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Brood X — the emergence has begun

Molting 17-year periodical cicada, Magicicada septendecim (Provided photo — Bob Rabaglia, Maryland Department of Agriculture, Bugwood.org)

Brood X is coming. In fact, by many accounts the invasion has already begun. The emergence of Magicicada septendecim, a species of 17-year periodical cicadas, the largest periodical emergence of insects on Earth.

Periodical cicadas are large, fat, dark brown flying insects averaging about 1-and-a-half inches in length with a 3-inch wingspan. Pigmented veins form a noticeable “W” on the outer end of their front wings. Their eyes are bright red.

Different broods of periodical cicadas emerge at different intervals. Some appear annually, some at two- and four-year cycles, others every 13 or every 17 years. According to Jody L. Gangloff-Kaufmann, a Cornell entomologist working in community (non-agricultural) integrated pest management, Brood X (broods are labeled with Roman numerals), sometimes referred to as the Great Eastern Brood, “is one of 15 broods of periodical cicadas that appear regularly throughout the eastern United States.” Each one is distinctly different. Brood X “has the greatest range and concentration of any of the 17-year cicadas.” Their habitat runs nearly the entire length of the East Coast, from Georgia to southern New York (primarily parts of Long Island and New York City — not in the North Country) and as far west as Nebraska and Missouri. When they last appeared, in 2004, parts of the Northeast were inundated with them. They appeared in swarms, literally flying into everything. Vast areas were littered with their remains, and in some locations, the noise was deafening.

That was the year this generation was spawned. They’ve remained underground since, waiting for the coming of the 17th spring, living on sap drawn from the roots of deciduous trees. Apple, maple, oak, ash, cherry and beech are among their preferred hosts. Thousands may live on the roots of just one tree. Yet even in such large numbers, they cause very little or no harm.

When they’re ready to surface and climb, sometime between now and early June, the still-wingless nymphs dig their way out of the soil, appearing suddenly, usually after sunset, in staggering numbers. A million or more per acre is not at all unusual. They crawl into the trees, shed their skins and emerge as adults. The molt takes only hours. And by morning, they’re ready to take to flight.

This female, left, and male periodical cicada are from the 17-year brood, Magicicada septendecim. (Provided photo — Lee Garret, Bugguide.net, Iowa State University Department of Entomology)

Even though billions emerge simultaneously, they do very little damage. Contrary to popular belief, they don’t feed on vegetation. In fact, adult cicadas don’t feed at all. They sing, mate, lay eggs and die. The eggs hatch within six to eight weeks, and the newborn nymphs drop to the ground and immediately work their way into the earth, where they’ll live for the next 17 years.

The greatest damage linked to the emergence of periodical cicadas takes place during egg laying. Each female cicada lays several hundred eggs in the small limbs and twigs of host trees and woody plants, using her oviposotor to cut numerous slits through the bark and into the sapwood. In large trees, this isn’t a problem. But the puncture wounds can damage young trees, especially nursery trees and trees recently transplanted into orchards. The tips may wilt and die, and the wounds may serve as entry points for other insects.

The mass emergence of periodical cicadas represents a feast for birds, frogs, rodents, snakes and other predators that gorge themselves on the insects. (Pets may become gluttonous, too.) A fish feeding frenzy is said to occur in some places. With so much for them to eat, fish stop biting, and catching them becomes nearly impossible.

Cicadas were eaten by Indigenous people in North and South America, Australia, parts of Asia including China, and in jungle regions of the African continent. Evidently the newly emerging nymphs and adults that have just shed their nymphal skins are quite tasty. They can be fried and eaten like popcorn. They’re low in fat, high in protein and offer a desirable balance of vitamins. Some who have eaten them say they taste a bit like shrimp. Any takers?

Several medical applications have been chronicled, too, including their use as a diuretic and as a treatment for earaches and ear infections. In some cultures, the cast skins were brewed into a tea and given to agitated babies to calm them down.

A 17-year periodical cicada, Magicicada septendecim (Provided photo — John Ghent, Bugwood.org)

It’s interesting to note that within certain ancient civilizations, including some Native American communities, their periodic appearance was associated with the coming of evil. The European settlers, having never seen periodic cicadas, mistook them for locusts and feared a plague of biblical proportions. Even today, they’re often mistakenly called locusts, which they are not.

Periodic cicadas are generally considered beneficial in that they prune trees, aerate soil and supply nitrogen to the soil as their remains decompose. They should probably be looked at as quite marvelous, an awesome spectacle to be enjoyed. After all, the next generation of Brood X will not emerge until the year 2038.

If you’d like to learn more about Brood X cicadas, WROC-TV, a CBS-affiliated television station in Rochester, has posted an interesting, to-the-point Q&A with Dr. Gangloff-Kaufmann offering her expertise. That interview can be found here: youtube.com/watch?v=5KhgoOvpw_0.

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