Nocturnal Bees

Did you know that there are nocturnal bees?  Yes, it’s true! There are bees that fly at night.  Some are crepuscular (they fly in the early dawn and late dusk hours), and some, like this Xylocopa (carpenter bee) species fly only at night.

Nocturnal Xylocopa, source

Nocturnal Xylocopa, source

One thing that distinguishes these nocturnal bees from their diurnal (day flying) counterparts is the size of their ocelli, which are light receptive lenses on the tops of their heads.

The nocturnal Xylocopa next to a congeneric Xylocopa (sonorina)

The nocturnal Xylocopa (left) source next to a congeneric Xylocopa (sonorina) source (right)…the ocelli are relatively larger in the nocturnal species.

It it is thought that the nocturnal bees were independently derived in four different bee families (Andrenidae, Apidae, Colletidae, and Halictidae). There are two hypotheses for why these bees have become nocturnal. 1) To avoid competition with other bees.  Because of the challenges involved with night flying, there are fewer species taking advantage of night flowering plants.  2) To avoid predation and parasitism because most predators and parasites fly during the day! (Warrant 2007)

It is very challenging indeed for these bees to fly at night, and in fact, my favourite line from the Warrant (2007) paper is: “Moreover, it is very likely that nocturnal bees (and indeed many other nocturnal insects) are also able to enhance vision at a higher level in the visual system by neurally summing photons in space and time.” (emphasis mine)


9 thoughts on “Nocturnal Bees

  1. Oh! I want to do that! Summon photons in space and time. Summon them right here, right now! I’m sure that I don’t have that capability and am not likely to get it, but it’s kind of neat that something can do it! I perhaps have been studying the wrong things all my life, from what you have written . . . insects seem to have a lot of truly remarkable capabilities. Perhaps they should be studied more widely and what they know how to do could be the basis for new discoveries leading to new human capacities. Or at the very least, new superhero traits! Think of it! LadyBee, summoning photons through time and space to light up the world’s dark corners!!

    • You’re not daft! I’m sorry, that is my mistake. I presented the sentence out of context. Basically, the particles of light that we use to see are filtered through the light receptors in the eye and then to the brain. In us, there is a visual cortex (I’m not sure how this works in insects!) and the visual cortex uses the light to draw edges and shapes and movement. Instead of all these subtleties, the bees sum all the light from a given spatial area and give a rough idea of whether there is an object there or not. They lose the ability to distinguish details, but can use much less light to travel around at night. Does that make more sense?

      • That does make sense, thank you! I have read that honey bees switch to seeing in black and white when flying at speed, as this takes less effort and is all they need to navigate.

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