The Cicadas Are Nearly Upon Us

Editor’s note: The following story was written by Jim Davis with the Rockbridge Area Master Gardener Association.

As spring turns to summer in the coming weeks, local residents can expect the return of that loud buzzing so familiar in southwest Virginia in warm weather: the song of the cicada.

This year, for reasons not entirely clear to biologists, these insects are expected to appear in greater numbers than usual, making their presence hard to ignore. Think of that buzzing noise as a love song, for it is the male cicada, using a tiny drumlike part of his body, communicating to a female his readiness to mate. In fact, the Latin word cicada is thought to be a coinage suggested by the insects’ sound.

Cicadas have been a part of our planet’s biota for millions of years. Fossil records reveal that cicadas flew among the dinosaurs, well be fore humans shared their territory. They are often encountered in ancient literature and art: Readers of Homer will remember them in “The Iliad.” Aristotle described them in his “History of Animals” and the Roman Pliny included them in his “Natural History.” Most writers agree that this age-old fascination with cicadas is owing to their very distinctive if not unique life cycle.

When the male’s mating song produces the desired outcome, the female deposits her eggs in a tree, making a slit in the bark of a twig. The eggs hatch in a month or two, and the hatchling nymphs fall to the ground and immediately burrow into the soil, forming small chambers for themselves and feeding on sap from surrounding tree roots. Depending on the species, this nymph-stage cicada can last from a few months to as long as 17 years.

Based on the length of this maturation process, all cicada species are roughly divided into two groups: the annual and the periodical. Annual species emerge from the ground after two to five years, and emerge individually, while periodic species remain buried either from 13 or 17 years and emerge as a group, within a short time of each other, as if in response to some mysterious signal.

Once the now-mature cicadas come out of the ground, probably in response to the rise in soil temperature, they attach themselves to trees, using the rough bark to shed their old nymph skins. Most species live for about a month, barring accidents or predators; the purpose is to mate and reproduce, not long-term survival.

Cicadas are not predators. Because they eat only sap, they are seldom harmful to crops. They have no mouth parts to bite or chew, and they do not sting or secrete poisonous or irritating substances. They do seem to collect in annoying swarms and can be a distraction to motorists.

Unfortunately, cicadas get a bad rap because of their mistaken identity. Cicadas are not “locusts.” We have been confusing cicadas and locusts since at least the 17th century, but locusts belong to the grasshopper family and eat almost anything green; cicadas do not. Locusts, under certain, environmental pressures, will swarm in huge numbers and collectively devastate vast areas of vegetation, including croplands; in comparison, cicadas are quite benign.

The more than 3,300 known cicada species across the world range in size from 3/4 inch to as much as 4 inches long, with an amazing variety of colors from pale and drab to brilliant and flashy. They live in every temperate or tropical region on earth; there are at least 190 species in North America and more than 20 in Virginia.

The best known and most studied cicadas in the United State include three with 13-year cycles and three with 17-year cycles. Scientists track them by colonies or “broods” which correspond with the year in which they will emerge. This year, local biologists are following with “Brood IX” in western Virginia, West Virginia, and northwest North Carolina, and expect larger than normal numbers between now and mid-June.

Cicadas are not “locusts.” We have been confusing cicadas and locusts since at least the 17th century, but locusts belong to the grasshopper family and eat almost anything green; cicadas do not.

The News-Gazette

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