That humming, buzzing chorus of insects heard on summer nights is usually due to cicadas -- small, stout-bodied, large-headed insects with sucking mouth parts. Cicadas are usually green with red and black markings. They are an inch or more in length and have 2 pair of wings. Cicadas also have a 3-jointed beak, an abdomen of six segments, prominent compound eyes, and three eyes (ocelli).
Mojave, Great Basin, Chihuahuan and Sonoran deserts throughout the southwest.
Desert, grasslands and woodlands up to 5,000 feet.
Cicadas are of the Family Cicadidae, Order Homoptera. They represent the genera Magicicada and Tibicen. About 1,500 species of cicadas are known, usually occupying deserts, grasslands and forests. More than 100 species are found in North. The Dog-Day Cicada (Tibicen) appears yearly in midsummer, but there are also periodic cicadas. The most common of these is the black and green Harvest Fly, which matures in two years.
The best-known of these is the 17-Year Cicada (Magicicada), which lives only in the United States. After 17 years of dormancy underground, this species emerges for 5 weeks of activity in the sunlight, and then dies. With the exception of the termite queen, this cicada is probably the longest living insect. The 17-year Cicada is often incorrectly called the 17-year Locust. True locusts are grasshoppers.
From June through September, adult males sit in treetops throughout much of North America producing rhythmic ticks, buzzes or whines to attract females. These "songs" result from the vibration of their drum-like abdominal membranes (timbals).
Different species of cicadas can be recognized by differences in their songs, behavior and morphology. Males of each species make three distinct types of sound -- courtship, disturbance and congregational, which varies according to daily weather fluctuations.
After mating, females deposit eggs in slits they cut into twigs and branches. One female lays from 200 to 600 eggs and such activity can sometimes injure ornamentals. Eggs hatch into nymphs, which drop to the ground and burrow into the soil as much as 6 feet. Here they suck juices from roots of perennial trees and shrubs. Depending upon the species, cicada nymphs remain underground from 1 to 17 years.
Then by instinct they leave their burrows to climb the trunk of a tree. Their skins split open, and mature cicadas emerge. Emergence almost always occurs on the same night, although the eggs were laid over a period of weeks years earlier. With the cicada's song, the cycle begins anew.
The loud noise of the male's chorus may repel birds, the cicada's chief predators, but it probably attracts their other primary predator, the King Hornet or "cicada killer" -- a wasp second in size only to the great Pepsis wasp. These wasps sting adult male cicadas, then carry the paralyzed bodies to their burrows upon which the female deposits an egg. The wasp grub hatches and consumes the cicada prior to entering the its own larval stage.
Cicadas don't fly when their body temperature is below 72° F, but maintain full motor control up to 116° F. On very hot desert days, they congregate on the shaded sides of plants and rocks. Their preference for the desert heat provides them an advantage, since most predators don't hunt at midday.
More pictures and information on the Cicadas.