Sports fans want to know, “Why were there so many moths at Euro 2016?” Insect Biologists point to several factors. Many of the moths were Silver Y moths, Autographa gamma, named for the Y-shaped (or gamma-shaped) marking on the wing. These moths are migrants that fly between Europe and North Africa. Two major migration swarms occur: One in spring and one in Summer. Euro 2016 coincided with the 2016 summer migration. Thus, large swarms of moths were in the area.
Bright lights can attract moths. To enhance security, the stadium lights were turned on the night before and left on all night. The stadium lights form a ring around the outside of the stadium. Bright lights disorient flying insects. Moths entering the stadium ring of lights would have difficulty orientating in a manner that would allow them to exit the stadium. They fly in circles. The lights on policy attracted and trapped moths.
Many moths, including the Silver Y, are inactive during the day. At daylight on game day, moths trapped inside the stadium settled onto the field and into the seats waiting for cover of darkness to resume their migration. Their rest was disturbed by fans entering the stadium and athletes running on the pitch. Thus the spectacle of moths flying around adding a special ambiance to the match.