Every 13 years, a big event happens: the mass emergence of the longest-living insect in the United States – the periodical cicada. They last appeared in South Carolina in 2011. Unlike the annual cicadas, which emerge in mid-summer every year, periodical cicadas spend many years as nymphs living in the soil feeding on the roots of trees, which does not seem to cause any tree health issues. Obvious damage to trees is done by the female as she deposits eggs into twigs, which eventually causes a symptom called flagging. This can be alarming but not a real concern for the long-term health of the tree.
In South Carolina, the emergence is projected to be in many upstate counties and counties along the Savannah River basin down to Aiken County. Credit: gisgeography.com/south-carolina-county-map/
The 13-year cicada brood XIX is what is prominent in the South. Emergence in this area usually happens late April into May. Over a period of a week or two, the nymphs crawl out of the ground and up the trunks of trees or other vertical surfaces. They molt one last time to emerge as a winged adult from their nymphal “skin” or exoskeleton. You will commonly see the cast skins attached to tree trunks. Cicadas are harmless to people despite their large size. They are very clumsy fliers and may fly into you, but they are not trying to attack you in any way.
About a week after emergence, they begin flying around to find their mate. Male cicadas sing to attract females for mating purposes, and their sheer numbers can make a deafening noise. There can be as many as 1.5 million cicadas emerging per acre – as much as 30,000 to 40,000 emerging from under a single large oak tree. The adults live only for a few weeks, and after about a month, they will have disappeared as mysteriously as their arrival.
All the periodic cicadas don’t emerge in the same year. There are 15 present-day broods in the United States. Eleven of these broods have the 17-year cycle, and four have the 13-year cycle. Broods are identified by Roman numerals. Brood XIX is one of the largest broods in the country, covering the greatest geographic area. In South Carolina, the emergence is projected to be in many upstate counties and counties along the Savannah River basin down to Aiken County. For more information, see www.cicadamania.com
Map Source: gisgeography.com/south-carolina-county-map/
Emergence holes under an oak tree. Paul Thompson, ©2011, Clemson Extension
