Summer is coming and you will surely hear yourself told (or told in turn) of close the door when it is evening and the light is on because “insects enter”. Speaking of which, have you ever wondered why they are attracted to artificial lights? Today we try to clarify.
Since there are millions of insects on our planet and they all have different habits, giving an answer is not easy. So there are many theories. According to some, perhaps moths use the moon for navigation (and the lights in their eyes look like our satellite); for others the insects are trying to escape towards the light or trying to find the darkness.
How do they seek the darkness by going into the light? Exact! This is due to an optical illusion called the Mach effect, since “the edge of a lighted area will appear darker than the rest of the darkness“, says Avalon Owens of Harvard University; even in 1965 a researcher hypothesized that the lights could somehow mimic mating pheromones.
The most recent theory — published just this year on the bioRxiv preprint server that hasn’t yet been peer-reviewed — is that some insects fly towards the light to orient themselves. This is because to them “light means up” and “dark means down”. “It’s hard for them to use gravity to figure out where their body is, because they’re just swimming through the air”, continues Owens, who was not involved in the new research. With artificial lights, therefore, ”the lighted half of the universe is not where you would expect it to be.“
This year’s research explains why bugs stay near lights once they get there, but not why some of them are “stunned” and others are not.