Yesterday, a hike through a peaceful ridgetop woods in the Furnace Hills of southern Lebanon County resulted in an interesting discovery. It was extraordinarily quiet for a mid-April afternoon. Bird life was sparse—just a pair of nesting White-breasted Nuthatches and a drumming Hairy Woodpecker. A few deer scurried down the hillside. There was little else to see or hear. But if one were to have a look below the forest floor, they’d find out where the action is.
Not much action in the deer-browsed understory of this stand of hardwoods.Upon discovery beneath a rock, this invertebrate quickly backed its way down the burrow, promptly seeking shelter in the underground section of the excavation.A closeup of the same image reveals the red eyes of this Periodical Cicada (Magicicada species) nymph. It has reached the end of seventeen years of slowly feeding upon the sap from a tree root to nourish its five instars (stages) of larval development.
2021 is an emergence year for Brood X, the “Great Eastern Brood”—the largest of the 15 surviving broods of Periodical Cicadas. After seventeen years as subterranean larvae, the nymphs are presently positioned just below ground level, and they’re ready to see sunlight. After tunneling upward from the deciduous tree roots from which they fed on small amounts of sap since 2004, they’re awaiting a steady ground temperature of about 64 degrees Fahrenheit before surfacing to climb a tree, shrub, or other object and undergo one last molt into an imago—a flying adult.
Here, approximately one dozen Periodical Cicada nymphs have tunneled into pre-emergence positions beneath a rock. Seventeen-year Periodical Cicadas, sometimes mistakenly called “seventeen-year locusts”, are the longest-lived of our insects.Note the wings and red eyes beneath the exoskeleton of this Periodical Cicada nymph. Within weeks it will join billions of others in a brief emergence to molt, dry, fly, mate, and die.Adult (imago) Periodical Cicadas. Brood X includes all three species of seventeen-year Periodical Cicadas: Magicicada septendecim, M. cassinii, and M. septendecula. All Periodical Cicadas in the United States are found east of the Great Plains, the lack of trees there prohibiting the expansion of their range further west. Seventeen-year life cycles account for twelve of the fifteen broods of Periodical Cicadas; the balance live for thirteen years. The range of Brood X includes the lower Susquehanna basin and parts of Delaware, Georgia, Illinois, Indiana, Kentucky, Maryland, Michigan, New Jersey, Ohio, Tennessee, Virginia, West Virginia, and the District of Columbia. (United States Department of Agriculture/Agricultural Research Service image)The flight of Periodical Cicadas peaks in late-May and June. Shown here is the Swamp Cicada (Neotibicen tibicen), an “Annual Cicada” that emerges later in the season, peaking yearly during July and August.
The woodlots of the Lower Susquehanna River Watershed won’t be quiet for long. Loud choruses of male Periodical Cicadas will soon roar through forest and verdant suburbia. They’re looking for love, and they’re gonna die trying to find it. And dozens and dozens of animal species will take advantage of the swarms to feed themselves and their young. Yep, the woods are gonna be a lively place real soon.
Did you say Periodical Cicadas? We can hardly wait!
