Cicada Mania

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July 12, 2015

Why do Magicicada stay underground for 13 or 17 years?

Filed under: FAQs | Life Cycle | Magicicada | Periodical — Dan @ 8:01 pm

People ask: why do periodical cicadas stay underground for 17 or 13 years?

There are three parts to this puzzle that people are interested in:

  1. How cicadas count the years as they go by.
  2. Why prime numbers? 13 and 17 are prime.
  3. Why is their life cycle so long? They are one of the longest living insects.

Cicadas likely don’t count like people do (“1,2,3,4…”) and you won’t find scratch marks inside the cell (where they live underground) of a Magicicada, marking off the years as they go by. However, there is a kind of counting going on, and a good paper to read on that topic is How 17-year cicadas keep track of time by Richard Karban, Carrie A. Black, and Steven A. Weinbaum. (Ecology Letters, (2000) Q : 253-256). By altering the seasonal cycles of trees they were able to make Magicicada emerge early, proving that cicadas “count” seasonal cycles, perhaps by monitoring the flow and quality of xylem sap, and not the passage of real time.

Why prime numbers, and why is the life cycle so long? This topic fascinates people. The general consensus is that the long, prime-numbered life-cycle makes it difficult for an above-ground animal predator to evolve to specifically predate them. Read Emergence of Prime Numbers as the Result of Evolutionary Strategy by Paulo R. A. Campos, Viviane M. de Oliveira, Ronaldo Giro, and Douglas S. Galva ̃o (PhysRevLett.93.098107) for more on this topic. An argument against that theory is that a fungus, Massospora cicadina, has evolved to attack periodical cicadas regardless of their life cycle. Of course, a fungus is not an animal. Maths are easy for fungi.

There are also questions about why there are 13 and 17 year life cycles, why a 4 year acceleration of a brood might occur1 and why Magicicada straggle.

1 This is a good place to start: Genetic Evidence For Assortative Mating Between 13-Year Cicadas And Sympatric”17-Year Cicadas With 13-Year Life Cycles” Provides Support For Allochronic Speciation by Chris Simon, et al, Evolution, 54(4), 2000, pp. 1326–1336.

30 Things Cicadas Do

Filed under: Eggs | FAQs | Life Cycle — Dan @ 11:59 am

One of the most frequently asked questions we receive is: “what do cicadas do“? This question is similar to the question “what is the purpose of cicadas” — the answers to both questions help people understand why these fascinating, unusual creatures exist at all.

The simplest reduction of their life cycle is:
1) They hatch from an egg.
2) They burrow underground where they will drink from plant roots for most of their lives.
3) They leave the underground and become adults.
4) The males make sounds that attract females.
5) Males & females court & mate.
6) Females lay fertilized eggs in the branches of plants, and the cycle continues.
7) They die.

The specifics of a cicada’s life cycle varies from species to species, but here is a more detailed view of what cicadas do:

From egg to 1st instar nymph:
1) Cicada nymphs hatch from eggs.

Marlatt 1907 Egg Nest Details

2) Nymphs feed on plant fluids which they access thanks to the egg-nest groove made by their mothers.

3) They leave the groove, and drift to the ground. Their descent to the ground doesn’t hurt them because they weigh so little.

4) Once on the ground, they dig into the soil until they find small rootlets, from which they will feed.

Once Underground:
5) Underground, they will tunnel/dig

6) and establish a cell

7) from where they’ll comfortably feed. Cicadas feed on the xylem sap of plants. With the help of bacteria they transform the water, minerals and amino acids found in tree fluids to the tissues of their own bodies.

8) They pee, in fact they seem to use excess plant fluid to moisten soil to help mold the walls of their cells.

9) Throughout their life underground they will move from root to root… as plant root systems change with the seasons, when roots die off, or perhaps to avoid predators.

10) Underground, a cicada may (depending on the species) go through four instars, molting three times (see an image of the four instars).

Preparing to emerge:
11) Cicadas will build a tunnel to the surface of the ground, in preparation for their emergence.

12) Cicadas often take that a step further an build a chimney/turret above ground. This often happens in shady areas or when the ground is muddy.

Once above ground:

13) They emerge from their tunnels

14) Cicadas run as fast as they can…

15) And find a surface perpendicular to the ground, hold tight, and begin to molt…

16) During the molting process (ecdysis), cicadas perform many acrobatic moves to separate themselves from their nymphal skin, including pulling their old trachea from their bodies.

17) Once outside their nymphal skin, they will inflate their wings

18) … and expand various parts of their bodies, like their heads.

19) They will change color.

20) Once their bodies are hard enough (sclerotization counts as a thing they do)…

21) They will either seek shelter, perhaps by crawling up higher along a tree trunk…

22) or if your are a Magicicada, you might stick around in the hopes that a predator will eat you.

Mating and Reproduction:

23a) If you are a Male cicada, you are going to sing… unless you belong to a species that cannot sing, in which case, you’ll move your wings in a way that will produce a sounds.
There are many types of songs: a) distress calls, b) calls to establish territory, c) calls to attract females, d) including choruses of many cicadas and e) courting calls

23b) Female cicadas, and some male cicadas, move their wings to make sounds, also in an effort to attract and engage a mate.

24) Most cicadas (aside from Magicicada during the early days of their adult lives) will try to avoid being eaten by predators.

25) They’ll fly, of course.

26) Cicadas, like Magicicada, will establish chorusing centers, which are places where the male cicadas sing together and females come to meet them.

27) Male and female cicadas will court

28) and mate

29) the female cicada will lay her eggs in grooves (ovipositing) she etches into a suitable plant stem, and we’re back to step 1.

30) The last thing cicadas do, of course, is die, and return the nutrients found in their bodies to the soil, where they will be broken down and absorbed by the plants they fed upon.

Some things cicada do not do:

Here are some things cicadas do not do:

1) They don’t seek shelter during the fall months (i.e. they don’t try to live inside your house), unlike Ladybugs or Stinkbugs.
2) They don’t sting or otherwise pass venom onto people.
3) They don’t chew plant leaves, like caterpillars or grasshoppers.
4) They don’t dump garbage in the ocean.

July 6, 2015

Where do Cicadas Live?

Filed under: FAQs — Dan @ 5:32 pm

Once they become adults, cicadas live on and around plants similar to their host plants, often the very same tree where they were born. Depending on the species of cicada, this could be a tree, or perhaps a grass (sugar cane, which some cicadas use as hosts, are giant grasses).

When they are nymphs, which they are during the first stages or instars of their life, they live underground amongst the root systems of the plants they derive nourishment from. While they are there, they dig tunnels and build cells (their living quarters) where they can feed from the fluid of rootlets of plants in comfort.

July 5, 2015

What are Broods?

Filed under: FAQs | Magicicada | Periodical — Dan @ 6:29 pm

It is important to note that when we talk about cicada broods, we are talking about the 17 & 13-year periodical Magicicada cicadas. We are not talking about Tibicen or other species.

All Broods

There are 12 groups of Magicicadas with 17-year life cycles and 3 groups of Magicicadas with 13-year life cycles. Each of these groups emerge in a specific series of years, rarely overlapping (17 & 13-year groups co-emerge every 221 years, for example). Each of these groups emerge in the same geographic area their parents emerged. These groups, each assigned a specific Roman numeral, are called broods.

Gene Kritsky’s book, Periodical Cicadas: The Plague and the Puzzle, documents the history of the recognition and naming of the broods. The first person to document that different groups of periodical cicadas emerged in different years was Nathaniel Potter in 1839. Benjamin D. Walsh and Charles V. Riley devised the system for numbering the different broods in 1868, and then C. L. Marlatt sorted the 17 year broods out from the 13-year broods, giving us the system we have today.

Visit our Broods page which features a grid of the Brood names, their lifespan, when & where they’ll emerge next and links to maps.

What Might Cause Cicadas to go Extinct?

Filed under: Extinct | FAQs — Dan @ 9:48 am

You might ask, “why were there once cicadas in my area, but now there are none?” There are a number of reasons why cicadas might die off in a particular area, or go totally extinct.

1) Destruction of host trees by a blight or destructive insect infestation. Tibicen bermudiana went extinct in the 1950s in Bermuda because of a cedar tree blight. Emerald Ash Borer insects are currently devastating Ash trees in North America. Ash trees are a favorite tree of Magicicada cassini, in particular.

2) Destruction of host trees by humans. Consider that every time a forest is removed to make room for another neighborhood, factory, strip mall, or highway, the cicadas that inhabited those areas died. Each time the human race expands, the cicadas must decline. The paper The Distribution of Brood Ten of the Periodical Cicadas in New Jersey in 1970 by John B. Schmitt documents the reduction of cicada populations in New Jersey, the nation’s most populous state. Also, the entire Brood XI went extinct in Connecticut as of 1954.

3) Extreme weather such as tornadoes, hurricanes, and flooding can destroy cicada habitat. While there are cases where cicadas were able to survive some pretty horrific weather, if trees are destroyed, or grasses that are hosts to young cicada nymphs are destroyed, or if floodwater sits too long, the cicadas are doomed.

4) Pesticides. It should be obvious that pesticides will kill cicadas.

Can pets or other animals sense cicadas below ground?

Filed under: FAQs — Dan @ 8:51 am

Can pets, including dogs and cats, or other animals sense cicadas below ground? Yes they can. Animals have a better sense of hearing than humans, and they are able to sense the subtle sounds of cicadas tunneling underground.

You might discover animals, including your pet dog, digging up your lawn in advance of a periodical cicada emergence. That is because they can sense the cicadas preparing for the day they will emerge.

Did Someone Offer a Reward for White or Blue-eyed Cicadas?

Filed under: Eye Color | FAQs | Magicicada | Roy Troutman — Dan @ 7:58 am

Is it true that someone has offered a reward for a white or blue-eyed Magicicada cicadas?

This was false and an urban legend until in 2008 when Roy Troutman began to offer rewards for living blue-eyed cicadas for scientific research. All cicadas were released, unharmed.

Important: Roy is no longer offering the reward as he has obtained the cicadas needed for his research. So, don’t bug him, unless you want to tell him that his photos and video are awesome.

White or Blue-eyed Magicicadas cicadas are extremely rare, so finding them can be difficult. I usually find one per emergence, and that is after looking at thousands of cicadas.

Speaking of Roy and White-eyed cicadas, here is a video Roy took of a White-eyed cicada:

And here’s a white and orange-eyed cicada photo taken by Roy:

Upclose on Marble eyed 17 year cicada

Are cicadas attracted to the sound of lawnmowers and other machinery?

Filed under: Behavior | FAQs | Magicicada — Dan @ 7:41 am

Cicadas on Man Are cicadas attracted to the sound of lawnmowers and other machinery? Yes! Cicadas, particularly Magicicada periodical cicadas, are attracted to lawnmowers, weed-whackers, leaf blowers, hedge trimmers, power drills, etc. If it is loud and vibrates, cicadas will be attracted to it. Why? Most likely because they think your tool is a particularly impressive periodical cicada chorusing center, so males want to join in with the chorus and females want to mate with the particularly impressive males.

So, next time you’ve got the old angle grinder out, don’t be surprised if a cicada lands on your shoulder.

When is a locust not a locust? When the locust is a cicada.

Filed under: FAQs | Identify | Magicicada — Dan @ 6:26 am

Are Cicadas Locusts? The short answer is NO. However, in the U.S.A. we’ve been calling cicadas “locusts” for hundreds of years.

People have seen referring to cicadas, particularly Periodical cicadas, as both flies and “locusts” since the 1600’s, when colonists first documented them.

Gene Kritsky's The Plague and the Puzzle

Gene Kritsky’s book Periodical Cicadas: The Plague and the Puzzle provides a chronology and historical texts of people referring to cicadas as “locusts”. Consider this quote from Pehr Kalm from 1756:

By the Englishmen here they are called Locusts and by the Swedes living here, they have gotten the name Grasshoppers. In Latin, they could be called Cicada.

It makes some sense that Englishmen would call cicadas Locusts, and Swedes would call them Grasshoppers because there was only one species of cicada in both England and Sweden. This cicada, Cicadetta montana montana, call is so high-pitched you need electronic assistance to hear it, so most people were not aware of its existence. So, when Englishmen and women encountered cicadas they likely thought “there are a lot of them, they’re big, I’m afraid they’re going to eat my carrots — these must be LOCUSTS”!

Cicadas are indeed not Locusts, Grasshoppers or Flies.

Take a look that the illustration of a true locust below. You’ll notice the true locusts have HUGE rear legs for hopping, long antennae, and relatively long bodies. True locusts chew the plants they consume, while Magicicadas suck fluids from trees.



17-year cicada:

17-year cicada

Characteristic Locust Cicada
Order Orthoptera Hemiptera
Hind Legs Giant hind legs for jumping Hind legs about the same size as other legs; great for climbing and perching.
What they eat Everything green they can find to eat Xylem sap
They’re in your town All the plants in your town have been stripped bare Cool UFO movie soundtrack sounds during the day

For more instances of cicadas being confused with other types of insects, read the article These are not cicada insects!

July 3, 2015

How Long Does a Periodical Cicada Emergence Last?

Filed under: FAQs | Magicicada | Periodical — Dan @ 2:47 pm

People often ask: “how long do cicadas last”, “how long will the cicadas be here”, or “how long do cicadas live above ground”?

People probably ask these questions, sadly, because they are tired of listening to the love songs of these cicadas. Like the saying “it is darkest before the dawn”, however, silence is typically a few weeks away.

The length of a local emergence:

The typical periodical cicada emergence will last between 6 to 8 weeks in a single location, with significant chorusing (singing) lasting about 3 to 4. Cool weather or rain can prolong an emergence.

The research paper Emergence of 13-Yr Periodical Cicadas (Cicadidae: Magicicada): Phenology, Mortality, and Predator Satiation by Kathy S. Williams, Kimberly G. Smith, and Frederick M. Stephen1 contains a wonderful study of the arc of a periodical cicada emergence. The entire emergence event takes place within 8 weeks, from the first emerged cicada to the last dead cicada (see Fig 4 in that document 1). The number of live adults reached its peak within two weeks and then began to die off in significant numbers two weeks after that, due mostly to natural causes. After that, the population of cicadas gradually dwindles due to natural deaths and predation.

Length of the chorusing:

Male cicadas will not begin chorusing at the start of an emergence, for a couple of reasons: 1) the first cicadas to emerge, which are primarily males (Fig 3 in 1), are mostly lost to consumption by predators (Fig 6 in 1), 2) Males can’t sing until their adult bodies are fully sclerotized, and 3) they need a significant number of males present before they will chorus. That said, chorusing typically begins within two weeks 2. Males will continue to chorus until enough cicadas die to no longer sustain the chorus, which is why the chorus lasts less than a month.

Length of the emergence of an entire brood:

An emergence spanning multiple states could last between 8 to 10 weeks from when the first cicadas emerge in the South to when the last cicada dies in the North. For example, Brood XXIII began appearing the second to last week of April in Mississippi, and there were likely some left in southern Illinois up until the last week of June.


1 Kathy S. Williams, Kimberly G. Smith, and Frederick M. Stephen, Emergence of 13-Yr Periodical Cicadas (Cicadidae: Magicicada): Phenology, Mortality, and Predator Satiation, (1993), Ecology, Volume 74, Issue 4 (Jun., 1993), 1143-1152
2 Kathy S. Williams and Chris Simon, The Ecology, Behavior, and Evolution of Periodical Cicadas, (1995), Annu.Rev. Entomol. 40:269-95

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