A Natural History of Conewago Falls—The Waters of Three Mile Island
Cicadas
CICADAS
of the Lower Susquehanna River Watershed
Classified using traditional taxonomic ranks.
Domain-Eukaryota
Kingdom-Animalia
Phylum-Arthropoda
Class-Insecta
Order-Hemiptera
Family-Cicadidae
“Annual Cicadas”
Species with life cycles ranging from 2 to 5 years duration.
Each summer, usually beginning in July, a portion of the nymphs from a population of each species of annual cicada found in a given area emerge from their subterranean habitations among the tree roots. They’ve been there, feeding on small quantities of xylem sap, for the preceding 2 to 5 years. The larvae immediately ascend tree trunks or other sturdy surfaces, climb out of their translucent skin called an exuvia, dry their wings, and take flight.
An adult Eastern Scissor Grinder (Neotibicen winnemanna) and its exuvia hours after emergence. Blood surging into the wings has expanded them for flight while flow throughout the remainder of the body has darkened this cicada’s dorsal color from pale green to a mix of dark greens, browns, and black.
About a week after emerging, adult male cicadas reach full maturity and begin flexing their drum-like organs called tymbals (located just posterior of the wing roots) to generate the sounds that will attract potential mates. To help direct these vocalizations toward a suitable partner, each cicada species has its own unique song.
After breeding, females insert the fertilized eggs into a 2 to 3-inch slit they make using their ovipositor to slice into a 3/16 to 1/2-inch diameter tree branch. Upon hatching, the larvae start chewing their way out of the twig, then tumble to the ground, whereupon they disappear into the soil and commence feeding upon xylem sap as the latest generation of cicada nymphs maturing in a secretive underground hideout.
“Annual Cicadas” of the Lower Susquehanna River Watershed
5 Species
Neotibicen canicularis—(Dog-day Cicada)
Neotibicen linnei—(Linne’s Cicada)
Neotibicen lyricen—(Lyric Cicada)
Neotibicen tibicen—(Swamp Cicada)
Neotibicen winnemanna—(Eastern Scissor Grinder)
Neotibicen canicularis—(Dog-day Cicada)
The smallest of our annual cicadas, the Dog-day Cicada (Neotibicen canicularis) has a slight but obvious bend at the midpoint on the leading edge of the wings and a green pronotal collar between the thorax and the pronotum located just behind the head. In the Lower Susquehanna River Watershed, N. canicularis is most common in more mountainous terrain, often in forests containing at least some conifers. The Dog-day Cicada’s song is a steady high-pitched buzz reminiscent of the sound made by a saw cutting wood in a distant planning mill. (Image by ScaldingHotSoup, under license: CC BY-SA 3.0)
Neotibicen linnei—(Linne’s Cicada)
Like the Dog-day Cicada, Linne’s Cicada (Neotibicen linne) has a gentle bend at the midpoint on the leading edge of the wings as well as a green pronotal collar, but is usually larger. Differentiate the two species by their songs. Linne’s Cicada begins with a soft buzz followed by a salt shaker-like series of pulsating notes, then ending in another soft buzz. Its duration is about 15 seconds. Listen for it in deciduous woods and suburbia. (Image by Bruce Marlin, under license: CC BY-SA 4.0)
Neotibicen lyricen—(Lyric Cicada)
The Lyric Cicada (Neotibicen lyricen) has a curved leading edge on the wings with no significant bend. Though usually colored with a pattern of green, brown, and black, some populations or individuals may have an all-dark, Darth Vader-like appearance. Regardless of color variation, nearly all N. lyricen have a black pronotal collar between the pronotum and thorax. The Lyric Cicada occurs in deciduous forests, farm woods, and residential neighborhoods. Its song is a buzzy, rattling trill with no pulsations and its duration is between 30 and 60 seconds, sometimes longer. (Image by Robert Webster/xpda, under license: CC BY-SA 4.0)
Neotibicen tibicen—(Swamp Cicada)
Neotibicen tibicen, the Swamp Cicada, is often the easiest of the annual cicadas to observe during the mature adult phase of their lives. They often spend their time in the lower branches of trees or among shrubs and other stout vegetation.The Swamp Cicada can be recognized by the gently curved leading edge of the wings and mostly dark appearance, usually including a black pronotal collar, but a greenish pronotum between it and the head.The Swamp Cicada does the majority of its singing before midday, becoming more difficult to detect than the other species during hot afternoons. Hence, another common name for N. tibicen is “Morning Cicada”. The song, about 15 seconds in duration, begins as a soft buzz, then builds in volume to a pulsating drone before tapering off and abruptly ending.
Neotibicen winnemanna—(Eastern Scissor Grinder)
In the lower Susquehanna valley, the Eastern Scissor Grinder (Neotibicen winnemanna) is most common in the woods, parks, and suburbs of the Piedmont Province. In these populations, the leading edge of the wings show a slight-but-noticeable angle at their midpoint.The Eastern Scissor Grinder is one of our species of annual cicadas with a green pronotal collar between the head and thorax.Eastern Scissor Grinders, 3 males (left) and 2 females (right), showing the variability of dorsal coloration.Eastern Scissor Grinders, 3 males (left) and 2 females (right). Note the dark median line on the white abdomen.In an effort to attract receptive females with which he can mate, the male Eastern Scissor Grinder begins singing during the late morning and often continues until near nightfall. The song is a slow pulsating drone, building in volume, then usually ending with an extended slur note.
“Periodical Cicadas”
Species with typical life cycles of either 13 or 17 years duration.
Within a given geographic range, nearly all adult emergence is synchronized to occur in unison with other members of the same brood at either a 13 or 17 year interval.
Adult emergence occurs as the ground temperature reaches approximately 64 degrees Fahrenheit at about 6 to 10 inches depth, usually beginning anytime from late April to early June.
A periodical cicada nymph excavates its way toward the ground’s surface from its feeding area among the tree roots where it spent its last seventeen years. During this prolonged period, it continuously consumed xylem sap, but at rates insignificant to the vitality of its host tree(s). Within about a month, it joined the Brood X emergence of 2021 to transform into a flying adult, mate, and soon thereafter die.Late April, 2021- Beneath the Chestnut Oak where they had been feeding for the preceding seventeen years, at least one dozen Brood X Periodical Cicada nymphs have tunneled into this pre-emergence position under a sun-warmed rock.A periodical cicada nymph reaching maturity. Note the wings and red eyes. Within weeks it will join billions of others in a brief adult emergence to fly, mate, and then die.About a week after emerging from their exuviae, adult male cicadas reach full maturity and flex their drum-like organs called tymbals (located just posterior of the wing roots) to generate the sounds that will attract potential mates. Among periodical cicadas, choruses of these songs can include thousands of males joining in unison to achieve volumes that carry for a quarter of a mile or more. Having attracted a receptive female, this male “Pharaoh Periodical Cicada” is copulating with its mate. It is the climax event for the long lives that will come to an end within less than a month.Map showing the range and emergence years for each of the three broods of 13-year and twelve broods of 17-year Periodical Cicadas. Periodical cicadas occur only in the eastern half of North America. Click the image for a larger map. (United States Forest Service image)
Each 13-year Periodical Cicada is classified in a species group with a 17-year Periodical Cicada. Cicadas in a species group share behavioral and morphological traits and are descended from a common ancestor in the same group.
Species group -decim
Species group -decim includes Magicicada tredecim and Magicicada neotredecim along with the 17-year Periodical Cicada Magicicada septendecim, the “Pharaoh Periodical Cicada”.
Species group -cassini
Species group -cassini includes Magicicada tredecassini along with the 17-year Periodical Cicada Magicicada cassini, “Cassini’s Periodical Cicada”.
Species group-decula
Species group -decula includes Magicicada tredecula along with the 17-year Periodical Cicada Magicicada septendecula, a species sometimes called “Little Seventeen-year Cicada”.
17-year Periodical Cicadas
3 Species
(All are found in the Lower Susquehanna River Watershed)
Magicicada septendecim, the “Pharaoh Periodical Cicada”, a species also known as “Linnaeus’ Seventeen-year Cicada” or, more colloquially, the “Seventeen-year Locust”, has an orange patch between the eye and the root of the wings.The underside of the Pharaoh Periodical Cicada’s abdomen has orange bands or stripes along the trailing edge of each segment. The width of the bands can vary, but is typically wider on males (left) than on females (right).The “Pharaoh Periodical Cicada” is the largest of the 17-year Periodical Cicadas.
Magicicada cassini—(“Cassin’s Periodical Cicada”)
The thorax of Magicicada cassini, “Cassin’s Periodical Cicada”, a species also known as the “Dwarf Periodical Cicada” or “Morris’ Seventeen-year Cicada”, is black between the eye and the wing insertion.In both the male (left) and female (right), the underside of the Cassin’s Periodical Cicada’s abdomen is all black without orange bands or stripes.
The thorax of Magicicada septendecula, a species informally known as the “Little Seventeen-year Cicada”, is all black between the eye and root of the wings.The underside of the abdomen on Magicicada septendecula.
Brood X Periodical Cicadas in the Lower Susquehanna River Watershed
Map showing flights dates of adult periodical cicadas in the lower Susquehanna valley and surrounding regions. Upcoming events include the emergences of Broods XIV (2025), II (2030), and X (2038). (United States Forest Service base image)
The following content is a copy of the susquehannawildlife.net post from June 3, 2021, describing the emergence of Brood X Periodical Cicadas in the Lower Susquehanna River Watershed. It includes a description of each of the three species included in the flights of the 17-year broods.
Identification of the Three Species of Brood X Periodical Cicadas
The emergence of Brood X Periodical Cicadas is now in full swing. If you visit a forested area, you may hear the distant drone of very large concentrations of one or more of the three species that make up the Brood X event. The increasing volume of a chorus tends to attract exponentially greater numbers of male cicadas from within an expanding radius, causing a swarm to grow larger and louder—attracting more and more females to the breeding site.
Holes in the ground where emerging Brood X Periodical Cicadas have come to the surface.Having ascended the trunk of this Eastern White Pine after emerging from the soil, massive numbers of periodical cicadas have left behind hundreds of opaque exuviae. The exuvia is the exoskeletal remains of the cicada’s final molt from a nymph into a flying adult.A freshly molted Magicicada cassini periodical cicada.
Each periodical cicada species has a distinctive song. This song concentrates males of the same species at breeding sites—then draws in an abundance of females of the same species to complete the mating process. Large gatherings of periodical cicadas can include all three species, but a close look at swarms on State Game Lands 145 in Lebanon County and State Game Lands 46 (Middle Creek Wildlife Management Area) in Lancaster County during recent days found marked separation by two of the three. Most swarms were dominated by Magicicada septendecim, the largest, most widespread, and most common species. However, nearly mono-specific swarms of M. cassini, the second most numerous species, were found as well. An exceptionally large one was northwest of the village of Colebrook on State Game Lands 145. It was isolated by a tenth of a mile or more from numerous large gatherings of M. septendecim cicadas in the vicinity. These M. cassini cicadas, with a chorus so loud that it outdistanced the songs made by the nearby swarms of M. septendecim, seized the opportunity to separate both audibly and physically from the more dominant species, thus providing better likelihood of maximizing their breeding success.
Some of the tens of thousands of M. cassini periodical cicadas in a concentration on State Game Lands 145 northwest of Colebrook in Lebanon County, Pennsylvania. This swarm occupied deciduous and evergreen trees on several acres of a south-facing hillside. To provide protection from predators and assure the chance of finding a mate “in the crowd”, lesser numbers of this and the rarer species, Magicicada septendecula, would need to merge into the swarms of the abundant M. septendecim periodical cicadas to breed.
The process of identifying periodical cicadas is best begun by listening to their choruses, songs, and calls. After all, the sounds of cicadas will lead one to the locations where they are most abundant. The two most common species, M. septendecim and M. cassini, produce a buzzy chorus that, when consisting of hundreds or thousands of cicadas “singing” in unison, creates a droning wail that can carry for a quarter of a mile or more. It’s a surreal humming sound that may remind one of a space ship from a science fiction film.
Listen to the songs of individual cicadas at close range and you’ll hear a difference between the widespread M. septendecim “Pharaoh Periodical Cicada” and the other two species. M. septendecim‘s song is often characterized as a drawn out version of the word “Pharaoh”, hence one of the species’ common names (another is “Seventeen-year Locust”). As part of their courtship ritual, “Pharaoh Periodical Cicadas” sometimes make a purring or cooing sound, which is often extended to sound like kee-ow, then sometimes revved up further to pha-raoh. M. cassini, often known as “Cassin’s Periodical Cicada” or “Dwarf Periodical Cicada”, and the least common species, M. septendecula, often make scratchy clicking or rattling calls as a lead-in to their song. Most observers will find little difficulty locating the widespread M. septendecim “Pharaoh Periodical Cicada” by sound, so listening for something different—the clicking call—is an easy way to zero in on the two less common species.
To penetrate the droning choruses of large numbers of “Pharaoh” and/or “Cassin’s Periodical Cicadas”, sparingly distributed M. septendecula cicadas have a noise-penetrating song consisting of a series of quick raspy notes with a staccato rhythm reminiscent of a pulsating lawn sprinkler. It can often be differentiated by a listener even in the presence of a roaring chorus of one or both of the commoner species. However, a word of caution is due. To call in others of their kind, “Cassin’s Periodical Cicadas” can produce a courtship song similar to that of M. septendecula so that they too can penetrate the choruses of the enormous numbers of “Pharaoh Periodical Cicadas” that concentrate in many areas. To play it safe, it’s best to have a good look at the cicadas you’re trying to identify.
M. cassini Periodical Cicadas “singing” from a treetop at Colebrook, Lebanon County, Pennsylvania. Clicking phrases are sure sign of the presence of this species and/or M. septendecula, the least likely of the three species to be encountered. When in close proximity to a swarm, a listener will often notice the rising and falling volume of a chorus in a cycle that repeats every few seconds, an effect caused by cicadas attempting to synchronize their songs in a harmony with others in the group. When courtship and mating is complete, female periodical cicadas will begin laying eggs in slits made in fresh new growth at the ends of branches on deciduous trees like the one seen here.
Visually identifying Brood X Periodical Cicadas to the species level is best done by looking for two key field marks—first, the presence or absence of orange between the eye and the root of the wings, and second, the presence or absence of orange bands on the underside of the abdomen. Seeing these field marks clearly requires in-hand examination of the cicada in question.
Observing a perched Brood X Periodical Cicada can sometimes provide a view of the key field marks needed for identification of the species. On the M. septendecim “Pharaoh Periodical Cicada” seen here, the orange patch between the eye and wing root and the orange bands on the underside of the abdomen are visible.The abdomen of this perched M. cassini “Cassin’s Periodical Cicada” appears, when viewed through the wings, to have orange bands. But, examination in hand would show an all-black abdomen with glossy surfaces shining in the sunlight. For accuracy, the up-close-and-personal look is necessary.In the hand, cicadas can be better studied for key field marks. M. septendecim (top) is larger than M. cassini (bottom) and M. septendecula, but the difference is not always apparent, particularly when a direct comparison cannot be made.
To reliably separate Brood X Periodical Cicadas by species, it is necessary to get a closeup view of the section of the thorax between the eye and the root (insertion) of the wings, plus a look at the underside of the abdomen. Here’s what you’ll see…
M. septendecim has an orange patch between the eye and the root of the wings.The underside of M. septendecim’s abdomen has orange bands or stripes along the trailing edge of each segment. The width of the bands can vary, but is typically wider on males (left) than on females (right).
Magicicada cassini—“Cassin’s Periodical Cicada”
The thorax of M. cassini is black between the eye and the wing insertion.In both the male (left) and female (right), the underside of M. cassini’s abdomen is all black without orange bands or stripes.
Magicicada septendecula
M. septendecula’s thorax is black between the eye and root of the wings.The underside of M. septendecula’s abdomen has narrow orange bands or stripes along the trailing edge of each segment. The width of the bands can differ. Those of this male (left) are minimal and the bands on this female (right) are near the maximum for the species.
There you have it. Get out and take a closer look at the Brood X Periodical Cicadas near you.
The abundant and widespread “Pharaoh Periodical Cicada” (M. septendecim).Accumulating remains of M. cassini “Cassin’s Periodical Cicadas” beneath an Eastern White Pine at the site of the Colebrook State Game Lands swarm.
