Artificial light attracts insects, so there is a risk of it interfering with the natural habits of nocturnal animals.

Orange and red components less attractive to insects

Light with a predominantly yellow/orange and red spectral content is not so attractive to insects because their eyes have a different spectral sensitivity from the human eye. Insects respond more sensitively to the spectral composition of light from fluorescent lamps and high-pressure mercury vapour lamps. Pale moonlight, which insects are thought to use for orientation, also appears much brighter to the insect eye than to humans.

However, the light emitted by high-pressure sodium vapour lamps appears darker. Orange and red spectral components produce virtually no response. So the use of these lamps reduces interference with nocturnal insect life.

A summary of what science knows about this subject is contained in the LiTG publication "Zur Einwirkung von Aussenbeleuchtungsanlagen auf nachtaktive Insekten" (Impact of exterior lighting systems on nocturnal insects).