Common bees such as Western honey bees and bumblebees are not considered nocturnal, but there are bee species that are. These nocturnal bees forage and work at night or at dusk while other species of bees sleep. The differences in their eyesight allow them to have an advantage over other species when it comes to navigating in dim light.
Which Species of Bees Are Nocturnal?
About 250 bee species are identified as nocturnal. These include crepuscular bees, which are species that are active during dusk or dawn. Although nocturnal is used as an umbrella term for both night bees and crepuscular bees, there are differences between the two identifications.
What Is the Difference Between Nocturnal, Crepuscular, and Diurnal?
Truly nocturnal creatures are out for entire nights at the darkest hours. This is also known as being obligately nocturnal.
The Indian Carpenter bee is the only bee that is truly and obligately nocturnal. The species can forage in complete darkness, while other nocturnal and crepuscular bees need moonlight to navigate.
Crepuscular describes animals that are active during twilight or whenever there is dim light, like at dawn. They’re not capable of foraging or hunting during darkness, but use moonlight to venture out.
There are many crepuscular bee species in tropical or warmer areas of the world. This group makes up the 250 species that identify as nocturnal, but not truly nocturnal.
Creatures that are active in the daytime are diurnal. Their need for light is why they will hide and sleep at night. 99% of bee species are diurnal.
What Do Nocturnal Bees Do at Night?
Nocturnal and crepuscular bees forage and collect pollen just like diurnal bees. Crepuscular worker honeybees bring nectar back to hives while there is dim light or moonlight.
The Indian Carpenter bee, the only true nocturnal bee, collects food and goes back to its individual nests. These bees are solitary and therefore do not have colonies to report to.
How Are Nocturnal Bees Able to Stay Out at Night?
Since nocturnal and crepuscular bees are rare, it’s been difficult for scientists to completely understand what makes these species unique. However, external anatomy gives some insight into nocturnal bees’ separate abilities.
Bees’ eyesights are made up of complex parts that allow them to see polarized light and process images at a quick rate. Their vision is a primary tool in foraging. Nocturnal bees have larger eye parts that help them make use of the little light outside.
How Do Nocturnal Bees’ Eyes Help Them See at Night?
Bees have five eyes. Two are compound eyes and three are ocelli. Compound eyes are the large eyes on the side of bees’ heads. These parts process colour, light, and images. Ocelli are three tiny eyes between the compound eyes. These don’t see colour but are sensitive to light.
Crepuscular and nocturnal bees are found to have larger ocelli. The unusual sizes of nocturnal bees’ ocelli indicate greater sensitivity to light than that of their diurnal cousins. This is how they’re able to see gaps of light in the tropics or moonlight.
Indian Carpenter bees, however, have larger ocelli and compound eyes. Both types of eyes were more sensitive than diurnal and crepuscular bees’. Researchers have determined that these differences in Indian Carpenter bees’ eyes were not significant enough to explain the species’ ability to roam under no light. Bees’ electromagnetic senses may contribute to this species’ nocturnal status.
Nocturnal Bee Species Make Up 1% of All Bees. This decreases the competition to mate or forage in the evenings. These species may have advantages over diurnal bees as they have more access to pollen and nectar.
Where Can Nocturnal Bees Be Found?
There are nocturnal bees in tropical parts of the world, however, there are some species in drier places. The commonality between both types of climates is hot temperature.
All bee species survive in warmer temperatures and are sensitive to the cold. This is another indicator as to why nocturnal species evolved to drop their diurnal rhythms. Nighttime in most places bees are found is cold. The warm weather invites common bees to seek out nectar, and they keep to their hives in the winter.
Nocturnal and crepuscular species are not exempt from their need for warmth. The temperatures of tropical and dry areas stay warm throughout the evenings.
Why Do Some Diurnal Bees Stay Out at Night?
Diurnal bees sleep in their nests or hives at night. This is where it’s warm and safe for them to relax. Nocturnal bees will sleep in the daytime.
Diurnal bees will rarely venture out in the nighttime. Those that do may have been disrupted by artificial lights at nighttime. This is much like how the human circadian rhythm works, where the light at inappropriate times can turn circadian rhythms askew.
Additionally, diurnal bees preyed on by certain parasites will display nocturnal behaviour, on top of other odd changes. The Zombie Fly parasite leads bees to have an increased attraction to light. The bees will come out at night or in adverse weather to seek out sources of light.
How Are Nocturnal Bees Different From Honey bees?
Although there are honey bees that are nocturnal, there are differences between average honey bee species and nocturnal species.
|Circadian Rhythm||Diurnal - Awake in the daytime||Nocturnal or crepuscular - awake at twilight, dawn, or night|
|Eye Size||Average-sized compound eyes and ocelli||Large ocelli and sometimes large compound eyes|
|Body Size||Average||Sometimes larger than average|
|Habitat||Anywhere with four seasons||Hot, arid, or humid|
Most people won’t see nocturnal bees in their lifetimes since they thrive in dim light. Melittologists (those who study bees) continue to research what makes a nocturnal bee species operate differently from diurnal ones.