Mystery Cicada Swarms Emerge Across DC, Northern Virginia In 2017

WASHINGTON, DC — A deafening and somewhat nasty phenomenon that longtime Marylanders will recognize has popped up this spring. Cicadas, sometimes known as "17-year locusts," have emerged in big numbers in Washington, D.C., and northern Virginia, as well as the Maryland cities of Columbia, Bowie, Annapolis, Rockville and College Park, says one expert.

The bugs, which, in large numbers can do serious damage to young trees, shrubs and various crops, are always around. But huge broods of them occasionally hatch all at once, usually in 13-year and 17-year cycles. For reasons that scientists are still trying to determine, a brood of cicadas will hatch in off years, which is the case for DC, Virginia and Maryland.

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According to The Gardener's Network, a 17-year brood known as Brood VI hatched last month in Georgia, North Carolina and South Carolina. But Michael Raupp, a University of Maryland entomologist known as The Bug Guy, writes on his latest blog that what experts call "periodical" cicadas may be part of Brood VI, which hatched in 2004 in Maryland, or they could also be an early wave of Brood X, which is due to hatch in 2021.

Theories on the mysterious appearance of the bugs clinging to trees and leaving exoskeleton shells everywhere includes a link to climate change, Raupp said. The numbers of cicadas out in the DC metro area is expected to increase as temperatures rise close to 90 degrees this week.

“We don’t know exactly why this happens. All we know is that it does happen,” Raupp told WTOP.

With temperatures climbing this week, "the entire DMV region should be rocking with these teenagers by next weekend," Raupp says. "So, grab a flashlight and look for a cicada jail break at night, and by day watch the antics of these amazing creatures as the big boy band cranks up in the treetops."

Cicadas emerge from the ground, climb onto trees to mate and then die while their offspring heads back into the soil to emerge in 17 years. Experts say cicadas usually spend six to eight weeks above ground, although their loud "singing" typically lasts for three to four weeks, WUSA reports.

The early visit by Brood X is known as acceleration, he says, when a portion of a cicada brood emerges years in advance of the "billions of cicadas comprising the bulk of their ginormous synchronous brood," Raupp writes.

In 2016, periodical cicadas in some areas hit densities of 1.5 million insects per acre, according to the Washington Post. Fortunately, the adult life span of a cicada is short. The young nymphs often land on trees to shed their skin and become adults. After that, they spend only about four to six weeks above ground before dying.

Contrary to popular belief, adult cicadas do not eat the vegetation that comes into their path. Rather, adult females cut slits into twigs and small branches to lay their eggs. The eggs hatch, creating tiny nymphs, which fall to the ground and burrow, feeding on underground tree roots for years until it's their time to emerge.

Fruit trees are particularly vulnerable to damage by cicadas, along with ash, beech, dogwood, hickory, oak and willow, among others.

Pines and firs, along with most flowers and vegetables, are generally not bothered by the bugs. They also do not bite or sting humans or other animals.

The best defense against cicadas, according to The Gardener's Network, is 1/4-inch mesh netting spread all the way around the tree or plant you want to protect. Insecticides are useless against cicadas.

Anyone who sees periodical cicada nymphs, shed skins or adults on vegetation or on trees is asked to report your sightings to magicicada.org. Cicada experts are attempting to map the distribution of the insects.

Photo via Pixabay; video from Bug of the Week YouTube channel