Some Background on Cicadas

Cicadas are insects in the order Homoptera that undergo incomplete metamorphosis.  During complete metamorphosis, an egg hatches into a larva (like a caterpillar, beetle grub, or fly maggot) that later pupates (forms a chrysalis, cocoon, or puparium), and metamorphoses into a very different looking adult (like a butterfly, moth, bee, beetle, or fly).  In incomplete metamorphosis, the egg hatches into a nymph that looks a lot like the adult (you see this in cicadas and also grasshoppers, crickets, and cockroaches).  The last time the growing nymph sheds its skin it becomes sexually mature and develops wings.

Cicada nymphs live underground where they suck on plant roots to get food.  If you look at a dead cicada you can see a long pointed mouthpart like a syringe.  (Live cicadas, by the way, cannot bite and are harmless.) After living underground for a few years (some stay under for as long as 17!), the nymph matures and tunnels up to the surface.  You’ve probably seen holes in your yard where cicadas have popped out.  The nymph crawls along until it gets to a tree, where it climbs up, then emerges from its skin as a sexually mature adult.  With a little effort you should easily find some empty skins in your neighborhood attached to trees and walls.  Adults live for about a month, sucking on plant juices by piercing the thin bark of twigs.

Males make their calls by using special structures called  tymbals.  These flat, ribbed membranes can be pulled in by a muscle until they click.  When the muscle relaxes, the membrane flips back to its original position, making another click (I’m reminded of the pressure lids on some jars that click when you pop them in and out with your thumb).  That’s why all of the calls you hear have a pulsating quality to the song.  The abdomen has hollow cavities that allow the sounds to resonate, and two “tympanum” membranes that vibrate and amplify the sounds.  Each tympanum is covered by a flap called an “operculum” which is important in identification, as you will see later.  The size and shape of the operculum helps modify the sound, as well as contractions of the abdomen that take place as the cicada sings.

The calls of the males attract females.  After mating, the females lay eggs in the bark of limbs or twigs.  The eggs hatch into tiny nymphs that fall to the ground and then burrow downward until they find an acceptable root.  The life cycle then repeats. 

Key to seven common cicadas near Charlotte, N.C. 

Northern Dusk-singing (Megatibicen auletes), Lyric (Neotibicen lyricen), Swamp (Neotibicen tibicen), Eastern Scissor-grinder (Neotibicen winnemana), Robinson’s (Neotibicen robinsonianus), Linne’s (Neotibicen linnei), and Davis’s Southeastern Dog-day (Neotibicen davisi).

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Note: for some general background on cicadas, see cicada background.

To identify a specimen, begin by determining its sex.  The abdominal segments in female cicadas are all about the same width.  In male cicadas, the first segment is thin and the second is wider than all the rest.  It’s wide in the male because it’s this segment that forms the large chamber in the abdomen that amplifies the sound of its call.  Females don’t call. 

Figure 1.  The arrow is pointing to the wide second abdominal segment in a male cicada.

Males also have two protective coverings called “opercula” on their undersurface that lie overtop their tympana, which vibrate when the males make sound (singular: operculum; tympanum)

Figure 2.  The black arrow is pointing to one operculum of an Eastern Scissor-grinder Cicada.

Now use the key that follows to identify the species of the cicada you’re interested in.  As you do so, be aware that there's a lot of variation among cicadas within the same species.  Your specimen does not have to be a perfect match with the description, or the photos that have been posted.

1. Total length (including wings) roughly 6 cm (2.5 inches) or greater, wing length greater than 5 cm (2 inches), body with portions pruinose (covered with powdery white material above and below). Northern Dusk-singing Cicada (Megatibicen auletes)  Click here to hear its call.

1. If not as above, choose between the two statements numbered 2.

2. Pronotal collar entirely black (Figure 3). Choose between the two statements numbered 3.

2. Pronotal collar entirely green, or green along the posterior half and black along the anterior half.  Choose between the two statements numbered 4.

Figure 3.  The arrows in the photos below are pointing to the pronotal collar, a narrow band making up the posterior edge of the pronotum (the body segment behind the head), and the mesonotum (the plate along the back that covers the mesothorax, to which the wings are attached).

3.  Specimen has bright mint-green legs and a light brown stripe down the center of the underside of the abdomen, which is most often heavily “pruinose”, or covered with white powdery material (this pruinosity might be absent in weathered specimens, exposing a narrow black stripe roughly 1 mm wide).  Males with long oblong opercula, extending roughly halfway down the abdomen.  Swamp Cicada (Neotibicen tibicen)  Click here to hear its call.

3. Specimen has reddish-brown legs and a shiny black stripe down the center of the underside of the abdomen (roughly 5 mm; ¼ inch wide).  Males have brown opercula that are shorter than that of the Swamp Cicada, described above.  The pronotum is primarily black, except for a brown stripe in its center that runs along the anterior / posterior axis of the cicada, and often spreads laterally along the posterior edge, forming a marking that looks somewhat (appropriately) like an inverted music stand.  Lyric Cicada (Neotibicen lyricen engelhardti shown below)  Alternatively, the "music stand" described above might be less pronounced and the pronotum might carry green, brown, or tan markings (Neotibicen lyricen lyricen no photograph shown - I've never seen one in Mecklenburg County)  Click here to hear its call.

4. Body length (excluding wings) is longer than 3.2 cm (11⁄4 inch) AND the bottom (ventral) surface of the abdomen has a brown stripe AND the top surface of the abdomen (dorsal) is black mixed with brown areas. Be careful, some young specimens with black dorsal abdominal surfaces have a golden powder that obscures it. This powder can be rubbed off with a brush. A thin black line might be running through the brown stripe on the ventral surface, but the majority of the stripe is brown. Eastern Scissor-grinder Cicada (Neotibicen winnemana)  Click here to hear its call.

4. Not like above and smaller than 3.2 cm (11⁄4 inch). Might be longer than 3.2 cm, but if so, the bottom surface of the abdomen has a shiny black stripe, and the top abdominal surface is shiny black. Choose between the two statements numbered 5.

5. Body length is 3.2 cm or greater AND the pronotal collar is bisected into left and right halves by a vertical line in its middle. In males, the opercula are short, with a rounded margin along the posterior edge, and tan in coloration. Being rounded, the edges of the opercula form two evenly curved loops, somewhat like those in a cursive letter “w”. Robinson’s Cicada (Neotibicen robinsonianus)  Click here to hear its call (don't be misled by the map at this website, they're common in the Charlotte area).

5. If the insect does not have the combination of characters described above, choose between the two statements numbered 6.

6. If male, the opercula are less rounded than described above. Instead the edges toward the sides of the body are drawn into a blunt point, not in evenly curved loops, AND unlike above, there is black on the opercula in addition to tan coloration. They’re also long enough to cover the first couple abdominal segments. When looking at the insect from directly overhead the margin of the top of the head might be wavy (due to bumps created by the eyes and the central mouthpart apparatus), but overall rather flat – the only “curve” caused by the curvature of the two eyes (see comments below for Davis’s and Figure 4). Linne’s Cicada (Neotibicen linnei)  Click herer to hear its call.

6. When looking at the insect from directly overhead, unlike above, the margin of the top of the head should make a gentle smooth arc, not creating a flat and wavy profile (Figure 4). A small cicada, with a total length including wings usually less than 4.5 cm (13⁄4 inch), sometimes much smaller. The opercula of males are tan and rounded. Davis’s Southeastern Dog-day Cicada (Neotibicen davisi)  Click here to hear its call.

Figure 4.  Photo showing the smooth arc of the head margin of Davis's Southeastern Dog-day Cicada (2 on left) with the more irregular margin of Linne's Cicada (2 on right).

notes:  All photos are mine, except Figure 3, courtesy of Bill Reynolds, of the NC Museum of Natural Resources.  Thanks to Bill also for his suggestions and review of this key.  The key is based on about 100 dead specimens I've found in Charlotte.  I say "near Charlotte" in the title because I'm aware that the species vary widely, even over short geographical distances.  Thanks also to Lang Elliott and Wil Hershberger for their online recordings.  Any comments are welcome.  If you fail in keying out a specimen please let me know so I can make changes.