Squash and squash: Squash bugs, Anasa tristis

Homonyms, words with two or more meanings, are interesting constructs of any language. For example, take bark, it has a couple meanings. It can be the corky tissue protecting the outside of a tree or the vocalizations of furry, four-legged mammals that like trees for, well, you know. My dictionary defines squash as a noun meaning “vegetable of the gourd family” and as a verb meaning “to crush something with pressure.” Let’s look at the first meaning of squash. Squash, zucchini, pumpkins, and gourds are all delectable and nutritious members of the cucurbit family. However, humans are not the only ones that find these prickly plants scrumptious. In a previous episode of Bug of the Week, we met the dastardly squash vine borer, a caterpillar with the power to wilt even the toughest pumpkin vine. While admiring some squash vines in a community garden, I noticed several plants with wilted, yellow leaves. A closer inspection failed to find bad borers, however, the leaves of the squash were loaded with immature and adult squash bugs merrily sipping sap.

Squash bugs are members of the true bug clan, meaning they have an elongated beak for sucking liquid food, wings that are part membranous and part leathery, and, as juveniles, they are known as nymphs. We met other members of this cantankerous clique including bed bugs, brown marmorated stink bug, boxelder bug, and wheel bug in stories past. Both nymph and adult squash bugs consume fluids from their cucurbit hosts and problems arise when dozens of feeding squash bugs jab so many beaks into the vascular system of the plant. Inserting the beak damages the plant’s vascular system. In addition, squash bugs can transmit a nasty bacterium, Serratia marcescens, causing what is known as cucurbit yellow vine disease. These insults and removal of vascular liquids cause plants to wilt. When squash bugs are abundant, their damage can reduce the bounty produced by your squash and zucchini vines.

Who doesn’t love pattypan squash? But look out pattypan, those clusters of bronze eggs will soon hatch into tiny green and black squash bug nymphs. As they grow and molt, white wax cloaks their bodies. If you see adults roaming on your cucurbits, or discover eggs and nymphs, snatch them off and dispose of them in whatever way you like.

Fortunately, there are a few tricks you can use to foil the squash bug’s shenanigans:

1)       At the end of the year, rid your garden of decaying vegetation and remnants of vines and leaves. These refuges are used by adult squash bugs to survive the wild winter.

2)       In spring, plant varieties such as Butternut, Royal Acorn, or Sweet Cheese that are more resistant to squash bugs.

3)       I have spoken to gardeners who place floating row covers over their plants early in the season to help keep these buggers from colonizing their plants. If you go this route, remember to remove row covers when blossoms first appear. If you don’t, then pollinators cannot do their job. No pollination means no pumpkins, squash, or zucchini.

Been waiting for the second meaning of squash? If you see squash bugs, squash the squash bugs. Really, if you have just a few plants, it is relatively easy to inspect plants and when you find the golden-bronze eggs, green or whitish nymphs, or tawny adults, crush them.

If squashing squash bugs isn’t your thing, remove them from the plant and drop them into a vessel of soapy water. Squash bugs are poor swimmers and when they have expired their tiny bodies can be placed in the compost heap to nourish your garden next season. Have a squashing good time!  

Acknowledgements

Bug of the Week thanks community gardeners of Montgomery and Howard Counties for providing the inspiration for this episode and the backdrops for observing squash bugs.

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Echinacea, a.k.a. cone flower, renowned for its medicinal qualities as well as its beauty, is blooming at full throttle this week in gardens here in the DMV. Just after sunrise, the fragrance of cone flowers is delightful not only to humans, but also to a raft of pollinators. Bumble bees are usually the first arrivals in the morning, but shortly thereafter industrious bees, members of the halictid clan, arrive to collect nectar and pollen for youngsters in their colonies. The name “sweat bee” is a little goofy and somewhat misleading. These bees don’t sweat, but like sweat bees we visited at Bug of the Week some years ago, some halictids alight on humans and imbibe salt-rich perspiration. Guess this is why they are called sweat bees.

Unlike mason bees and plasterer bees we met in previous episodes, which are solitary with every female caring for her own young, halictid bees vary in their social structure. Some species like Agapostemon virescens adopt the solitary life style, while others like Halictus ligatus are eusocial (truly social) with queens producing non-reproductive daughters known as worker bees, tasked with foraging for nectar and pollen and tending the brood of their mothers. Colonies are founded in spring by females, survivors of winter’s ravages. The sweat bees we’re visiting this week adore cone flowers as a source of food, and both build nests in soil. Founding queens of Halictus ligatus gather pollen and lay eggs that hatch into daughters, worker bees, destined to help with caring for the young and gathering food for the colony. Some of these daughters will eventually become reproductively active and produce daughters and sons of their own. A fascinating study of Halictus ligatus by Miriam H. Richards and Laurence Packer discovered that when weather conditions were favorable, worker bees survived at greater rates and grew larger. Some of these large workers produced their own offspring. However, under less favorable conditions of temperature and food availability, workers were smaller and produced fewer offspring of their own, submitting to larger, more aggressive queens that produced the majority of offspring. Shifting conditions of temperature and food availability govern the social dynamics of halictid bees like Halitcus ligatus.

Cone flowers are a gold mine for many kinds of pollinators. Watch as female halictid bees, a.k.a. sweat bees, gather and store huge loads of pollen in pollen baskets, called corbiculae, on their hind legs. The smaller bee in the first two clips is Halictus ligatus or its sibling species, Halictus poeyi, and the last clip is the gorgeous Agapostemon virescens.  

Beautiful Agapostemon virescens, sometimes called “little green bees”, favor loamy soils with sparse vegetation as prime real estate to build their nests. Individual nests may contain more than 100 brood cells and, while more than one female has been observed in a single nest, this species is considered to be solitary. Once they find favorable plots of land, many Agapostemon virescens queens may move in and form large aggregations of nests. To enjoy these delightful native pollinators, consider letting part of your lush lawn go a little thin in a sunny spot to provide nest sites for nurseries of these bees. Both species of sweat bees and many others of their clan are generalist pollinators and a diversity of flowering plants provide food. However, on this week of Independence Day celebrations, Echinacea and other members of the Asteraceae are dynamite attractors of these beauties to your garden.  

Acknowledgements

Bug of the Week thanks Dr. Paula Shrewsbury for planting cone flowers that served as the backdrop for these delightful bees. Great references consulted for this episode include “Bees of Northwestern America: Agapostemon (Hymenoptera:Halictidae)” by  Radclyffe B. Roberts, “The Socioecology of Body Size Variation in the Primitively Eusocial Sweat Bee, Halictus ligatus (Hymenoptera: Halictidae)” by Miriam H. Richards and Laurence Packer, “The Insect Societies” by Edward O. Wilson, “The bees of the world” by Charles D. Michener, and “Bees, wasps, and ants” by Eric Grissell.  Special thanks to Sam Droege for identifying the halictids featured in this episode.      

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Last week scorching temperatures in our region provided an excellent reason to head for the hills for a cool hike. Forest trails of the Catoctin Mountain Park provide both the perfect location to escape summer’s heat and an opportunity to visit some of Mother Nature’s most interesting recyclers of organic compounds, millipedes. Millipedes are detritivores, creatures that consume organic matter including mosses, algae, and decaying vegetation that carpet the forest floor. Millipedes belong to the subphylum of the arthropods called Myriapoda, those with “many feet.” Do they really have a thousand feet? Nah, they don’t really have feet, but they do have legs and the record number of legs for a millipede is somewhere around 750. However, most millipedes have fewer than 400 legs. Young millipedes have only a few body segments, each of which bears a single pair of legs. As millipedes molt and grow, body segments with two pairs of legs each are added. Millipedes live two to seven years and can produce hundreds of offspring during their lifetime. Millipedes do not bite or sting, but several species secrete noxious chemicals from glands lining the margins of their body.  

On a stony forest trail, we happened upon two remarkable members of the millipede clan. The first was Narceus americanus-annularis, one of the true giants of the millipede world in North America. Its otherwise dull brown body was accented with beet-red legs and red bands encircling the body at each segment. These colors might serve as a warning of noxious defenses ready to be unleashed by the millipede. Unable to resist handling Narceus earned me an acrid reward of benzoquinones, foul smelling droplets of the millipede’s chemical defense. A bit further down the trail, we encountered one of the flat-backed millipedes, perhaps Apheloria virginiensis. Blending in with the forest floor was clearly not this creature’s game as it sported lemon-yellow legs, alternating bands of yellow and black along the back, and pink-hewed margins.  

Many legs of the millipede work in a wavelike fashion to propel these timid grazers as they search for organic matter to eat. Watch as it munches moss on the surface of a boulder. Nearby, another millipede dashes across a forest trail. Bright contrasting colors may warn predators not to mess with these chemically defended detritivores. Defensive compounds released by this millipede smell like almond extract.

When plucked from the ground, the smell of almonds filled the air and brought me back to my days of organic chemistry when benzaldehyde was the unknown compound on the lab practical. Benzaldehyde is the compound found in bitter almonds and is used as a flavoring in almond extract. Ah, but benzaldehyde is not the only compound found in Apheloria’s defensive secretion. The other more lethal moiety released by the millipede is hydrogen cyanide, a highly toxic irritant. Glad no one sniffed this millipede too deeply! Millipedes, important recyclers of organic matter, are well-protected by potent toxins and irritants that could make a bird, lizard, or toad think twice about messing around with these denizens of the forest floor.

Acknowledgements

We thank the intrepid hikers of the Catoctin Mountain: Erin, Ellie, Abby, Maggie, Jo, Paula, Laurie, and Kevin for providing inspiration for this episode. Thomas Eisner’s books “The Love of Insects” and “Secret Weapons” were used as resources for this story.

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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.

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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.

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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. 

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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.

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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.

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