I was sweeping the first shower of tawny yellow mulberry leaves from our patio when I spotted a pale green grasshopper-like insect among the leaves. It sported long, narrow wings shaped and colored just like leaves, complete with large veins branching into a netlike pattern of smaller veins.

Its leaf green color, those unusual wings, its elongated, slender back legs doubled under like a cricket, and its body-length, fine-as-hairs antennae were all clues to the insect's identity: a katydid.

Katydids are closely related to grasshoppers and crickets, but belong to their own family, Tettigoniidae (Tet-ee-gohn-ee-id-ee), Greek for "small singing insect." Their common name captures the sound of their clicking mating calls: ka-ty-DID or ka-ty-did-NOT. On warm late summer and early fall nights, katydids' dry songs sound as often as 60 times a minute or up to 50 million times in a season.

Large choruses of katydids achieve a striking synchronicity. When two katydids sing together, they alternate, calling and replying, but at half-speed. 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.

Only male katydids are the musicians; their serenades attract amorous females. Like male crickets and grasshoppers, male katyd

ids sing by raising their front wings above their back and rubbing a file-like vein on the underside of one wing over a "scraper," or hardened portion of the wing margin on the other wing. 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.

Although grasshoppers and crickets are "right-winged" (that is, they rub the file under the right wing over the scraper on the left), katydids are left-winged, singing with the left wing overlapping the right.

Katydid females "hear" the males serenade with their elbows. Both males and females possess tympana, or hearing disks, on the "elbow" joint of their front legs.

After a pair mates, the female lays flat, disk-like eggs on her preferred tree or shrub. (Unlike grasshoppers, katydids are arboreal. In the Southwest, for instance, one katydid lives only in the oaks of foothills, chaparral and woodlands; another prefers the creosote bush that clothes mile after mile of the Chihuahuan Desert.)

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.