From American Cinematographer, Photographing "Days of Heaven" by Nestor Almendros (June 1979)
When the plague of locusts descends on the fields of wheat, Terry's atmosphere of daring and essential simplicity made me suggest a simple technique that would allow us to maintain optimum image quality (without resorting to an optical), and allow us to obtain the maximum dramatic effect.
For our foreground, we used live locusts supplied to us by the Canadian Department of Agriculture, but for the wide panoramics, silhouetted tractors and blackened workers, we used a technique used in The Good Earth: running the camera in reverse and dropping peanut shells from helicopters.
When the film was projected forward the "locusts" would appear to be flying up. Of course, this meant everything had to act or perform in reverse, specifically the actors and the tractors.
Virtually everyone said "No, it will never work." But the few believers convinced them to let us try-- again, special thanks to Terry's daring. And when they saw the rushes, they were astounded.