Why do insects gather around light?
Short answer
Flying insects are not necessarily steering straight toward a lamp. Many flying insects appear to keep the skyward side of their bodies toward the brighter direction, which can help them maintain their orientation.
When a nearby artificial light is brighter than the sky, this response can disrupt their flight. They may circle the light or fall, making it look as if they have gathered there because they like the light.
How it works
In a natural night sky, the sky is brighter than the ground. Treating the brighter direction as “up” can help a flying insect keep its body oriented while it moves.
A streetlight or porch light is much closer and comes from a limited direction. Near it, continuing the same response can bend the insect’s flight path into circles around the source and make controlled flight difficult.
Key point
Different species respond differently depending on the light’s color and direction, as well as the surrounding brightness. It is too simple to say that insects always fly to light from far away; artificial light can also confuse the orientation cues they use while flying.