Ever wonder why our porch lights seem to be the appointed meeting places for all our favorite critter friends? I know I always have and what better opportunity to learn than now. I found this beautiful butterfly outside Crown Hall one night as I was leaving, and it brought this question up again. Are insects just afraid of the dark? Actually, they need light to navigate, and before our artificial lights started going up everywhere, they would rely on the stars and the moon as “fixed light points” to find their way.
This phenomenon of their response to a light source is known as phototaxis. We mislead them by adding more of these “fixed light points” that essentially get them nowhere they really want to be. Moths, especially, get really confused as they perceive the light as being stronger in one eye than the other. As a result, one of their wings will also flutter faster than the other making our poor little friends fly in a circle around the light source!
This helpless butterfly I observed striving in vain to gain entry to the brightly lit aquarium that is Crown Hall struck my attention. He fluttered continuously back and forth against the glass, wondering why exactly he couldn’t reach the bright source of his fascination.