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May 7, 2016

Magicicada Media Faux Pas

Filed under: Chris Simon | Magicicada | Periodical — Dan @ 7:38 am

cicada invasion

The media (news papers, bloggers, etc.) sometimes use terms to describe cicadas, and periodical cicada emergences, that range from simply incorrect to grossly hyperbolic. It is unclear if they do this to match reader expectations, to get more clicks, to write a more entertaining article, or simply because they don’t have all the facts. It bothers me when the media uses a photo or video of the wrong species, which is why I have the use the correct image page.

What media mistakes have you witnessed? Let us know in the comments.

Professor Chris Simon, of the University of Connecticut Simon Lab, is one of the premier cicada experts in the world. She provided us with her list of Magicicada Media Faux Pas (below). How many of these have you seen? Can you think of more?

Incorrect Descriptive Words

  • “swarm” They don’t swarm—i.e. fly around in large groups.
  • “invasion” They don’t invade. They have been there the whole time.
  • “plague”
    They are not a plague like grasshoppers that come in and eat everything–they don’t chew leaves. They suck.
  • “overrun” Implies that they are imposing us when in fact we are much more of an imposition on them–clearing their trees and building Walmarts on top of them.

Here are some more funny ones…

  • “lurking underground” They are not lurking or threatening, they are innocently feeding on tree roots.
  • “hatching out of the ground” They don’t hatch out of the ground, they hatched from eggs in tree branches 17years ago.

April 30, 2016

64 Degrees Fahrenheit Eight Inches Deep

Filed under: James Edward Heath | Magicicada | Periodical — Dan @ 1:22 am

hot under the exoskeleton

Soil temperature triggers periodical cicada emergences:

James Edward Heath in his paper Thermal Synchronization of Emergence in Periodical “17-year” Cicadas (Homoptera, Cicadidae, Magicicada)1 discovered that periodical cicadas will emerge, on average, when the soil 8 inches below the ground reaches 64 degrees Fahrenheit:

Soil temperature at 20-cm [7.87 in] depth in seven locations averaged 17.89 C [64.202 F] at the time of emergence, regardless of date. Cicadas emerging from burrows had average body temperatures of 18.04 C [64.472 F]. Synchrony in emergence may be due to animals reaching a critical threshold temperature.

The soil warms their bodies and that triggers the cicadas to emerge.

A warm rain, which will seep into the earth and warm the bodies of cicadas, can trigger a “particularly intensive” emergence.

Alexander and Moore (1962) noted that emergences were particularly intensive following warm rains ( > 2 0 C ? ). I believe this suggests that the soil temperature probably was near emergence temperature and the heat transported by the water percolating into the ground warmed the soil sufficiently to raise soil temperature above the emergence threshold.

Some unanswered questions I have are: 1) how long does the temperature have to be 64°F+ – just a moment, or a certain number of hours, and 2) because we know not all cicadas emerge instantaneously, what is the maximum temperature that for certain will clear them from the soil?

This is an example of a temperature probe use to study the emergence temperature of cicadas. The probe in this picture is held by cicada researcher Gene Kritsky:
Gene Kristsky's Cicada Thermometer

Note that males typically emerge before females and that the larger ‘decim species emerge before the smaller cassini species.

For a more modern, crowd-sourced study of this see the radiolab Cicada Tracker project.

I think I know what you’re thinking: “I don’t own a temperature probe, how can I guess when the temperature is 64°F 8” below the soil? Direct sunlight, air temperature, and rain warms the soil. Southern facing land will warm sooner than northern facing land. Land in direct sunlight will warm faster than land in shade. Rainfall on an 80°+ day will quickly do the trick, but two weeks of temps in the 70°’s should work as well. So keep an eye on the 10-day weather forecast and watch for those days in the 70s, and especially the 80s.

Minimum Flight Temperature:
Their body temperature needs to be a little warmer than that to fly. Their minimum flight temperature (MFT) is 18-21°C / 65-70°F. The temperature varies depending on the Brood and species. They’ll need a few more degrees before they’re fully functional, and start singing and mating.

So, until their bodies are about 72°F (“room temperature”) they won’t be flying, singing and mating.

Maximum voluntary tolerance temperature:
Maximum voluntary tolerance temperature (MVT) for periodical cicadas is 31-34°C / 88-93°F, again depending on Brood and species. Maximum voluntary tolerance is the point at which cicadas seek shade and when thermoregulation takes precedence over other behaviors.

See Thermal responses of periodical cicadas: within and between brood parity (Hemiptera: Cicadidae: Magicicada spp.) and Thermoregulation by Endogenous Heat Production in Two South American Grass Dwelling Cicadas (Homoptera: Cicadidae: Proarna) for more information.

1 Thermal Synchronization of Emergence in Periodical “17-year” Cicadas (Homoptera, Cicadidae, Magicicada) by James Edward Heath, American Midland Naturalist, Vol. 80, No. 2. (Oct., 1968), pp. 440-448.

April 27, 2016

Please use the correct imagery for 17 year cicadas

Filed under: Identify | Magicicada | Periodical | Video — Dan @ 1:01 am

If you’re writing an article about the coming emergence of the 17-year periodical cicadas, please use the correct genus & species of cicadas.

The genus of all 17-year cicadas is Magicicada, and they are never green. The three species of 17-year cicadas are Magicicada septendecim, Magicicada cassini, and Magicicada septendecula. They’re all black with orange wings and legs and red eyes (some exceptions, but they’re never green). The four species of 13-year cicadas are Magicicada neotredecim, Magicicada tredecim, Magicicada tredecassini and Magicicada tredecula (also never green). More information about these species.

An adult Magicicada septendecim by Dan Mozgai/cicadamania.com:

Magicicada septendecim Brood VII 2018 09

An adult Magicicada septendecim by Dan Mozgai/cicadamania.com:

Face of an adult cicada

A newly emerged, teneral, Magicicada septendecim by Dan Mozgai/cicadamania.com:

Teneral Cicada

17-year cicada video:

A singing Magicicada septendecim:

Singing Magicicada septendecim from Cicada Mania on Vimeo.

A Magicicada septendecim laying eggs:

A Magicicada septendecim up close (deceased):

Magicicada on a tree (mostly Magicicada cassini):

For the sake of cicada correctness, feel free to use them in your article. Just credit cicadamania.com.

If you are looking to license Magicicada images or HD Video, Roy Troutman has plenty of both. Reach out to him if interested. His images and video are tagged throughout the site.

Hundreds of shed cicada skins (exuvia) by Troutman:

Click/tap for a larger version:
2014 Ohio Exuvia Pile by Roy Troutman

Wrong Cicadas:

If the cicada you use in your article is green, it isn’t a 17-year cicada. I repeat: if the cicada is green it is not a 17-year cicada.

The cicada at the top of the Wikipedia page for cicadas is not a 17-year cicada, it’s an annual cicada called Neotibicen linnei:

Tibicen linnei
(photo credit for this Neotibicen linnei).

Looking for people to speak at a conference or “cicadacon”?

Need a speaker for a Cicada Convention or a Periodical Cicada Event? Try these folks:

February 7, 2016

The Periodical Cicada Brood VII Revisited

Filed under: Brood VII | Magicicada | Periodical — Dan @ 9:22 pm

The Internet Archive has a lot of cicada documents and information, including a growing collection of articles from journals.

Today I came across a paper about Brood VII called The Periodical Cicada Brood vii Revisited (Homoptera, Cicadidae) by L. L. Pechuman, published in 1985 in the journal Entomology News (link to the article). Brood VII will be back in New York in 2018 (not too far away) so I’m glad I found this now. Brood VII is interesting because it is geographically isolated from other broods, near the Finger Lakes area of New York. This always makes me wonder what happened that led to their isolation (glacial melting, a massive die off of host trees… who knows).

The article is a quick, but melancholy read — unfortunately Brood VII is a small and dwindling brood; it has gone extinct in many areas, and has suffered over-predation by birds in recent emergences. “Populations were just not high enough to support ‘predator satiation'”, according to L. L. Pechuman.

People who witness massive periodical cicada emergences would never think that they were a fragile insect, but they are and papers like this make that fact abundantly clear.

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.

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.


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.

References:

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

June 27, 2015

What is Predator Satiation?

Filed under: FAQs | Magicicada | Periodical — Dan @ 9:24 pm

Why are there so many Magicicada periodical cicadas, and what does it have to do with the survival of their species? One of the answers is: Predator Satiation.

A predator is any animal that would eat a periodical cicada, i.e., birds, raccoons, squirrels, dogs, snakes, etc. Satiation, in the case of cicadas, means to supply predators with enough cicadas to eat until they are wary of eating and thus avoid them completely.

Predator satiation works like this:
1) Periodical cicadas emerge in tremendous numbers.
2) Adult cicadas are often timid, even after having sclerotized.
3) The first cicadas that emerge are eagerly consumed by predators.
4) The predators are so overwhelmed by the bounty of easily eaten cicadas, that they fill themselves to the point of disgust and exhaustion.
5) This gives the remaining cicadas a chance to escape the predators.

The first periodical cicadas are literally “fodder”, in the battle between predators and periodical cicadas, to use a war/video game analogy.

Look at this periodical cicada: it is thinking “hopefully this creature will eat me, so my siblings will live on!”

Magicicada on my finger by Dan from Cicada Mania on Vimeo.

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. Stephen (Ecology, Volume 74, Issue 4 (Jun., 1993), 1143-1152) is worth reading if you are interested in this topic. They found that predation of cicadas peaks during the first few days of the emergence, and doesn’t resume in significant numbers until three weeks later (see figure 6, if you read the paper).

Unfortunately, this strategy could be detrimental to periodical cicadas in areas with dwindling populations, where there isn’t enough of them to satiate the predators completely.

This strategy might also be used by other types of periodical cicadas like the Chremistica ribhoi of India, or cicadas that emerge in large numbers like Callogaeana festiva of south-east Asia.

What are stragglers?

Filed under: Accelerations | FAQs | Periodical | Periodical Stragglers — Dan @ 1:02 pm

Periodical cicadas often emerge in years before or after they are expected to emerge. When periodical cicadas don’t emerge on schedule we call them stragglers, regardless of whether they show up early or late. Typically cicadas with a 17-year lifecycle will emerge 4 years early, and cicadas with a 13-year cycle will emerge 4 years late.

Probability of Straggling chart from Chris Simon
This image indicates the probability of Magicicada straggler emergences. Courtesy of cicada researcher Chris Simon.

People hear the word straggler and assume it means something that lags behind, but that is a laggard. A straggler can mean something that has deviated from an expected date/time or moved away from others of its kind. That said, periodical cicadas that emerge early can also be called precursors, but in the scientific literature, they are called stragglers.

Visit Brood Chart to see when stragglers will be most likely.

Extremely likely stragglers in the next few years:

2020: Brood XIII 4 years early.
2021: Brood XIV 4 years early.
2025: Brood I 4 years early.

Likely stragglers in the next few years:

2020: Brood X 1 year early.
2021: Brood IX 1 year late.
2022: Brood X 1 year late.
2023: Brood XIII 1 year early.
2024: Brood XIV 1 year early.

Accelerations

An acceleration occurs when periodical cicadas straggle in numbers significant enough to sustain future generations. In other words, a large population of a 17-year brood emerge in just 13 years, they avoid being eaten by predators, they mate and reproduce, and then 17 years later their offspring emerge in large enough numbers to reproduce and sustain their population. This is one reason why two different broods might exist in the same area. 1

It is thought that Brood X was formed when a group of Brood XIV accelerated 4 years (they emerged in 13 years, rather than 17). Then Brood VI came from Brood X, and Brood II came from Brood VI. Brood XIV -> X -> VI -> II is called the “main sequence”1.

Accelerations may have been more prevalent and successful (successful in terms of sustaining future generations) in the past when much of eastern North America was forests, and there was no human intervention or destruction of habitat to interfere.

References

1 Monte Lloyd & Jo Ann White. Sympatry of Periodical Cicada Broods and the Hypothetical Four-Year Acceleration. Evolution, Vol. 30, No. 4. (Dec., 1976), p. 795.

Here’s a paper that discusses 13-year Magicicada emerging 4 years early: David C. Marshall, Kathy B. R. Hill, and John R. Cooley “Multimodal Life-Cycle Variation in 13- and 17-Year Periodical Cicadas (Hemiptera: Cicadidae: Magicicada),” Journal of the Kansas Entomological Society 90(3), 211-226, (1 July 2017). https://doi.org/10.2317/0022-8567-90.3.211

June 11, 2015

Look and listen for Magicicada stragglers in 2015

Filed under: Brood V | Brood VIII | Magicicada | Matt Berger | Periodical | Periodical Stragglers — Dan @ 1:01 am

Another straggler sighting, this time in Cleveland which should make it a Brood V one year straggler:

Matt Berger Brood V Stragger 2
A Brood V straggler found by Matt Berger in West Virginia. See more photos of this cicada.

The emergence of Brood XXIII is well underway in the states along the Mississippi, and Brood IV should kick off in the west as soon as it stops raining every day. These aren’t the only Magicicada periodical cicadas emerging in the U.S. this year — some stragglers will emerge as well.

A straggler is a periodical cicada that emerges before or after the rest of its brood. Typically a straggler belonging to a 17 year brood will emerge 4 years early, but they might also emerge a year early, or a year late, or even 4 years late. This probability chart, details the probability of a straggler emergence.

In 2015 you might find the following stragglers:

Tyla MacAllister found a Brood XIX Magicicada straggler (emerged 4 years late) in Alabama!

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