Bees play an indispensable role in ecosystems by pollinating flowering plants. Their daily routines are linked to light and temperature, guiding foraging and internal colony functions. Understanding bee activity offers insights into their survival strategies and community interactions. This article explores typical bee behaviors over a 24-hour cycle, highlighting how most species operate and the exceptions.
The Diurnal Nature of Most Bees
Most bee species are diurnal, meaning their peak activity occurs during daylight. This reliance on daytime is due to navigation methods; many bees, including honeybees, use polarized light in the sky as a compass. They can detect these light patterns even when the sun is obscured, helping them navigate to food sources and back to their hive. Bees are cold-blooded, requiring external warmth from sunlight for flight. Foraging typically begins when ambient temperatures reach at least 12.8°C (55°F).
Floral resource availability also dictates daytime activity. Most flowers open and release nectar and pollen during the day, providing food when light and temperature are favorable. While bees prefer moderate temperatures, they may adjust foraging times during extreme heat, opting for cooler periods in early morning or late afternoon. Very high temperatures, exceeding 35°C (95°F), can reduce their activity, as they struggle to maintain optimal body and hive temperatures.
Nighttime Activities of Bees
Once the sun sets, most diurnal bees cease external activities and return to their nests or hives. Their vision is not well-suited for low-light, making outdoor navigation challenging after dark. Inside the hive, the colony remains active, with continuous internal work.
At night, bees process the day’s collections. Worker bees fan their wings to evaporate excess moisture from nectar, transforming it into honey. They also store pollen, build and repair honeycomb, and feed larvae and the queen. Individual bees rest, often taking short naps (5 to 7 hours total), adopting relaxed postures with drooping antennae and resting wings. Younger bees, involved in hive maintenance, might exhibit less structured sleep patterns than older foraging bees.
The Exception: Bees Active After Dark
While most bees are diurnal, about 1% of described species are active during twilight (crepuscular) or full nighttime. Examples include certain sweat bees, such as Megalopta genalis found in tropical rainforests, and Lasioglossum (Sphecodogastra) texana. The giant honey bee, Apis dorsata, also demonstrates crepuscular and nocturnal foraging, especially during bright moonlight.
These night-active bees have adaptations enabling them to navigate and forage in dim light. They typically have significantly larger apposition compound eyes and larger ocelli, which are simple eyes located on top of their heads. These enlarged visual organs, particularly the ocelli, are more sensitive to light, aiding in their orientation and ability to gather sufficient photons in low illumination. Their visual systems incorporate specialized neural mechanisms that enhance light capture and process visual information, sometimes by integrating signals over space and time.
Beyond visual adaptations, nocturnal bees often rely heavily on strong floral scents to locate their food sources, as many night-blooming flowers emit powerful perfumes rather than relying on visual cues. These flowers release specific aromatic compounds, like 2-phenylethanol and benzyl alcohol, or terpenoids, which guide the bees in the dark. This specialized foraging behavior allows them to exploit a niche with reduced competition from diurnal pollinators and potentially lower predation risks.