Human civilization brings light into the darkness, mostly for a matter of public safety. However, artificial lighting can interfere with natural insect behavior that depends on darkness. A group of scientists surveyed* Photinus fireflires before and after the installation of multiple metal vapor lights. They found that the artificial light reduced firefly occurrence in the lighted area.
Light pollution can have detrimental effects on wildlife. Often, lighting is installed with no concern for the impact it might have on the environment. Studies like this are important for documenting the impact and for providing methods to study light pollution.
*Oskar Hagen, Raphael Machado Santos, Marcelo Nivert Schlindwein, Vadim Ravara Viviani. Artificial Night Lighting Reduces Firefly. 2015. Occurrence in Sorocaba, Brazil.
Advances in Entomology. Vol.3 No.1, Paper ID 53614