17-Year Cicadas Set to Emerge This Year in Virginia, West Virginia, & North Carolina

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Photo: 17-Year Cicada, courtesy of Joel Mills
Photo: 17-Year Cicada, courtesy of Joel Mills

Many residents in Virginia, West Virginia and a handful of communities in North Carolina should prepare themselves for what may amount to hundreds of millions of cicadas this year.  Scientists say Brood IX of the 17-year periodical cicadas of eastern North America are set to emerge from the earth this spring.

Though there are annual cicadas which emerge every year, it is important for Appalachian residents to note that in addition to the annual cicadas, there are at least 23 different broods in the United States, whose life cycles have them emerging either every 13 years or every 17 years all at once; from time to time these broods can even overlap and even share territory.

This year is Southwest Virginia and Southern West Virginia’s top broods’ turn, with outlier hatchings taking place as far south as North Carolina.

The complicated life cycle of cicadas is one of mystery, fascination and intrigue:

Nearly all cicadas spend years underground as juveniles, before emerging above ground for a short adult stage of several weeks to a few months. They emerge as adults all at once in the same year. This periodicity is especially remarkable because their lifecycles are so long—13 or 17 years.

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The nymphs of the periodical cicadas live underground, usually within 2 ft. of the surface, feeding on the juices of plant roots. While underground, the nymphs move deeper below ground, feeding on larger roots.

The nymphs emerge on a spring evening when the soil temperature at about 8 inches in depth is above 64°. In most years in the United States, this works out to late April or early May in the far south, and late May to early June in the far north. Emerging nymphs climb to a suitable place on the nearby vegetation to complete their transformation into adults. They molt one last time and then spend about six days in the trees waiting for their exoskeletons to harden completely. Just after this final molt, the teneral adults are white, but darken within an hour.
Adult periodical cicadas live only for a few weeks; by mid-July, all have disappeared. Their short adult lives have one purpose: reproduction. The males “sing” a species-specific mating song; like other cicadas, they produce loud sounds using their tymbals. Singing males of a single Magicicada species form aggregations (choruses) that are sexually attractive to females. Males in these choruses alternate bouts of singing with short flights from tree to tree in search of receptive females. Most matings occur in “chorus” trees.

Receptive females respond to the calls of conspecific males with timed wing-flicks, which attract the males for mating.

The sounds of a “chorus”—a group of males—can be deafening and reach 100 dB. In addition to their “calling” or “congregating” song, males produce a distinctive courtship song when approaching an individual female.

Both males and females can mate multiple times, although most females seem to mate just once. After mating, the female cuts V-shaped slits in the bark of young twigs and lays about 20 eggs in each, for a total of 600 or more eggs. After about six to 10 weeks, the eggs hatch and the newborn nymphs drop to the ground, where they burrow and begin another 17-year cycle.

According to scientists at Virginia Tech, cicadas are not poisonous and do not have a stinger. Communities and farms with large numbers of cicadas emerging from the ground often are beset with a substantial noise problem. Half of the population are males “singing” or calling for the females. The annoyance from the singing is tempered by the fact that the periodical cicadas are only out for 4-6 weeks once every 17 years, but they can occur more frequently where broods overlap.  Non-woody plants sometimes will have cicadas resting on the foliage but rarely receive damage.

Agricultural officials also stated, “Adults start appearing in Virginia in early May with numbers peaking in early June. Numbers decline by late June and most cicadas are gone by July. Periodical cicadas emerge in specific locations once every 17 years in most of Virginia. In some of the southern counties there are periodical cicadas that emerge once every 13 years. Most years periodical cicadas will emerge somewhere in the state. Some counties have several broods in different locations. Massive brood emergence is believed to overwhelm predators, which are mostly birds.”

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