People are often curious about the activities of bees at night. This topic is the subject of scientific investigation. Here, I’ll draw on some of the research (listed at the end of this page) to answer questions such as:
However, you might also be interested in the page Do Bees Sleep?
Below, you'll find a fair amount of detail into this subject, however, in case you don't have time to read the whole of this article, the main points are:
Below is further information to build on the basic facts outlined above - please see the end of this article for published research papers.
'Night' and 'dark' mean different things to different people. Therefore, we should consider what we mean by night time, and whether we mean total darkness, or at least some light.
A creature may be nocturnal in its habits (active at night), crepuscular (active during dusk and dawn – i.e. twilight); or diurnal (active during the day).
Most bees are diurnal, however, there are exceptions, with a small number of bees being crepuscular or nocturnal.
As far as we are aware, nocturnal or crepuscular lifestyle are mainly tropical species.
Interestingly, a number of tropical wasp species have also evolved this lifestyle. Such bees (and wasps) are able to fly and navigate through a dark forest between their nest and target foraging site.
Nocturnal and crepuscular (dusk and dawn) foraging activity in bees has arisen independently in at least four of the seven recognised families of bees, namely in the Colletidae, the Andrenidae, the Halictidae and the Apidae families of bees (Hopkins et al., 2000; Wcislo et al., 2004; Taylor, 2007; Warrant, 2007).
Nocturnal bees include Megalopta atra (Halictidae; Augochlorini), from the Panamanian highlands) and the Indian Carpenter Bee which is capable of flying out and finding its way even on the darkest nights, and even without the aid of moonlight.
Examples of species known to be crepuscular, include
The sweat bee Lasioglossum (Sphecodogastra) texana is primarily diurnal, but has been found to be capable of foraging at night with adequate moonlight (as least half full moon).
However, to quote scientist and researcher, Eric Warrant (see ref 1 below):
Two species of honeybees (Apidae, genus Apis) are diurnal, but – like Lasioglossum (Sphecodogastra) texana mentioned above, are known to be able to fly out if there is adequate moonlight, and these species are
Some of the reasons why some species have evolved the ability to forage at night or in non-daylight hours, are thought to be as follows:
- Pressures from predators and parasites.
bees foraging at night might be less susceptible to attack from parasites and predators, than those active at night.
Competition for limited food sources
There is less competition for food since there are fewer species active at night, competing for nectar from flowers. Bats and moths are the only notable competitors, rather than a vast number of different bee, butterfly, beetle and fly species (and birds).
pattern of local habitat
In tropical regions, and in tropical forests specifically, some flowers only open at night, whilst some produce nectar both during the day and at night time, and in general, they produce a generous amount of nectar and pollen. Therefore, some bees needed to develop the ability to forage at night time in order to take advantage of the food source offered by these flowers. It’s thought that the abundance of nectar and pollen reserves probably drove bees to forage at dimmer light levels, both later into the evening and earlier in the morning, when the nectar reserves of newly opened flowers are still relatively untapped.
- Some of the bees may live in dry environments, and flying during the colder morning and evening hours minimizes their loss of water (Hurd and Linsley, 1970).
Bees have 5 eyes:
flying bees, the limited amount of light available to night-flying bees, has
resulted in the evolution of proportionately larger compound eyes and ocelli. In particular, the three ocelli(which are
sensitive to light) are significantly larger relative to body size in species
that fly in dim light in comparison with the ocelli found on daylight foraging
bees. (Kerfoot, 1967b; Kelber et al., 2006; Warrant et al., 2006).
For example, in the giant nocturnal Indian carpenter bee (Xylocopa tranquebarica) they measure almost a millimetre across, yet the ocelli of the similarly sized diurnal (daylight active) species X. ruficornis are significantly less than half this size.
The compound eyes are also a little larger in nocturnal bees, but the relative difference in comparison with diurnal species is less pronounced.
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