Re: Are bugs more attracted to white or black light?

Hi Joyce:

The answer to your question is, it depends! As I'm sure you've noticed, lots of insects are attracted to visible light. For instance, moths are often seen circling porch lights- in this case, they actually think the porch light is the moon (for more about that phenomenon, check out this answer from the MADSCI archives: Re: Re: Why do moths fly toward the light?). As well, any kind of "colour preference" would be an attraction to visible light, since anything with a colour is reflecting visible light . All kinds of insects have colour preferences, particularly pollinating insects, and their colour preference is usually tuned to the colour of the flowers they pollinate.

Some insects, however (including moths), are attracted to black light as well (the loud zaps you hear from a bug zapper are usually hapless moths drawn in by the black light). It turns out that many flowers also reflect light in the UV end of the spectrum (and "black" light contains light at the violet and ultraviolet end of the spectrum). This is actually a "colour" preference (colour being defined as light with a certain wavelength) too, albiet one that cannot be defined by humans, because we cannot see UV.

If your question is simply how many insects are attracted to white light versus black light, I'm afraid there is no answer. There are millions of insect species, and many million more that haven't even been discovered yet. The light preferences of most of those species are largely unknown.

Hope that helps!
Rob Campbell, MAD Scientist