one percent of species (around 250) are crepuscular (active at dawn and dusk) or nocturnal. This specialized behavior evolved independently in families like Halictidae (sweat bees) and Colletidae. These bees possess adaptations for low-light navigation and foraging.
Many have larger ocelli, simple light-sensitive eyes on their heads, enabling them to gather more light. Their compound eyes also feature more light-sensitive units, or ommatidia, enhancing their vision in dim light. For instance, the Neotropical sweat bee, Megalopta genalis, has eyes significantly more sensitive to light than diurnal bees, allowing it to forage in light intensities dimmer than starlight. These bees often specialize in foraging on flowers that bloom at night, which typically emit strong scents to attract pollinators in the absence of visual cues.
What Bees Do Inside the Hive at Night
For bee species that return to their hives or nests at night, colony activity continues. Honey bees, for example, do not simply rest once inside; they process resources collected during the day. Worker bees convert nectar into honey by fanning their wings to evaporate excess water, reducing moisture from 70-80% to 17-20% for stable honey.
Bees also tend to the brood (eggs, larvae, and pupae), ensuring they are fed and cared for. Cleaning tasks are ongoing, and the colony maintains a consistent hive temperature, often around 33-36°C (93-97°F), even through cooler nights. Young bees remain active, engaging in these internal maintenance tasks.