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.
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.
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)