The effect is the same as if only one were singing, but in stereo. When dozens or hundreds of katydids chorus, each alternates with his closest neighbor. Such synchronous groups produce a pulsing wave of sound in still night air. The large areas of strutless membrane on their wings vibrate, amplifying the sound produced when the minute ridges of the file rub across the scraper. After a pair mates, the female lays flat, disk-like eggs on her preferred tree or shrub.
Katydids die after mating and laying eggs, their purpose fulfilled.
The following spring, nymphs hatch from the eggs to begin the cycle again, munching leaves and growing until in late summer, they turn to song and sex. The male katydid that I found was quite dead, its delicate, pale green wings and long, bent legs stiff and dry, its protruding shoe-button brown eyes sightless. I hope that its descendants swell the night air with their serenades next summer.