Book Review: The Cicadas of North America

Chris Alice Kratzer begins her new book with a deeply personal memory and dedication, then proceeds to deliver another comprehensive treatment of a common, yet complex, category of insects: cicadas. The book is the second for Kratzer, whose debut work was The Social Wasps of North America. With memories of this spring’s periodical cicada event still fresh in the public mind, this book could easily eclipse the wasp book in popularity, but both volumes deserve your attention.

The Cicadas of North America is essentially a monograph of all members of the family Cicadidae found north of South America. The scientific community should certainly respect it as such. If this sounds intimidating for non-scientists, you need not fear. Kratzer is a master science communicator, with sincere empathy for those of us who avoided hardcore subjects in high school and college.

Part of the genius in her approach is that she is self-publishing through Owfly Publishing, a subsidiary of her company Owlfly, LLC. This allows her to set her own limits, if any, and prioritize what she sees as most important for her audience. She takes creative license that serves to enhance the readability and overall presentation of the book. The digital artwork alone is enough to recommend the book, but wait, there is more.

Kratzer’s trademark continues to be exceptionally thorough coverage of background information on life cycle, anatomy, evolution, classification, ecological relationships, and impacts on humanity, both positive and negative, past and present. Even if cicadas are not your favorite insect (but really, why are they not?), you will find yourself referring to the front of the book for understandable explanations of genetics, taxonomy, and other scientific concepts that apply broadly across all organisms.

Once again, Kratzer expands her region of focus to include Latin America as, ideally, all such manuals should in the interest of geographic accuracy that respects biomes but not borders. This might be the final nudge I need to renew my passport. I mean, look at that Sparse Emerald Cicada, Zammara smaragdula. A turquoise cicada (it is on the cover, too)?

Each digital rendering is split from left to right to show the degree of variation in color, density of markings, and other morphological features to help identify a specimen of either form. Some species are treated twice if they exhibit strong regional differences, with corresponding range maps delineating their geographic distribution. Everyone contributing reference photos, and community science records resulting from those images, is acknowledged on each species page.

If you are a stickler for minute details, and/or get hooked on studying cicadas yourself, the “taxonomic notes” in the back of the book give you the most current assessment of the standing of various species. Kratzer readily admits that what is in the book could be wrong, but there is no argument as to how much is completely unknown to anyone, at least in the community of Western scientists. The book is thus both a treatise and a booster designed to ignite further research.

If I sound like a paid shill, or an infomercial, I hope I can be forgiven for my enthusiasm for a quality example of natural history literature. Meanwhile, I hope Kratzer continues turning out more such references for whatever creatures catch her fancy. I’m subscribed to the Owlfly newsletter, so I should be among the first to know.

The Cicadas of North America is a hefty 573 pages, retails for $27.99 U.S., from the publisher, and is shipped in sustainable packaging from EcoEnclose. You can request a signed copy when you order.

Welcome to Brood IV (Periodical Cicadas)

My wife and I scheduled our recent visit to see her parents in Leavenworth, Kansas specifically around the time when Brood IV of the periodical cicadas (Magicicada spp.) would be emerging, singing, and laying eggs. By all historical accounts, we should have timed it almost perfectly. Unfortunately, brutal weather turned that particular goal into an almost total bust.

At any given locality in the eastern United States, Magicicada emergences happen only every 13 or 17 years. Scientists remain puzzled by the potential reasons for such a sporadic, synchronous spectacle in which millions of cicadas erupt from their underground lair to shed their youthful exoskeletons for winged adulthood.

Different populations of periodical cicadas, also known as 17- or 13-year "locusts," have been assigned Roman numerals denoting "broods." Each brood has an emergence on a thirteen or seventeen year cycle. The thirteen-year cicadas typically range in the south, while seventeen-year broods occur mostly in the north. There is usually more than one species represented in each brood. This is an extra-special year because both the 17-year Brood IV and the 13-year Brood XXIII are emerging. This happens once every 221 years.

A shed exoskeleton

Brood IV ranges from southwest Iowa and southeast Nebraska through western Missouri, Eastern Kansas, much of Oklahoma, and extreme northern Texas (eastern half). Brood XXIII emerges from Illinois and southwest Indiana to Louisiana, following the Mississippi River valley.

Initial observations of periodical cicadas by early settlers in 1633 were rife with errors. Those mistaken beliefs were repeated in a 1666 English publication. The only such massive appearances of a single kind of insect that the colonists were familiar with were plagues of migratory grasshoppers, so they assumed that the cicadas, too, were "locusts," hence the incorrect label that has persisted to this day.

Cicadas are actually true bugs in the order Hemiptera, suborder Auchenorrhyncha. Leafhoppers, treehoppers, and planthoppers are all related to cicadas. They all have piercing-sucking mouthparts with which they tap plant juices for food. Despite their overwhelming numbers, periodical cicadas do remarkably little damage in either the nymph or adult stage.

Damage to trees occurs when the female cicada forces her spear-like ovipositor into a twig or branch to lay her eggs. She does this with enough force that it can snap the twig, causing the foliage beyond the break to die and turn prematurely yellow or brown. This phenomenon is called "flagging." It also occurs when more than one female oviposits in the same twig.

Tiny cicada nymphs hatch from these eggs and plummet to the ground where they immediately dig into the soil. There they will spend the next thirteen or seventeen years (depending on the species), feeding on the roots of trees, shrubs, and other plants. At the end of their underground life they surface, sometimes erecting "chimneys" above the surface of the soil. They clamber out, and up the nearest vertical object. Their front legs are like grappling hooks, and they secure themselves to the object. The exoskeleton then splits down the back and out comes a fledgling adult cicada. It is white, with patches of black across the thorax, and bright red eyes. The wings inflate in a matter of minutes, but it takes hours for the new exoskeleton to harden and the black and orange pigments to fully manifest.

Male cicadas have a pair of percussion organs inside their abdomen, and opening on the underside of the insect. They can generate a very loud "song" in this manner and, obviously, the more cicadas the louder the concert. The adult insects live just long enough to procreate before falling victim to predators, a parasitic fungus, sheer exhaustion, or old age.

There are three species of Magicicada with a 17-year cycle, and four species with a 13-year cycle. One of these thirteen-year species, M. neotredecim, was only discovered in the year 2000. The songs of the different species differ perhaps more than the physical appearance of the insects.

There are at least 9 shed exoskeletons in this image

When we happened upon Brood IV in northwest Missouri, the emergence had barely begun. We saw numerous shed exoskeletons, but found only four or five adult specimens, one only hours old. Meanwhile, there was evidence of rampant predation by birds. There were wing fragments everywhere. What a disappointment. Only a week later, I am receiving reports from friends that the emergence has finally overwhelmed mortality factors, and males are forming choruses.

I have no idea when I will get another opportunity to document a Magicicada brood in the manner I want to for all of my readers here. Thankfully, there are plenty of other resources online, including the "Cicada Mania" website, the "Periodical Cicada Page" produced by the University of Michigan, and "Cicada Central,", a project of the University of Connecticut.

Grand Western Cicada

On this “True Bug Tuesday,” with Christmas carols seemingly always within earshot, I harken back to summer and the melodic sounds of cicadas. Ok, maybe “blaring noise” is a truer description of those members of the genus Tibicen that were omnipresent during our visits to Ohio, Iowa, and Kansas this year. One of the more impressive species we saw was the “Grand Western Cicada,” Tibicen dorsatus.

T. dorsatus is also known as the “Bush Cicada” and “Splendid Prairie Cicada.” Indeed, it is most abundant in remnants of tallgrass and shortgrass prairie, and savannah-like habitats in the Great Plains states east of the Rocky Mountains and west of the Mississippi River. Scattered records are also known as far east as Indiana. Few populations exist north of Wyoming and southern South Dakota.

This species is one of the so-called “annual” cicadas. That term translates to at least some individuals of a given species emerging as adults every year, even though the life cycle still takes about five years or more to complete. So, emergences are staggered, not synchronized as is the case with the periodical cicadas of the genus Magicicada. Annual cicadas also emerge later in the season than their synchronous relatives. Look for T. dorsatus in July, August, and September (as early as June in some southern latitudes).

The fact that annual cicadas are frequently heard during the hottest part of the summer and fall has lent them additional labels of “dog day cicadas” and “harvestflies.” They also present themselves during the hottest times of the day, depending on the species, adding a literal, audible sizzle to the infernal temperature.

Only male cicadas produce sound, and they do so internally. Most of the abdomen of a male cicada is occupied by two large cavities, each opening on the underside but covered by a lid-like “operculum.” Inside, a large muscle in each chamber can be vibrated at high speed, producing a sound that is amplified and projected outward as the insect contorts its body. The Little Drummer Boy has nothing on these guys.

Most of a cicada’s life is spent underground, of course, living as a hunchbacked nymph sucking plant sap from roots of trees and shrubs and other plants. That diet doesn’t foster rapid growth, and it therefore takes the insect a long period of time to mature. Eventually it does so, though, and claws its way to the soil surface, usually under cover of darkness, to complete its metamorphosis.

As soon as the nymph extracts itself from the ground, it seeks in earnest the nearest vertical object. Climbing to an adequate height (perhaps an individual decision rather than a hard-wired instinctive one) it digs in and splits its exoskeleton down the middle of its back. A soft, pale insect with stubby wings pulls itself out with great effort.

Many cicadas must perish in the act of this final molt, becoming tangled in their own “skin,” or simply not having enough energy to complete the ordeal. Others come out imperfect, unable to fly or with malformed legs. Those that do manage to struggle out of their old selves then hang quietly while the wings inflate and pigments begin to manifest themselves in the otherwise ghostly creature.

Once hardened, cicadas are durable insects. I once saw a Blue Jay catch a cicada in Cincinnati, Ohio, try to hammer it to death on a utility wire, only to have the insect slip out of its beak and fly away.

The Grand Western Cicada is one of our larger species, measuring around 57 millimeters (2.5 inches) from “nose” to the tips of its folded wings. The decorative white markings are actually waxy, and can rub off. The waxy substance also covers the belly of the insect, and cicadas often orient themselves belly-up to the sun so as to prevent becoming overheated.

While many cicada species also call from the canopy of trees, where they are shaded, the Grand Western Cicada often perches low on vegetation where it tends to be more exposed. Despite its contrasting coloration, it is surprisingly cryptic.

Another, very similar species, Tibicen tremulus, has recently been described. Its range overlaps with that of T. dorsatus, and the only way to easily segregate the two in the field is by differences in their songs.

This last summer was apparently a good year if you like cicadas. They were very abundant in the Midwest U.S. If you missed their diversity and concerts, keep an ear cocked for them next year.

Sources: Bartlett, Troy, et al. 2013. “Species Tibicen dorsatus - Bush Cicada,” Bugguide.net.
Cranshaw, Whitney, and Boris Kondratieff. 1995. Bagging Big Bugs: How to Identify, Collect and Display the Largest and Most Colorful Insects of the Rocky Mountain Region. Golden, CO: Fulcrum Publishing. 324 pp.
Hill, Kathy, and David C. Marshall. 2013. Insect Singers.
Salsbury, Glenn A. and Stephan C. White. 2000. Insects in Kansas (3rd Edition). Topeka, KS: Kansas Department of Agriculture. 523 pp.

Cicada shells

Almost every summer I receive several questions about strange bugs sitting motionless on fence posts, tree trunks, and other upright objects. I thought I would do an entry here to explain the mystery.

The descriptions of the creature that people give to me vary from a “cross between a crayfish and a beetle,” to “gnome-like,” and all mention the large claws on the “front end.” No one has ever seen anything like it, and it is no wonder. Normally, the creature they are seeing lives fairly deep underground.

I have taken to calling these bugs “former insects,” since the objects being seen are not entire insects but the cast exoskeletons (“skins”) of cicadas, family Cicadidae. Scientists call these shed skins “exuviae,” all that remains behind when the insect molts from the nymph stage into an adult. Dragonflies, damselflies, stoneflies, and mayflies also leave behind these ghostly but tangible shadows of their former selves.

The average person rarely sees an animated version of a cicada nymph because the mature nymphs emerge from the soil at night, climbing the nearest vertical surface, and then splitting the exoskeleton down the middle of the back to allow the escape of the wet, soft adult under the cover of darkness. The fresh, pale adults are extremely vulnerable, but their principle predators are diurnal, so they avoid instant death by coming out at night. Cicadas are large insects, so they can be quite conspicuous under the best of cryptic circumstances.

An adult "annual" cicada, Neotibicen sp.

Most people in eastern North America see the shells of “annual” or “dog day” cicadas in the genus Tibicen. They then hear the loud “songs” of the adult male cicadas, not often seeing the insect that makes such a racket. Despite the name, annual cicadas still take a long time to grow up. They live a subterranean existence as nymphs, sucking the sap from tree roots for at least five to seven years. The generations are staggered, though, so some adults emerge every summer. This is in contrast to the synchronous broods (populations) of the periodical cicads or “17-year locusts” that emerge en masse in the late spring or early summer every 13 or 17 years, depending on the latitude of the population.

I like to get questions about things like cicada exuviae. It shows that people are observant and curious, two qualities I really admire in my own species