Bees perform the bulk of pollination for both wild and cultivated plants. Their visible activity—the buzzing flight from flower to flower—is not constant throughout the year or even throughout a single day. When bees come out depends entirely on the species and a complex set of environmental conditions that trigger their emergence from a dormant state or their departure from the nest. This cycle is governed by seasonal changes, temperature minimums, and daily light levels.
Seasonal Awakening: The Annual Start
Honey bee colonies are perennial and do not truly hibernate. Instead, they form a dense winter cluster within their hive, shivering their flight muscles to maintain warmth. Their first emergence in late winter or early spring is often a “cleansing flight,” an opportunity for the workers to eliminate waste outside the hive on a relatively warm day, signaling the beginning of their active year. The need to expand the colony is synchronized with the increasing minutes of daylight following the winter solstice, initiating the queen’s heavy egg-laying schedule.
Bumble bees and the vast majority of solitary bee species follow a different annual schedule because their colonies are annual. Only the newly mated queen bumble bee or the mature, solitary female overwinters, typically hidden underground or in a protected natural cavity. These overwintering females emerge later than honey bees, usually in mid-spring, to begin foraging, build a new nest, and lay their first batch of eggs.
Solitary bees, such as mason bees, emerge as fully formed adults from the sealed cells their mothers provisioned the previous year. Their appearance is perfectly timed with the blooming of their specific host plants. Regional climate plays a significant role in this timing, with bees in southern latitudes emerging weeks or even months earlier than their northern counterparts, where the risk of late-season frost is higher.
The Temperature Threshold for Flight
Bees are generally active when the ambient air temperature is above 50 to 55 degrees Fahrenheit. Before taking off, a foraging bee must raise its thoracic temperature—the segment containing the flight muscles—to at least 85 degrees Fahrenheit. They achieve this through a process similar to shivering, rapidly vibrating their flight muscles without moving their wings in a controlled burst of thermogenesis.
Bumble bees are particularly adept at this process, allowing them to begin foraging at much cooler ambient temperatures than honey bees. The presence of direct sunlight is another significant factor, as solar radiation can dramatically accelerate the warm-up time for a bee, enabling them to leave the nest earlier in the morning. Bees can sometimes be seen flying on a sunny, windless day even if the air temperature is below the typical flight threshold. However, if the air is too cold, the bee risks losing heat faster than it can generate it, which limits the duration and distance of their foraging trips.
Daily Foraging Schedules
The daily foraging schedule of most bee species is closely tied to the peak availability of nectar and pollen in flowers. Activity generally ramps up in the mid-morning, after the sun has warmed the environment and evaporated any overnight dew that might dilute nectar stores. Maximum foraging usually occurs between 10:00 am and 4:00 pm, representing the period of highest floral resource secretion and optimal flight conditions. Individual bees may make multiple trips during this time, with each foraging flight lasting around 50 minutes on average.
Activity gradually declines in the late afternoon and typically ceases entirely around sunset or shortly before, though this can vary by species. The primary factor governing the end of the day’s activity is the drop in light intensity, which makes navigation and locating the nest entrance difficult. Specialized bees, such as certain squash bees, have evolved to forage exclusively in the very early morning to access flowers that close by mid-day. For the vast majority of diurnal bees, the drop in light and temperature signals a return to the safety of the nest to rest and process the day’s collected resources.