We have seen a heck of a lot of moths in our house this year. In fact, one rather large sized one, came crashing into our living room window last night- we had our lights on, but it was dark outside- so I am guessing they were attracted to our lights.
Why are moths attracted to light?
The definitive answer to this question remains unknown. There are, however, many plausible explanations for this behaviour. Some scientists, or to be specific lepidopterists (people specialising in the study of moths/ butterflies) believe it could be to do with orientation. In the dark night sky, moths – in particular migratory moths, like the Diamondback moth [Plutella xylostella] – may rely on the light from the moon to help with orientation and they may therefore be attracted to an artificial light (or camp fire even) for this reason.
It is also possible that moths may associate light with the means of an escape from possible danger. The example I came across, explained this reasoning as such: If you were to disturb a bush inhabited with moths at night time, all the moths would fly upwards into the night sky, which, in comparison to the darkness of the ground, would appear to them to be much lighter (and safer).
Are moths attracted to a particular type of light?
Moths are attracted to different wavelengths of light. Every colour of light has a different wavelength and moths respond to some more than others. For example, moths are more sensitive to white light and ultraviolet than yellow light.
Yellow bulbs are readily available to buy and are often advertised as bug lights because it is recognised that moths (and other flying insects) do not respond to them in the same way as white light.
However, before you replace all your light bulbs in your home with yellow ones, I would suggest you read up on how powerful these lights are for everyday use!
What is phototaxis?
Whilst researching the moth’s response to light, I came across a great new word: phototaxis. Phototaxis is the ability of organisms to automatically move in response to the presence of light. As such, moths are positively phototaxic (as they are attracted towards the light) and cockroaches are negatively phototaxic as they hurriedly seek out dark corners and crevices at any sign of light.
I think perhaps the next time I encounter a moth inside my home, I may feel a bit more sympathetic to its plight. Truth be told, the moth is probably the one pest I really do not worry about having in my home. They seem rather harmless, have never done any damage to my clothes or soft furnishings, and they are (in some ways) rather pretty to look at. But am I being too complacent??