We usually hear the annual cicada calling by early July, and from then on through the summer.

The shrill buzzing is a warm-weather sound, heard during daylight and intensifying with heat. These annual cicadas are common insects, more often heard than seen because they sing loudly from trees.

Uninformed people might think the high-pitched buzzing is utility wires vibrating on hot days. Annual cicadas are about 1½ inches long, black with green markings and clear wings.

Males produce the cicada sounds; each species has a characteristic song. I have heard several different cicada species while on family summer trips to Illinois and Nebraska. Their sound-producing mechanisms are complex. The sound is made by air drawn into their bodies and passing across membranes stretched over a pair of sound chambers situated one on each side of the abdomen. Whatever the mechanism, I enjoy hearing these sounds of summer.

There are more than 75 species of cicadas in North America. For most, the life cycle is completed in two to five years.

Female cicadas cut slits in young twigs and deposit eggs there, and as the wingless young hatch they drop to the ground, burrow in and stay there for the prescribed number of years as nymphs.

Jim Gilbert has been a naturalist for more than 50 years.