Auf wiedersehen Brood X: Cicadas, Magicicada spp.

Over the last three months, we explored the ecology, behavior, and interactions of Brood X periodical cicadas with humans, other animals, and plants in the eastern United States.  We visited cicadas underground, watched the emergence of cicada nymphs from their subterranean crypts, discovered how male cicadas make noisy and ethereal sounds, learned how to tell the boys from the girls, watched as hungry predators enjoyed the cicada bounty, witnessed mating and oviposition by females, shuddered at their lethal STD, and witnessed havoc wrought upon young trees when females laid their eggs. In the waning weeks of June here in the DMV at locations that had formerly been zones of rollicking cicada choruses a few weeks ago, there is now an eerie silence. The reason for the hush is immediately apparent. Beneath trees and shrubs, the ground is littered with thousands of spent exuviae, the shed skins of cicada nymphs, and the bodies of adult cicadas that survived the onslaught of hungry sparrows, blue jays, hawks, mocking birds, foxes, raccoons, squirrels, dogs, and dozens of other predators. Also scattered about are wings and fragmented body parts of cicadas that were not so lucky. Macabre half cicadas with abdomens transformed into fungal fruiting bodies litter the ground, victims of Massaspora. Hungry ants and maggots repurpose cicada protein and return it to the food web. Along neighborhood roadways and sidewalks greasy black patches mark the spots where cicadas found their final resting place beneath the tires of vehicles or shoes of humans.

What other legacies did cicadas leave behind? For the natural world they provided a bounty for countless predators. This year, birds produced larger clutches more frequently and nestlings were heavier and enjoyed greater survival (Anderson 1977, Strehl and White 1986). As cicadas return to the earth upon death, decomposition of their remains creates a pulse of nutrients to the forest floor boosting microbial biomass, adding nutrients, and enhancing the growth and reproduction of understory plants (Yang 2004). Similar changes in microbial communities occur when cicadas enter streams (Menninger et al. 2008). Young trees took a beating when female cicadas laid eggs in small branches but trees protected by cicada netting were largely spared from this injury (Ahern et al. 2005). Although established mature trees experienced cicada injury, they are able to shrug off this insult in the long run (Clay et al. 2009).

As the door closes on Brood X in 2021, cicadas leave behind billions of holes to aerate the soil, a feast for necrophagous creatures like tiny hungry ants, oily spots along roads where cars were the grim reaper, sidewalks littered with shells and carcasses, and tons of shed skins and decaying bodies that return nutrients to the soil. A solitary late comer to the party wanders amongst earthly remains of its brood mates.  Auf wiedersehen Brood X, until next time in 2038.

For cicadaphiles, this was a season to enjoy a truly remarkable event that happens nowhere else on earth except in the eastern Unites States, only a handful of times in a lifetime. Cicada lovers from as far away as California planned family vacations to enjoy the emergence of Brood X while cicadaphobes tried to cope with the immensity of the event in various ways. Some strove to understand cicadas better and were counseled on how to cope with these red-eyed critters, while others planned a cicada escape. One friend had plane tickets at the ready and when warned that emergence was just around the corner, he departed for a cicada escape to Idaho. For Bug of the Week, it was a welcome break from COVID and other strange events of the past year and a fine time to share a few bug stories. Here in the DMV cicadas had a spectacular run and the teenage offspring of Brood X, 2021 will return in 2038 for their day in the sun.

Acknowledgements

Bug of the Week thanks members of the Cicada Crew, journalists of print and non-print media, neighbors of the Allview community in Columbia, MD, and cicada geniuses that devote their professional careers to studying these strange, whacky, and mysterious insects, who all assisted in the telling of cicada stories. The following references were used to prepare this episode: “Reproductive responses of sparrows to a superabundant food supply” by T. R. Anderson, “Effects of superabundant food on breeding success and behavior of the red-winged blackbird” by C. E. Strehl and J. White, “Periodical cicadas as resource pulses in North American forests” by L. H. Yang, “Periodical cicada detritus impacts stream ecosystem metabolism” by Holly L. Menninger, Margaret A. Palmer, Laura S. Craig, and David C. Richardson,“Effects of oviposition by periodical cicadas on tree growth” by Keith Clay, Angela L. Shelton, and Chuck Winkle, and “Comparison of exclusion and imidacloprid for reduction of oviposition damage to young trees by periodical cicadas (Hemiptera: Cicadidae)” by R. G. Ahern, S. D. Frank and M. J. Raupp.

This post appeared first on Bug of the Week

With thousands of cicadas chorusing in the treetops this week, male cicadas wooed potential mates and females chose the fathers of their offspring. Within hours of mating, females move to the tips of branches and select soft greenwood terminals about the diameter of a pencil to be the nursery for their offspring. Using a sharp egg-laying appendage called an ovipositor, the female cicada slices narrow slits parallel to the long axis of the branch. She then inserts her hollow ovipositor into the branch and with powerful abdominal contractions, she pumps between 20 and 30 tiny eggs into each slit, creating what is technically known in cicada-speak as an egg nest. Each female has the potential to lay between 200 and 400 eggs during the course of her two to four-week lifespan. In the warmth of summer days and nights, cicada eggs develop and, after six to ten weeks, nymphs hatch and tumble to the earth below.

And now for the dark side of periodical cicadas – plant injury. Injury caused by adults as they sip xylem fluid is inconsequential. The real insult to woody plants comes from the wounds caused by female cicadas when they slice branches to insert eggs. Where densities are great, egg-laying, a.k.a. oviposition, causes tips of many branches to wither and die. Dying and dead terminals droop, resulting in a type of tree injury called flagging. Some injured terminals break and fall to the ground. Branches that do not break may eventually heal, but the wound-site may form a gnarly irregular swelling on the branch.

With the mating game completed, female cicadas fly to small branches where they deposit eggs in egg nests. Using her sharp egg laying appendage called an ovipositor, the cicada slices the branch and then deposits 20 to 30 eggs into each slit to form egg nests.

Which plants are most likely to be affected? The bad news here is that periodical cicadas are broad generalists. Miller and Crowley (1998) studied 140 genera of trees at the Morton Arboretum and found more than half sustained injury caused by ovipositing females.  Among the most severely affected were ones common to landscapes in the DMV, including Acer (maple), Amelanchier (shadbush), Carpinus (hornbeam), Castanea (chestnut), Cercidphyllum (katsura), Cercis (redbud), Chionanthus (fringe tree), Fagus (beech), Quercus (oak), Myrica (bayberry), Ostrya (hophornbeam), Prunus (cherry) and Weigela (weigela). Another study by Brown and Zuefle (2009) of 42 woody plant species added several new genera to the list and found all but 10 species were used by cicadas to lay eggs. This study found that native and non-native woody plants were equally likely to be used for oviposition by cicadas but alien plants, those with no other known congener (plants of the same genus) in the US, were less likely to be hosts for eggs.  

Dense populations of cicadas spell trouble for young trees. Scores of egg nests damage tender branches causing them to wilt, die, and eventually drop from the tree. Withered branches should be carefully pruned from the tree to promote wound closure and encourage restorative growth from axillary buds.

Factors beyond taxonomic identity of a plant affect decisions made by female cicadas regarding where to place their eggs. Small, compact plants often have fewer egg-nests compared to those with longer more open branching habits. Trees at the edges of forests with rapidly growing branches exposed to sunlight often sustain more cicada injury. These trends are easily seen in tree nursery stock and recently transplanted saplings found in yards, commercial landscapes, parks, and transportation corridors, especially those near established trees that historically support cicadas. While ovipositional injury poses a threat to newly planted trees, for older and well-established trees flagging and limb breakage may occur in the short term, however, studies indicate that the long-term threat to tree vitality is minimal (Miller and Croft 1998). Early successional trees exhibited no clear reduction in radial growth or overall growth rates of trees attacked by cicadas (Clay et al. 2009). For small trees and shrubs injured by cicadas, wait until the cicada season ends and remove the injured branches by carefully pruning them back to the nearest node before the cicada injury.

Acknowledgements

Much of the background information for this episode was taken from “Return of periodical cicadas in 2021: Biology, Plant Injury and Management” by Michael Raupp. Other great references include “Does the periodical cicada, Magicicada septendecim, prefer to oviposit on native or exotic plant species?” by W. P. Brown and M. E. Zueffle, “Effects of oviposition by periodical cicadas on tree growth” by K. Clay, A. L. Shelton and C. Winkle, “Periodical Cicada (Magicicada cassini) Oviposition Damage: Visually Impressive yet Dynamically Irrelevant” by W. M. Cook and R. D. Holt, “Effects of periodical cicada ovipositional injury on woody plants” by F. Miller and W. Crowley, and “The ecology, behavior and evolution of periodical cicadas” by K. S. Williams and C. Simon. We thank Randy and all the good folks in the Allview neighborhood for allowing us to visit, photograph, and film cicadas in their landscapes.

This post appeared first on Bug of the Week

This article appeared first on Catseye Pest

This week cicadas have taken to wing, dashing across yards, roadways, and landscapes as they try to hook up with other members of their species. While standing beneath a raucous chorus of Magicicada cassini, a gentle sprinkle wafted down on my head, kind of a summer shower on a hot day provided by the periodical cicadas. Thinking back to John Fogerty’s 1970 lyrical query “I wanna know, have you ever seen the rain, comin’ down on a sunny day”, I mused about what exactly was behind a cicada shower? Recall that cicada nymphs feed on a nutrient poor fluid carried in a vascular tissue called xylem. Developing nymphs process large amounts of this liquid to gain sufficient nutrients to grow. Now consider the needs of the adult cicada. While living a normal life span of two to four weeks, they must mature, find mates, defy death from the jaws of predators, and, for the females, fly to trees to find suitable locations to deposit several hundred eggs. These activities are conducted in sometimes scorching heat that can exceed 90 degrees Fahrenheit. Clearly, cicada adults need some sort of fuel to undertake all these activities in just a few short weeks.

With almost all cicadas up and out of the ground, noisy cicadas are busy flying throughout the landscape to find their brood mates. Hundreds line the trunks and branches of trees to feed and find mates. First at full speed and again at half speed, watch as one female rids herself of liquid waste – a.k.a. cicada pee. Our periodical cicadas produce a gentle shower of pee, but large cicadas of the Costa Rican rainforest can deliver a firehose-like torrent of pee.

Some common lore has it that adult cicadas do not feed; however, adults do indeed feed. Soda-straw-like mouthparts are inserted into the plant’s xylem vessels and a massive pump in the head of the cicada creates negative pressure to suck xylem fluid from vessels located in tree branches and along the trunk, into the digestive tract of the cicada. Xylem fluid replaces moisture lost from these small creatures as they respire and move about. To survive above ground they process vast quantities of fluid. Their specialized digestive tract enables them to suck copious amounts of sap from trees and then rapidly excrete the excess fluid. “Pee” is a term usually applied to urine, a liquid produced by the kidneys of vertebrates to rid the body of metabolic waste products. Cicadas and other members of the Hemiptera clan produce liquid waste. Specialized organs called the malpighian tubules remove waste products from the hemolymph of the cicada and pass it to the colon for excretion. Sucking insects such as aphids and soft scales feed on another vascular fluid called phloem and produce a waste product called honeydew. This sugar-rich liquid is quite different from that produced by cicadas and other xylem feeders. For periodical cicadas, their liquid waste is not exactly “pee”. However, amidst the Brood X cicada chorus, don’t be surprised if you see and feel rain comin’ down on a sunny day.  

Acknowledgements

Bug of the Week thanks Dr. Shrewsbury for inspiring this episode and Randy, ruler of all cicadas, for allowing us to photograph and record cicadas in her beautiful landscape. 

This post appeared first on Bug of the Week

In a previous episode, we described the bizarre strategy called predator satiation used by periodical cicadas to overwhelm hordes of hungry predators intent on filling their bellies with these nutritious insects. The cicada’s long life span may also enable periodical cicadas to elude short-lived predators such as birds and small mammals that simply track cicadas through time. Who can wait 13 or 17 years for their next meal? But one patient nemesis of periodical cicadas has evolved a diabolical plan for making the most of the cicada bounty. In the soil beneath trees where cicada nymphs spend their youth sipping sap, resting spores of the fungal pathogen Massospora cicadina lay in wait for 13 or 17 years. During April and May as cicada nymphs escape from the earth, spores of Massospora adhere to the exoskeletons of nymphs. Compounds on the surface of the cicada send a signal to the spores that dinner is served and it is time to germinate. Like an invading army, the fungus penetrates the skin of the cicada and multiplies, turning the cicada into a fungus garden. In a short suspense, the infection turns the abdomen of the cicada into a buff-colored mass of fungus. At this stage of their life cycle, tens of thousands of newly molted adult cicadas populate the landscape to begin the courtship rituals. The infection sterilizes both male and female cicadas, but does nothing to quell the libido of the sex-crazed male cicada. Infected males continue to seek and attempt to mate with females despite their contagious infection. In a game of tit for tat, female cicadas infected with Massospora remain attractive to healthy males that soon become infected as they attempt to mate with females. At this point in time Massospora becomes a cicada STD and is transmitted from one cicada to another, thereby increasing its numbers each day. While the STD is strange enough, Massospora has one more trick to ensure maximum transmission of its spores. Recall from last week’s episode, that in the cicada mating game, after the male cicada puts on his best performance, the female signals her willingness to mate with an audible series of wing flicks. By a still not fully understood physiological mechanism, Massospora exerts mind control over an infected male cicada, causing him to mimic the female’s wing flick behavior. This results in horny male cicadas attempting to mate with Massospora infected males, further spreading the fungus through the cicadas’ populations.

Early in the Massospora infection cycle males and females with distended, distorted abdomens appear. Soon, fungal spore masses replace terminal abdominal segments. Sterile infected cicadas walk around and fly about, attempting to mate with uninfected cicadas and spewing spores into the environment while infecting their brood mates. Nearby, a healthy male cicada becomes entangled with an infected cicada in a bizarre pas de deux. In a strange twist of mind control, Massospora causes male cicadas to mimic the female’s wing-flick behavior, her coy signal of willingness to mate. Watch as a male uses his courtship call and attempts to woo a fungus-infected cicada that had just flicked its wings. His overactive libido will likely end in a lethal infection,n further spreading Massospora through cicada land. Videos by Michael Raupp and Paula Shrewsbury

A recent discovery of psychoactive compounds produced by Massospora suggests that these neuromodulators may play a role in altering the male’s behavior, contributing to the active transmission of the fungus by the cicada. Infected cicadas are flight capable and their peregrinations carry the fungus to new habitats as cicadas fly about. In low density populations of cicadas, mortality rates caused by Massospora range < 5% to ~ 25%. A second, more sinister wave of infection follows the first. In this stage, fungus-laden abdomens of infected cicadas and dying infected cicadas inoculate the soil with the resting spores of Massospora. While the loss of an abdomen spells instant death for a human, this is not the case for a cicada. Sensory and integrative neurological functions in the head and locomotory functions of flight and walking directed by the thorax remain intact despite the loss of the abdomen.  As the season of the cicada progresses throughout cicada land, keep an eye out for male and female Massospora victims as they walk about missing their abdomen, macabre reminders of a very clever fungus.

Acknowledgements

The wonderful articles “A specialized fungal parasite (Massospora cicadina) hijacks the sexual signals of periodical cicadas (Hemiptera: Cicadidae: Magicicada) by John R. Cooley, David C. Marshall, and Kathy B. R. Hill, “The ecology, behavior, and evolution of periodical cicadas” by K. S. Williams and C. Simon, and “Behavioral betrayal: How select fungal parasites enlist living insects to do their bidding” by Brian Lovett, Angie Macias, Jason E. Stajich, John Cooley, Jørgen Eilenberg, Henrik H. de Fine Licht, and Matt T. Kasson where used to prepare this episode.

This post appeared first on Bug of the Week

In last week’s episode, we watched periodical cicadas emerge from the ground after seventeen years, make a mad dash for a tree or other vertical structure, latch on, and shed their juvenile exoskeleton. Many fell to predators or simply failed to escape from their youthful skin and perished without enjoying a moment in the sun. But for the lucky ones surviving the first night of terror, the ghost-like newly molted cicada soon morphed into the spectacular, fully formed cicada bedecked with dazzling vermillion eyes, jet black body, and striking orange wing veins. With haste, survivors made their way to the relative safety of the treetops to complete their transformation into adults. Newly molted cicadas, termed teneral adults, spend the next several days waiting for their exoskeleton to harden before appendages used to insert eggs into branches, or other structures used in flight, sound production, and mating, become fully functional. As this maturation proceeds, cicadas move by foot or wing to treetops and underlying shrubs, vegetation or human-made structures to begin the mating game.

Acoustic signaling, the production of various sounds, is a key element in cicada reproduction. Just behind the thorax on either side on the male cicada’s body, hidden by the wings, is a drumhead-like structure called the tymbal organ. Powerful underlying muscles vibrate the tymbals, creating sound which is further amplified by hollow reverberation chambers within the abdomen of the cicada. While only the male sings, both males and females listen with an ear-like tympanum on the undersurface of their abdomen. Male cicadas have a profound repertoire of sounds. When under attack by a predator, a screechy alarm call issues forth from the cicada’s abdomen. An encounter with the alarm call likely disorients naïve would-be predators or bug geeks handling a cicada for the first time. Creating sound to escape predators is one thing, but the primary function of tymbals and their songs is to ensure the fidelity and perpetuation of the three species of periodical cicadas emerging as Brood X. To successfully reproduce, members of the same species must be in the same place at the same time to find a mate. Using unique and distinctive choruses, male cicadas sing loud and long to attract females and other males of their species to specific locations for the purpose of mate selection. The loudness of the big boy band of hundreds of cicadas singing in concert can range from 80 to more than 100 decibels. These choruses are often in fairly well defined locations such as a single large tree or group of trees. Near my home in Columbia, Maryland, a veteran ash tree has served as the party site for a raucous band of M. cassini for more than a week. Another nearby silver maple trees hosts a mellow chorus of M. septendecim.

A periodical cicada ascends to the treetop to join his brood-mates. Males create sound by vibrating tymbal organs on both sides of their abdomen just beneath their wings. Hundreds of males form load choruses to attract others of their own species. Watch as a pharaoh cicada cruises the chorus using his courtship song to locate an interested female. Nearby, another hopeful male gets the attention of a coy female who flicks her wings several times. Wing flicks accompanied by clicking sounds usually signify a willingness to mate. However, as the suitor closes in to seal the deal, his hopes are dashed when the lady changes her mind and flies away. On a nearby branch another male finds a mate and fulfills his biological imperative.

Once the gals show up to the chorus, it’s all about romance. When cicadas get eyeball to eyeball, the male cicada uses a variety of courtship songs to convince that special someone that she should be the mother of his nymphs. If his performance is good, she will communicate her willingness to mate with choreographed flicks of her wings accompanied by an audible click. Amidst the cacophonous rock concert in the treetops, these teen lovers consummate their interlude with a prolonged bout of mating. Males and females often remain joined for hours during these encounters. Do periodical cicadas really mime Woodstock 1969 every seventeen years? My busy suburban neighborhood lies in the flight path of a major international airport and on warm sunny days lawn mowers and other machines with small engines create a noisome serenade. It has been observed by several folks that cicadas will amp up the volume of their choruses as airplanes soar overhead or lawn mowers create their rackets nearby. A distinguished colleague recently offered that female cicadas likely choose a worthy mate by the loudness of his performance. Apparently, in a strategic competition to find a mate, boisterous, chorusing males are not to be outdone by the noisy contrivances of humans.

Mating cicadas may remain joined for hours. However, when the paparazzi show up and shatter the romance, this shy couple tries to escape the probing lens of the camera.

Acknowledgements

Bug of the Week thanks Dr. Shrewsbury for helping wrangle cicadas for photography and videography.We thank many members of print and non-print media for providing the inspiration for this episode.

This post appeared first on Bug of the Week

Last week we talked about a trickle, but not a flood of cicadas, here in the DMV. A few days in the mid – 70s with showers here and there changed the situation rather dramatically. In many areas in northern Virginia, Maryland, and DC hordes of cicadas appeared over the past several days. As the vanguard of Brood X arrived in fifteen states ranging from Georgia to New York in the east and states bordering the Mississippi to the west, their strange strategy for survival, predatory satiation, dramatically took center stage in millions of backyards. While annual cicadas depend on stealth and speed to survive, periodical cicadas play a bizarre “safety in numbers” game. By emerging by the billions almost simultaneously, they fill the bellies of every predator that wants to eat them and yet enough survive to perpetuate the three species known as Brood X.

During the next three weeks, billions of cicadas will make a jailbreak after seventeen years underground. The lucky ones will join a tidal wave of other nymphs as they ascend trees and other vertical structures at night. This late riser successfully shed her exoskeleton in the waning hours of night. After ascending the tree at dawn and pausing to expand her wings on the shell of a brood mate, she must wait several days for her body to harden before flying to the treetops to find her mate.

While holding a record for the longest juvenile period of any insect (termite queens live a longer adult life span at more than 50 years), they escape above ground predators for 17 years. However, their interment underground while sucking on plant roots comes with its own perils.  Three ancient oaks in a nearby park spawned thousands of cicadas in 2004. Five years ago, two of these veterans were removed and the root systems subsequently died. Conspicuously absent around the stumps this spring were any signs of cicadas or their exit holes. At the base of the remaining giant, another bumper crop of cicadas has made their appearance. Development also imperils cicadas beneath the earth. Homes, parking lots, driveways, office buildings and other forms of human development supplant trees with impervious surfaces, the death knell for cicadas. On the micro-level, even patios and stepping stones in a garden can prevent these teenagers from enjoying their brief moment in the sun.

Death comes in many forms to Brood X cicadas. Impervious surfaces like garden pavers prevent the nymphs’ escape from the earth. Pathogens kill many nymphs underground prior to emergence. Fierce carpenter ants feast on helpless newly molted adults on the night of their disinterment. Woodpeckers, grackles, mockingbirds, flycatchers, sparrows, and many other birds and small mammals, including foxes and squirrels, devour cicadas by night and day.  Clumsy nymphs ready to molt latch onto their kin, dooming themselves and their brood mates. Watch as one nymph dislodges another, sending it to a certain death on the ground below, a comical yet tragic ending to seventeen years underground and an almost completed life. Images of squirrel and grackle by Dan Gruner; Jack Bush provided the nighttime image of a fox.

The biggest winners in this game of life and death are all the creatures higher up the food web that benefit from the bounty provided by periodical cicadas. For the vanguard of cicadas storming the world above ground, the carnage will be great. Foxes, raccoons, squirrels, and dogs spent the last several weeks unearthing delectable cicada nymphs. Birds and non-feathered reptiles are feasting. Periodical cicadas are a bounty for many species of birds, a banquet resulting in larger clutches of eggs, shorter inter-clutch intervals, higher nestling body mass, and higher fledgling success during this year’s emergence of periodical cicada. In my neighborhood a pair of nesting hawks spends their afternoons swooping down to lawns below to catch cicadas and return them to a nest with some very healthy looking eyas.

Unfortunately, this run of moderately warm days with unusually chilly nights seems to have taken an unusual toll on cicadas. Many nymphs emerging from the earth near dusk with temperatures in the upper 60s, hit a developmental brick wall as temperatures rapidly dropped to the low 50s and 40s during the night. Failure to complete the process of shedding their nymphal skin seems to be accounting for unusually high levels of molting failure and death in these early risers. But for Brood X in the mid-Atlantic, good news may be just around the corner with a forecast of daytime highs in the 80s and nighttime lows in the 60s. Get ready for teenagers rockin’ in the treetops by this time next week.    

Acknowledgements

Bug of the Week thanks Randy for allowing us to visit her cicada sanctuary and Dan Gruner and Jack Bush for providing images. Two great references “Reproductive responses of sparrows to a superabundant food supply” by T. R. Anderson, and “Effects of superabundant food on breeding success and behavior of the red-winged blackbird” by C. E. Strehl and J. White were used to prepare this episode.

To keep current on what’s up with the 2021 Brood X cicada emergence in the DMV, check in with the Cicada Crew at the University of Maryland.

This post appeared first on Bug of the Week

In last week’s episode, we heard about the arrival of Brood X periodical cicadas in the deep South, Georgia, North Carolina, and Tennessee, where cicada adults are up and out of the ground and ushering in the main event in this region. This week we also viewed some great video of emerging cicada nymphs in northern Virginia near Tysons Corner. As an alum and emeritus of the University of Maryland, I was particularly intrigued by a reported sighting of periodical cicadas made by several Terp students on April 27th near our iconic Memorial Chapel. On the eve of Tuesday May 4, following a day of near record temperatures in the 80s punctuated by rain showers, a cicada safari seemed in order. High temperatures and the high relative humidity that follows a late afternoon storm are often the perfect conditions to trigger emergence of cicadas. After searching dozens of stately oaks near the chapel, around 10 pm I was rewarded with the discovery of cicada nymphs rising from their subterranean crypts after 17 years, and ascending a nearby willow oak. Not exactly the flood I was hoping for, but the gentle trickle of cicadas provided a pleasant ending to the safari. This week has seen a deluge of journalists and cicada enthusiasts hoping to witness the upcoming cicada tsunami in the DMV but, alas, Mother Nature is teasing us. With daily high temperatures forecast to be in the 60’s and several cloudy and showery days scheduled for the upcoming week, it looks like the massive emergence here in the DMV – the cicadapalooza – will be delayed just a bit. As my meteorologist friends assure me, this could all turn around quickly with a blast of warm, humid air from the south. Let’s keep our fingers crossed.

Cicada safaris often begin at dusk and stretch into the dead of night. At the base of a veteran oak tree, shed skins of cicadas provide a clue that the big jailbreak is near. As weather warms over the next several weeks, a cicada trickle becomes a cicada tsunami.

Another curious event happened this week while visiting a few cicada nymphs beneath the earth with a film crew from the BBC. The question arose about gender identity of cicadas, and was it possible to tell the guys from the gals. As with many sexually reproducing organisms on earth, the equipment for mating is fundamentally different between males and females. After unearthing several fifth instar Magicicada nymphs and examining their rear ends, it was easy to resolve this query. The male nymph bears a singular slightly enlarged bump at the tip of his abdomen, that when fully developed in the adult stage will be his intromittent organ, called an aedeagus. The nymphs destined to be a female have two darker triangularly shaped structures at the tip of their abdomen that will house the ovipositor of the female. The ovipositor is the appendage used to slit pencil sized branches and insert eggs into egg nests.  Images of the abdomens of males and females are provided here to help clarify the difference between the sexes. For adult cicadas, it is easier to tell the guys from the gals.

When warm weather returns, be on the lookout for adult cicadas and be sure to use the appropriate gender designation for the males and females when you greet them.

Acknowledgements

Bug of the Week thanks Billy, Stephen, and Mike and the BBC for providing inspiration for this episode. Thanks also to Richard Scott Rupert and the entire crew of the Arboretum, Botanical Gardens, and Landscape Services at the University of Maryland. Thanks also to Colette, Virginia, and Trinadee who discovered the magical oak that spawned these early rising cicadas at the University of Maryland.   

To keep current on what’s up with the 2021 Brood X cicada emergence in the DMV, check in with the Cicada Crew at the University of Maryland.

This post appeared first on Bug of the Week

Recent episodes of Bug of the Week explored elements of cicada biology and several frequently asked questions about the soon-to-erupt volcano of Brood X periodical cicadas. We dispelled the notion that cicadas were locusts, put to rest the idea that they hibernated for 17 years underground, explained what was up with all those holes in the ground, and provided an educated guess as to when they might be seen in our region. Save for a lone outlier that showed up early just outside of Towson on April 19th and another that emerged in Rockville a few days later, adult cicadas remained scarce not only in our area, but around the nation. Last week all of this changed with scores of adult cicadas coming out of the ground in Tennessee and North Carolina. Closer to home several eagle-eyed students witnessed emerging cicadas ascending one of the stately ancient oak trees on the College Park campus of the University of Maryland as night fell on April 27th.  With air temperatures in the 70s and 80s this week, rain expected, and soil temperatures bouncing around the mid-60s, conditions seem right for the massive jailbreak to begin in some locations in our region. For several other broods Bug of the Week has visited, a warm day with an afternoon thunderstorm seems to create favorable conditions to trigger an emergence. Perhaps the higher relative humidity that follows a rain facilitates the Houdini-like escape of the cicada from its nymphal skin and reduces the chance of an early death.

On the night of April 27th, 2021, students in an ecology course recorded periodical cicadas emerging from the soil and scaling an ancient oak tree on the campus of the University of Maryland, College Park. Due to its rich tree canopy and long history of Brood X cicada appearances, tens of thousands of periodical cicadas will emerge on campus over the next several weeks. Video credit: Colette Lord

Over the past weeks, several attendees viewing virtual presentations about cicadas wanted to hear the legend of blue-eyed cicadas. Are there blue-eyed cicadas and, more importantly, is there a reward if you find one? The answers are yes and yes. Eye color in insects is a somewhat complicated phenomenon and dependent on which species of insect you are talking about. One of the most well-known examples of eye coloration comes from your old freshman biology buddy, the fruit fly. Noble Prize Winner T. H. Morgan used his discovery of a white eyed mutant of the normally red eyed fruit fly, Drosophila melanogaster, to describe patterns of inheritance and create the first genetic maps. While beneath the earth as nymphs, periodical cicadas have white eyes devoid of pigments. During the year of emergence, eye color changes to a deep vermillion, a color similar in shade to that seen in many species of flies. The red color of fly eyes is created by a group of ommochrome and pteridine pigments known as screening pigments. These pigments filter white light and enable red wavelengths to assist the normal function of rhodopsin, a photosensitive pigment found in the eye of the fly. Mutations affecting the formation of pigments alter eye color in these and other flies. Is the same true for cicadas?  While failing to find a specific reference on the physiological mechanism governing eye color in cicadas, observing variation in cicada eye color is never a problem, if you observe enough cicadas. I see variation in color within every brood. The most common color is a deep red hue, but sometimes shades of orange, white, or beautiful pale blue are seen.

And what about the reward for finding a blue eyed cicada? Well, the reward is simply that you found one. As cicadas emerge, please take the time to look many in the eye and claim your reward. Happy hunting!

Acknowledgements

Bug of the Week thanks Colette, Virginia and Trinadee for their brilliant observations of periodical cicadas on our campus this week. Special thanks to Colette and Virginia for sharing their images and videos and to Dr. Dan Gruner for putting his ecology students on cicada reconnaissance missions. The interesting article “Colour in the eyes of insects” by D.G. Stavenga was consulted for this episode. 

This post appeared first on Bug of the Week

Before we hail the arrival of the first Brood X cicadas to emerge in Maryland, let’s answer a few frequently asked questions that have popped up repeatedly over the last few weeks. Several viewers and journalists have asked what periodical cicadas have been doing underground for the last seventeen years. Often this query is linked to a related ask about cicadas hibernating for seventeen years. Actually, periodical cicadas have been busy feeding and growing, albeit at a relatively slow pace, ever since they entered the ground in 2004. Yes, in a somewhat COVID-like existence, they have social distanced in subterranean chambers, not to halt the spread of disease, but likely to avoid competing with other cicadas feeding on tree roots. Although they are not the longest lived insect (some termite queens may live over 50 years), at 13 or 17 years as youngsters, periodical cicadas are purported to have the longest juvenile period of any insect.

Adding one more mystery to this magical creature is its strange pattern of youthful development. Immature cicadas are rightly known as nymphs rather than larvae. Larvae are the immature growth stages of insects with complete metamorphosis that have a pupal stage, like beetles, butterflies, bees and several other taxa. Cicadas have incomplete metamorphosis and skip the pupal stage, instead going through several nymphal stages. After hatching from an egg inserted into a tree branch by its mother, a tiny hatchling cicada known as the first instar nymph tumbles to earth and quickly dives underground. In the soil it locates a small root and taps into a vascular tissue, called xylem, where the nymph acquires nutrients and water by imbibing xylem fluids. Clever studies of cicada life underground by Chris Maier revealed surprising development patterns of periodical cicadas. This first nymphal stage of a 17-year cicada usually lasts only a year before it sheds its skin (a.k.a. exoskeleton) and graduates to the second instar nymph. However, after the first year, life in the remaining four stages of a nymph may vary dramatically. Dr. Maier discovered that second instar nymphs were found over a period of six years, third instar nymphs were distributed over eight years, fourth instar nymphs were found over ten years, and fifth and final instar nymphs were found over a seven-year period. Here is the amazing part, despite the apparent disparate and asynchronous rates of development, all of these youngsters managed to emerge from the earth in synchrony in year 17, right on schedule. This mystery is yet unsolved. What about 13 year cicadas? Well, they also scramble across the years at varying rates of development, only faster than the 17-year crew, and they too manage to emerge in synchrony.

In 2004, tiny cicada nymphs the size of a rice grain tumbled to earth, buried themselves, and began feeding on roots of plants. After shedding their skin a few times, they were the size of a jellybean several years later. By year fourteen they had grown to almost one inch in length.  Now cicadas are peeking out of the soil and putting the finishing touches on exit holes before they emerge. Soon the jailbreak will be underway as they dash to vertical structures to shed their skins and head to the treetops.

In a world underground, devoid of light and visual cues, how do periodical cicadas keep track of the years? One hypothesis has it that the annual fluxes of xylem fluids and compounds contained therein may allow cicadas to track the passing of years. In winter when deciduous trees have no leaves, a dramatic reduction in liquids flowing in xylem tissue takes place. In spring when leaves burst forth and transpiration draws water from the roots to leaves in the photosynthetic canopy, xylem pressure changes again. Perhaps, these fluxes are the annual cues to which cicadas “listen.” Another hypothesis not entirely independent from the aforementioned is that a yet unknown molecular clock ticks away the years somewhere within the tiny mind of the cicada in much the same way some dastardly circadian rhythm wakes me at 5:30 am irrespective of when my alarm is set. In addition to the long-term synchronization mentioned above, there is a short-term synchrony, a biological starter’s pistol that signals it is time to make a jailbreak from the earth in year 13 or 17. When soil temperatures reach a temperature of about 64 degrees Fahrenheit, it marks the time in spring when the world above ground is warm enough for cicadas to make a mad dash for a vertical structure, shed their juvenile skins, become adults, ascend trees, best fierce predators, fly to the treetops, make a wonderful, raucous chorus to woo their mates, and for the males, find that special someone willing to be the mother of his nymphs.

This week the vanguard of periodical cicadas appeared in Towson and Rockville, Maryland. The sighting of a periodical cicada in Towson on April 19, 2021 falls within a day of a similar sighting of another periodical cicada near Towson in 2020. A second sighting occurred in Rockville on April 23 of a cicada that emerged in a home from some potting soil that had been brought inside two days earlier. No doubt a couple days of cozy temps inside probably sped up its development, but these two sightings confirm that the cicadapalooza is just around the corner. Cicada-philes, before you get too excited, please look at the graph that accompanies this episode. Here in the DMV the great cicada tsunami is most likely to arrive from the middle to the end of May. With temperatures expected in the 70s and 80s this week, don’t be surprised if a few more early risers appear.  Keep your eyes open.

Acknowledgements

Bug of the Week thanks Jennifer and Tano Arrogancia, Gene Kritsky, and the Cicada Safari for sharing images of Brood X cicadas and providing the inspiration for this episode. The following references where used to prepare this story: “The ecology, behavior, and evolution of periodical cicadas” by K. S. Williams and C. Simon, “Thermal synchronization of emergence in periodical “17-year” cicadas (Homoptera, Cicadidae, Magicicada)” by J. E. Heath, “Combining Data from Citizen Scientists and Weather Stations to Define Emergence of Periodical Cicadas, Magicicada Davis spp. (Hemiptera: Cicadidae)” by M. J. Raupp, C. Sargent, N. Harding, and G. Kritsky. Gene Kritsky and Cicada Safari provided data used for the graphic of cicada emergence in 2020. We also thank Chris Simon for sharing her lecture notes of cicada development underground, Chris Maier for his studies of cicada biology, and John Cooley for enlightening discussions.

To learn more about periodical cicadas, please visit the Cicada Crew website at the University of Maryland.

This post appeared first on Bug of the Week