American management courses often tell a story about a monument in Washington. Its stone is wearing away from harsh cleaning. The cleaning is needed because of bird droppings. The birds come to eat spiders, the spiders come to eat insects, and the insects are drawn by the lights at dusk. Change the lighting, and the problem is solved.
There was a real study. The insects at the Lincoln and Jefferson Memorials were midges, studied by the entomologist Don Messersmith. In early 1990 a six-week test turned the lights on an hour after sunset three nights a week, and the midges fell by 85 percent. In May 1990 a 50-pound block of marble fell from the memorial.
The lighting change was dropped after photographers complained. By September 1995 it was no longer under consideration. Both memorials were repaired instead, in a program that took more than five years and cost $25 million.