Science Questions

Why do insects buzz around my light?

Mon, 2nd Dec 2013

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Leigh asked:

Why do insects buzz around my light? Moths seem to love my kitchen light in particular!


Ian Burgess is the director of Insect Research and Development Ltd, in Cambridge...

Ian -   The short answer is, nobody White peppered mothknows. 

There are lots of theories and some of those are a bit more logical than others, but most of them are definitely speculative and others are definitely disprovable.

One suggestion is that moths mistake lights for the moon.  The reason for that is because some moths that migrate use the moon to orientate which direction they're travelling. But that doesn’t explain why nonmigrating moths - which is the vast majority of them - and other insects actually get confused by lights because the moon has no impact on them at all.

Others suggests that maybe insects get dazzled. Well, that can't happen at a distance, and a candlelight or a camp fire - or even a spotlight if you're half a mile away - doesn’t look very bright.

Some people speculate that the pheromones that female moths release produces a faint luminescence (glow), and that male moths can detect light in the environment and confuse those with the luminescence from the female pheromones. But that, of course, would only apply to males. What about the females? 

It seems that wavelength of light is important, and it has been noted that the newer white or bluish-white lights now used in street lamps are actually are more attractive to moths than the traditional organge sodium lights, that we’ve had for many years. But, again, it doesn’t explain why insects that have been adapted for millions of years of evolution to fly about happily in the dark - and are quite normally conditioned to hide away from light during the day - should suddenly suicidally rush to all illuminated objects like cars and street lamps that are none of their business...

So, the answer is we really don't know!


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