Category: Genera

Genera of cicadas.

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Magicicada Periodical

Reading a 97 year old cicada news article

Locust

I was looking through old newspapers for articles about periodical cicadas. I found an article in the Taiban Valley News from April of 1919, titled “17-Year Locust” Due This Year1. The Taiban Valley news was published out of New Mexico, which does not experience periodical cicadas aka “17-year locusts”, so I guess the story was supplied to its readers as a curiosity — just something oddball/interesting to read. The text of the article was supplied by the U.S. Department of Agriculture (possibly C.L. Marlatt himself), and the main image of the article is an illustration that appeared previously in U.S. Department of Agriculture documents and is attributable to a Miss L. Sullivan2.

“Locusts”

97 years ago people called periodical cicadas “locusts”, just as they do today. I quote, “It has been so long miscalled by the name of locust, however, that there is no hope of divesting it of that incorrect appellation”. “No hope”! Even today, about half the people I meet call them “locusts”.

Human lifespans were a lot shorter 97 years ago

The next fact — and this startled me — is how short the average human lifespan was 97 years ago. I quote: “The fact that it appears in countless numbers one year, then is not seen again for half the average lifetime of human beings and then suddenly appears again in countless numbers”.

Half the average lifespan of human beings? Back in 1919 the average life expectancy was just 55. At most a person could expect to witness 3 emergences back then, and since babies and toddlers really don’t remember things, 2 times makes sense. Today (2016) life expectancy is around 79 years in the U.S., which means the average person will only get to see 4. I’ve seen 9, but I travel around.

Vermont still had periodical cicadas:

Back in 1919, Vermont still had periodical cicadas: “with some Isolated colonies as far northeast as upper Vermont”. Since then, they must have gone extinct.

Brood 18?

The article talks about Brood 18 emerging in the same year as Brood 10 (note, the article does not use Roman numerals). I believe the Brood 18 the article they refer to is what we now call Brood 19 (XIX) today. The article describes Brood 18 as having a 13-year life cycle, and occurring in Alabama, Georgia, North Carolina, South Carolina and Tennessee. The only brood that matches that is Brood XIX (see the map).

If it is indeed Brood XIX, the article is likely incorrect about the coincidence of Brood XIX and X emerging in 1919. While Brood X definitely emerged in 1919, Brood XIX would emerge in the following year 2020. Interestingly enough, the now extinct Brood XI emerged in 2020 (in Connecticut).

The rest of the article is less remarkable, but still a fun read for “the most interesting insect in the world”.

Update (8/26/2016):

David Marshall of the University of Connecticut pointed out a map of the Brood XVIII that was indeed set for emergence in 1919, which is likely what the writes of the article were citing. David points out though that this Brood XVIII was likely comprised of one-year-early emergences (stragglers) of Brood XIX, rather than an actual unique brood.

Brood XVIII

The periodical cicada, Marlatt, C. L., Washington, D.C. :U.S. Dept. of Agriculture, Bureau of Entomology,1907.

1 Taiban Valley news., Taiban, Roosevelt County, N.M. April 04, 1919.
2 C. L. MARLATT. Account Of Cicada Septendecim, Its Natural Enemies And The Means Of Preventing Its Injury, Together With A Summary Of The Distribution Of The Different Broods. U. S. Department Of Agriculture. Division Of Entomology. Bulletin No. 14. 1898.

Categories
Citizen Science Flagging Magicicada Ovipositing Periodical

Got Flagging? Report flagging and egg nests.

Got flagging? Flagging happens when tree branches wilt or die due to cicada egg laying, resulting in bunches of brown leaves. Don’t worry, this will not cause trees to die, unless they are small and weak trees. Flagging can actually do a tree a favor, by removing its weakest branches.

Some video of cicada flagging:

A photo of flagging:

Periodical Cicada Flagging

Categories
Brood V John Cooley Magicicada Matt Berger Periodical

My 2016 Brood V Experience

Magicicada exuvia on an oak leaf_sm
Many exuvia clinging to oak leaves. Core Arboretum, WVU.

My plan was to check out Maryland first, then head to West Virginia for a few days, and then Ohio. If weather, time and patience allowed, Virginia and Long Island, New York. Like all my periodical cicada trips I start by consulting the map on Cicadas @ UCONN (formerly Magicicada.org) to see where folks are finding cicadas. I also consult with the folks who study periodical cicadas professionally to discover their favorite hot spots and any locations of particular scientific interest. This year, the interesting spot was north-western Maryland — more on that later.

Generally speaking, you’ll see a lot of pin-drops for Magicicada cassini on the map. This is because you can hear them while driving at 70mph. You often have to stop your car and turn off the engine to hear the other species, so even though there’s lots of M. cassini on the map, there’s probably just as much M. septendecim. Generally speaking, my mapping methodology works like this: I stop and take notes when I can (usually at rest stops, parks or when I’m staying in a particular town — see Morgantown & Athens later in the article) and this is when I’ll hear M. septendecim & M. septendecula, but when I’m driving interstate highways at high speeds (with a parade of angry drivers who would rather tailgate me that use the left lane to go around me) I can only take data points for M. cassini.

What do I bring with me on a seven-day cicada road trip? Aside from clothes, road food, smartphone, and my AAA card, I bring equipment to aide my study of cicadas:

  • A junk computer. A decrepit laptop that I won’t care if it gets stolen.
  • A video camera.
  • A device for measuring sound level (decibels).
  • A notepad and pen (because technology fails).
  • Butterfly pavilions, which are these expandable enclosures for holding and observing insects.
  • Containers for holding dead specimens, and silica gel to keep them dry. Note: before you collect, make sure it is legal in the location you plan to collect. Collecting wildlife from National Parks is illegal. Collecting cicadas from a Hampton Inn parking lot is usually okay.
  • Suntan lotion and Bug Spray. I like insects, but ticks and mosquitos can turn cicada observation into a nightmare. Many researchers wear pyrethrum treated clothes (yes, bad for cats).
  • A flashlight.
  • Cicada Mania pins for folks I meet along the way.

What I don’t bring but should is one of John Cooley’s Cicada O Matic GPS Dataloggers. I have to make observations by hand.

Other than that, I follow the typical Power Vacation rules.

Maryland Part 1:

The first town I hit was Accident, Maryland (great name). There were sightings on the Cicadas @ UCONN map, and the name of the town was awesome, so I wanted to check it out. Unfortunately, I didn’t observe any cicadas there.

Route 68, West Virginia

Traveling west along Route 68, about half-way between the center of Bruceton Mills and Coopers Rock State Forest I started to hear pockets of M. cassini. I stopped at Coopers Rock, and at first, I was disappointed: I didn’t hear any cicadas from my car. Once I stopped my car and turned off the engine I could hear them: M. septendecim with their spooky sci-fi UFO chorus in the distance. It became obvious that the park had a healthy population of M. septendecim, with a smattering of M. cassini as well.

Morgantown, WV

Next, I arrived at Morgantown, WV. Some twitter friends had been posting cicada photos from there, so I thought it would be a good location to set up base and make observations for a few days. The hotel I chose had an excellent population of M. septedecim and cassini around it; so much so that the staff couldn’t keep up with unwanted cicada guests that littered their doorway, trampled by oblivious human guests.

My first day there I walked around the West Virginia University campus near the hospital, stadium & iHop. The sky was overcast and it was getting late in the afternoon, but it was clear that the campus and town had an abundance of periodical cicadas, and that I made a good choice in setting up camp there. At night, in my hotel parking lot, I was able to watch cicadas emerge as nymphs as transform into adults, which is always a highlight of an emergence for me.

WVU Core Arboretum

Core Arboretum is a large botanical garden devoted to trees (“arbor”) on the WVU campus. It was an excellent place to observe cicadas. I was able to observe all three species, the tiny but LOUD M. cassini, the larger & relatively docile M. septendecim, and the rarest of the species M. septendecula. Finding M. septendecula so early in my trip was a treat. Their clockwork/tambourine sound (at least that’s what I think they sound like) gave them away.

I met entomologists Matt Berger, who has contributed many cicada photos to this site over the years, and his colleague HereBeSpiders11 (twitter name). Awesome people. I met Zachariah Fowler, the director of the arboretum as well. Another awesome person.

Magicicada white eyes
A white-eyed Magicicada septendecim.

I was able to check off many of my cicada checklist items in Morgantown: I found a white-eyed cicada, I saw & heard all three species, and more.

Leaving West Virginia, Entering Ohio

M. cassini were plentiful along route 79 and 50 headed west towards Athens, Ohio. Along the way, I made a few stops and heard & observed some M. septendecim as well.

Athens, Ohio

Athens was another good location to stay and observe cicadas. The parks in the surrounding area had excellent cicada populations, and I had a rare chance to meet John Cooley of Cicadas @ UCONN (formerly Magicicada.org).

My first day in Athens I spent at Dow Lake in Strouds Run State Park. There I met John Cooley who was there showing a German film crew the particulars of cicada behavior. Dow Lake had a healthy mix of LOUD M. cassini and M. septendecim, but the cassini definitely dominated. The highlight for me was not a cicada, but spotting a rat snake climbing down from an acacia tree where it was no-doubt snacking on cicadas.

Sells Park in Athens was a nice place to hear VERY LOUD M. cassini choruses, well into the high 80-90db mark. So loud that I limited my time there, and left after an hour.

Hocking Hills

Hocking Hills is an amazing park north of Athens than features a spectacular above-ground cave and many acres of forest filled with cicadas. Hocking Hills had a good population of all three species, and M. septendecula were unusually easy to find. They seem to have preferred areas where deciduous trees blended with evergreens, at least in the locations I found.

Vinton Furnace Experimental Forest

A Magicicada cassini chorus from the Experimental Forest:

A Magicicada chorus with audible M. septendecula from the Experimental Forest:

Vinton Furnace Experimental Forest is a forest curated to include as much biological diversity as possible. All three periodical cicada species make up part of that diversity. M. septendcula choruses were very easy to find. The forest was thrilling to visit — aside from the biting deer flies, it was exhilarating to see or hear so many species of insects, birds, and plants in one place. Also, thrilling were the winding one-lane dirt roads; I almost died a few times thanks to wild drivers out for a pretend Finland Rally race.

Back to Maryland

After an overnight stop back in Morgantown, WV, I headed back to Maryland to prove (or disprove) that periodical cicadas were there, and if I did find them, the extent of their population. It is important to show the limits of their population as researchers (John Cooley in particular) are interested in demonstrating that the Brood V population in Ohio, Pennsylvania, West Virginia & Maryland is distinct from the population in Virginia.

I’m happy to report that I did find periodical cicadas in Maryland. The populations were mostly the relatively quieter M. septendecim — the type you really have to stop the car & turn off the engine to be certain they’re there. I did find M. cassini as well, but M. septendecim dominated. The adorably named Friendsville and Selbysport had good populations, as did the hill above the Youghiogheny river overlook rest stop on I68. South of this area, I did not hear or see cicadas on Bear Creek Road, Rt 42, Rt 219 or Rt 495. It is possible there are pockets of cicadas deep in the woods and out of earshot in those areas, but it is clear there was no great population of periodical cicadas in those areas if any at all. I spoke to a chainsaw bear sculptor in Bittinger, which is not far from where the Appalachian Plateau ends & the Ridge and Valley area starts. I showed him a photo of a periodical cicada. He said he had never seen them in his life, and nor did he see them in Accident where he went to church. He did hear about them on the news, so he was aware of them.

Maryland

Pennsylvania, and home

After collecting cicada data and buying a chainsaw bear, I headed north into Pennsylvania. I stopped at a rest stop, enjoyed the last I would hear of Brood V, and headed back home.

More!

Categories
Brood V Magicicada Periodical

Jim Thorpe Pennsylvania Magicicada Emergence

There was an unexpected* emergence of periodical cicadas in Jim Thorpe, Pennsylvania this spring. Experts believe it is a disjunct brood related to Brood XIV. Brood XIV is found in the area, according to entomologist and Pennsylvania-based periodical cicada mapper Marten Edwards, but perhaps not in the exact same specific locations. Brood II is also in the area but on the other side of the mountain. Although this group of cicadas emerged the same year as Brood V, it probably is not related (genetically & evolutionary), but that is TBD.

The terrain of the Jim Thorpe area is comprised of mountains & valleys belonging to the Appalachian Mountain system of the Eastern United States. I observed cicadas on mountainsides and in lower valley areas. They seemed most plentiful and gregarious on the edges of the forest, preferring small, young maple trees where they gathered, sang, paired off, mated and died. Although their numbers were lesser deep in the woods, I did find exit holes and exuvia there. The most interesting discovery was finding a fully sclerotized, but dead, adult cicada within an overturned teacup left in the shade of an old tree. I discovered a few “cicada chimneys”, vertical structures made of soil surrounding exit holes, under pine trees where the cicadas seemed to need to extra hight to get above the thick layer of pine needles that littered the forest floor.

The best populations seemed to be along the Lehigh Gorge Trail from its entrance on Main Street to the Lehigh Gorge, and north, up the mountain the Lehigh Gorge Trail circumscribes, all the way to Lehigh Gorge Drive. The trees along Route 903, starting at Old Pipeline Road and heading south, were loaded with active cicadas — so many, that it was hard to avoid their flying bodies as I drove towards downtown Jim Thorpe.

If you want to see them, go this weekend (June 24-26). They were plentiful in the Lehigh Gorge area:
Lehigh Gorge

The population seems to be entirely made up of Magicicada septendecim. No Magicicada cassini or septendecula were found (so far).

A Carolina Grasshopper (Dissosteira carolina) next to a “Locust” (Magicicada septendecim).
Grasshopper and Cicada
More photos from this emergence in the gallery.

Locals were calling them “Locusts” — sometimes I forget that’s what folks call them, but of course they’re really cicadas.

Sound files: all are Magicicada septendecim

A single call:

A Spectrogram of its call:

Magicicada septedecim spectrogram

Multiple males calling:

An extra-weird call around 11-12 seconds:

You can here some wing flicks in this one:

*Unexpected as cicada researchers were not expecting it, but locals probably knew about it.

Post script:

I found a scan of a news paper from 1880 (The Carbon advocate., March 06, 1880, Lehighton, Pa.) that mentions that “locusts” would emerge in the area in the summer. “Locust” is, of course, a common misnomer for cicada, the Carbon Advocate was the paper for the Mauch Chunk (Jim Thorpe) area, and 1880 was 8 x 17 years ago:

News Clipping

Categories
Brood V Magicicada Matt Berger Periodical Video

Periodical cicada photos and video from Brood V

I took a lot of cicada photos and video when I traveled to Maryland, West Virginia and Ohio. Matt Berger also contributed a gallery of cicada photos to the site.

Some of my photos:

Red and Orange eyes; Brood V

Magicicada exuvia on an oak leaf_sm

Magicicada white eyes

Photos of the Brood V emergence by Matt Berger.

A sample of Matt’s photos. Click/tab for larger versions:

A Variety of Eye Colors by Matt Berger
A Variety of Eye Colors by Matt Berger. Brood V.
Gray Eyed Cicada Up Close by Matt Berger
Gray Eyed Cicada Up Close by Matt Berger. Brood V.

Molting Cicadas:

Magicicada with White Eyes:

More videos.

Categories
Brood V Magicicada Periodical

Brood V 17-Year Cicadas Due in Spring of 2016

Brood V will next emerge in 2033.

This page was last updated in 2016.

Brood VBrood V (5) 17-year cicadas have emerged, this spring of 2016, in Maryland, New York, Ohio, Pennsylvania, Virginia & West Virginia.

Latest Updates:
(7/4/16): It’s a wrap! I’m sure there are some periodical cicadas hanging on out there, but for the most part, the emergence should be over. I hope you had fun.

(6/26/16): By now you should see (and hear) sharp declines in cicada populations. They’ll be gone in most places by July 4th. You should start to see Flagging of tree limbs where the cicadas lay their eggs. This is a natural part of the process.

New: Use our checklist to keep track of your Brood V experience!

Gene Kritsky has updated his book “In Your Backyard: Periodical Cicadas“. It is available for the low price of $4.99 for Kindle and Kindle readers. Totally worth it.

About Brood V:

The cicada species that will emerge are Magicicada cassinii (Fisher, 1852), Magicicada septendecim (Linnaeus, 1758), and Magicicada septendecula Alexander and Moore, 1962. These periodical cicadas have a 17-year life cycle. The last time they emerged was 1999.

When: Generally speaking, these cicadas will begin to emerge when the soil 8″ beneath the ground reaches 64 degrees Fahrenheit. A nice, warm rain will often trigger an emergence. So, definitely May, but something might happen in April if we have a particularly hot spring.

Locations where they are likely to emerge:

This data comes from the Cicada Central Magicicada Database (RIP) and other sources.

Although the cicadas will emerge in MD, NY, OH, PA, VA, and WV, the area is limited and patchy. No Brood V cicadas for D.C., Cincinnati, or NYC (people have asked). Their range is closer to this map (with cicadas in the orange areas):

Brood V range

Maryland:

Counties: Garrett.

New York:

Specific locations in L.I.:

  • Wildwood State Park – Confirmed!

Counties: Suffolk (Long Island).

Ohio:

Specific locations in Ohio:

  • The emergence should be good in the south eastern part of the state and in Summit, Medina, and southern Cuyahoga counties1.
  • Hocking State Forest, Hocking county, which is where James Edward Heath performed his investigation of periodical cicada Thermal Synchronization2.
  • Tar Hollow State Forest, in Laurelville, Hocking County, Ohio.
  • Strouds Run State Park, in Canaan Township, Athens County.
  • Athens, Athens County, Ohio
  • Findley State Park, Lorain County, Ohio.

Counties: Ashland, Ashtabula, Athens, Belmont, Carroll, Columbiana, Coshocton, Crawford, Cuyahoga, Fairfield, Franklin, Gallia, Geauga, Guernsey, Harrison, Hocking, Holmes, Jackson, Jefferson, Knox, Lake, Lawrence, Licking, Lorain, Mahoning, Medina, Meigs, Muskingum, Noble, Ottawa, Perry, Pickaway, Pike, Portage, Richland, Ross, Sandusky, Scioto, Seneca, Stark, Summit, Trumbull, Tuscarawas, Vinton, Washington, Wayne

Thanks to Roy Troutman, John Cooley, Chris Simon and Gene Kritsky for the tips!

Pennsylvania:

Counties: Allegheny, Fayette, Greene, Somerset, Washington, Westmoreland

Virginia:

Specific locations in Virginia:

  • Douthat State Park, in Bath & Allegheny County Virginia.

Counties: Allegheny, Augusta, Bath, Highland, Richmond, Rockingham, Shenandoah

West Virginia:

Counties: Barbour, Boone, Braxton, Brooke, Cabell, Calhoun, Clay, Doddridge, Fayette, Gilmer, Grant, Greenbrier, Hampshire, Hancock, Hardy, Harrison, Jackson, Kanawha, Lewis, Marion, Marshall, Mason, Monongalia, Nicholas, Ohio, Pendleton, Pocahontas, Preston, Putnam, Raleigh, Randolph, Ritchie, Roane, Taylor, Tyler, Upshur, Webster, Wetzel, Wirt, Wood

Learn more about Brood V:

For historical purposes, Here’s C. L. Marlatt’s map from 1914:

Marlatt, C.L.. 1914. The periodical cicada in 1914. United States. Bureau of Entomology. Brood Map for Brood V.
Marlatt, C.L.. 1914. The periodical cicada in 1914. United States. Bureau of Entomology

1 Kritsky, G., J. Smith, and N. T. Gallagher. 1999. The 1999 emergence of the periodical cicada in Ohio (Homoptera: Cicadidae: Magicicada spp. Brood V). Ohio Biological Survey Notes 2:43-47.

2 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.

* The map is based on this map from the Wikimedia Commons by Lokal_Profil.

Categories
Anatomy Magicicada Video

The anatomy of a freshly molted cicada

This video points some of the anatomical features of a freshly molted Magicicada, like it’s tarsal claws, rostrum, clypeus, stylets, and spiracles.

The video was made with Camtasia and Pixelmator — nothing fancy; just a quick video for people experiencing molting cicadas for the first time.

Categories
Magicicada Periodical Stragglers

Cicada Straggler Alert 2016

Straggler Alert

The point of this article is that you should be on the alert for Magicicada periodical cicadas, no matter what year it is, and if you see or hear them, report them.

Stragglers, in terms of cicadas, are periodical cicadas that emerge in years prior to (precursors) or after their brood is expected to emerge. Most often, 17 year cicada stragglers emerge four years prior to their expected emergence date — but it is possible for periodical cicadas to emerge between 8 years earlier and 4 years later than expected. Read more about cicada stragglers.

This year (2016) Brood IX stragglers should emerge in southern West Virginia, western Virginia and the north-middle part of North Carolina that connects with western Virginia. See a map here.

Looking at the live map on Cicadas @ UCONN (formerly Magicicada.org), it is obvious that most reports come from Brood V and stragglers appear to be emerging in the Brood IX & VI areas as expected — however, there are a fair number of reports in the Brood II and X areas, which is odd.

Map

  • Red: Brood V
  • Orange: Brood IX, 4 years early (most probable)
  • Yellow: Brood VI, 1 year early (probable)
  • Green: Brood II, 3 years late (rare, but possible)
  • Dark Green: Brood X, 5 years early (rare, but possible)

As stated before, it is common for periodical cicadas to emerge 4 years early, but 5 years early is rare. So why Brood X be stragglers this year? That requires a little more thought.

Now we enter the realm of conjecture…

Rick Karban in the paper How 17-year cicadas keep track of time1 demonstrated how you can get cicadas to emerge earlier than expected if you alter the seasonal cycles of their host trees. Make the tree experience two cycles in one year, the cicadas will read this as “two years have passed” and they’ll emerge a year earlier. So, in the case of Brood X stragglers, it could be that their host trees experienced weather fluctuations that caused them to do something that signaled the cicadas that 2 years had passed. Add the 4 years they would likely straggle + 1 year caused by fluctuations from the host tree, and that makes for a 5 year straggler.

The other day wethertrends360 posted this on their facebook page:

Growing Degree Days tell us why the Northeast had such an early surge in plant growth but then slowed. From late February to early April temperatures were near record warm in the Northeast with the 2nd most Growing Degree Days (GDD) in 25 years (chart/map left). This allowed plants to emerge way too early and then the freezes came!

Perhaps this early surge in plant growth, then a freeze, then growth again seemed like two years had passed to some cicadas. Perhaps.

1 How 17-year cicadas keep track of time, Richard Karban, Carrie A. Black1 and Steven A. Weinbaum, Ecology Letters (2000) 3 : 253-256.

Categories
Chris Simon Magicicada Periodical

Magicicada Media Faux Pas

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.
Categories
James Edward Heath Magicicada Periodical

64 Degrees Fahrenheit Eight Inches Deep

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.