When will we see cicadas in the DMV? Appearance of Magicicada spp.

In the past month, we peeked underground to see what periodical cicada nymphs were up to, untangled the misconception that cicadas are locusts, and learned to recognize signs of cicada activity by observing exit holes and excavations in landscapes created by foxes, raccoons, dogs, and other mammals. Recently, the most frequently asked question about periodical cicadas is “when will cicadas appear.” Bug of the Week has been tracking the life history of periodical cicadas for almost two decades so let’s look at some historical data and see what it reveals.

At the last emergence of Brood X way back in 2004, in University Park, MD, the first cicadas were up and out of the ground on May 6. University Park is a suburb just a few miles from a major urban heat island called Washington, DC. About 20 miles further north in less urbanized and cooler Columbia, MD, the big jail break happened a full nine days later on May 15, 2004 beneath an ancient crabapple tree in my front yard. It is well known that emergence dates of periodical cicadas can vary over relatively short geographic distances due to variation in exposure to the warmth of sunlight on the ground and local temperature regimes. In different locations, soil temperatures hit the magic 64 degrees Fahrenheit on different days. A soil temperature of roughly 64ᵒF is the proximate cue that the world above ground is now warm enough for cicadas to emerge, shed their skin, best hungry predators, climb to the treetops, and begin the awesome task of finding a mate and fulfilling the biological imperative to reproduce.

How can we tell when the big jailbreak is close at hand? The images and video accompanying this episode provide some clues. For the last several weeks, we witnessed almost-ready-to-go periodical cicadas peeking out from their galleries. In these images, notice that just behind its brilliant vermillion eyes, the dorsal surface of the cicada’s exoskeleton is uniformly tan in color. On the evening or day of emergence, notice how the exoskeleton of the cicada bears two jet-black patches just behind its eyes.  In more than a dozen emergences of periodical cicadas attended by the Bug Guy, this seems to be the clue that cicada emergence is very close at hand or underway. When you see these dark patches, the big show is about to begin.  

For seventeen years, nymphs of Brood X cicadas have been developing underground. While digging a hole in my yard in 2018, I discovered a quartet of periodical cicadas about 14 inches underground. Notice their white eyes and uniformly tan bodies. Last week, a periodical cicada not quite ready to emerge rested at the top of its exit gallery beneath a cinder block. Just behind its red eyes, the dorsal surface of the cicada is uniformly tan. On the evening of its emergence, notice how the dorsal exoskeleton of the fully developed cicada nymph bears two distinct black patches just behind its eyes.

In a previous episode of Bug of the Week in 2017, we reported sightings of impressive numbers of Brood X cicadas that appeared four years early. These cicadas are known as “stragglers.” Stragglers are periodical cicadas that emerge years prior to or after the major portion of their brood mates. Often, 17-year cicada stragglers emerge four years prior to the emergence date of rest of the brood. In 2017, Maryland Brood X stragglers appeared on May 14 in Columbia and Gaithersburg. In addition to emerging four years early, sometimes stragglers emerge one year early and this is exactly what happened in 2020.  Using data collected in 2020 from the brilliant Cicada Safari App, the very first cicada out of the ground was seen on April 19, just south of Towson, Maryland. This one was an extreme outlier. Cicada emergence really picked up in the DMV on May 14, and by May 24, 25% of emerging cicadas were out of the ground. By May 28, 50% of cicadas had emerged, and just few days later on May 31, 75% of all cicadas had emerged in DC, Maryland, and Northern Virginia. So, if 2021 is anything like 2020 or previous years for that matter, cicadas will be regularly seen as a trickle in our region in the first two weeks of May with a tsunami hitting in the last two weeks as these teenagers are up and out for the cicadapalooza. Here in the DMV in 2020, the last cicada to emerge was reported on June 14. Due to a normal life span of two to four weeks, don’t be surprised to see adult cicadas alive and well into the waning weeks of June, but, sadly, by the 4th of July, their moment in the sun will be all but finished and nothing but a fading memory. Remember, the great W. C. Fields once opined “Never work with children or animals” and I will add, especially with periodical cicadas, “or when it comes to weather”. When will we see cicadas in the DMV? Perhaps, we will just have to wait and see.

Acknowledgements

Bug of the Week thanks Scott and Jordana Snider for providing the inspiration for this episode. Three cool articles, “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, “The ecology, behavior, and evolution of periodical cicadas” by K. S. Williams and C. Simon”, and “Thermal synchronization of emergence in periodical “17-year” cicadas (Homoptera, Cicadidae, Magicicada)” by J. E. Heath formed the foundation for this episode.

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

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Two weeks ago we began a series on the upcoming appearance of Brood X cicadas and visited an almost ready to emerge member of the graduating class of 2021 in a shovelful of soil. Last week we learned that cicadas are not locusts. This week we’ll talk about all of the holes and other signs of cicadas that are popping up all over the place in the DMV. But first, let’s talk about the feast that is underway for small wild and domestic mammals as periodical cicadas prepare an exit strategy from their seventeen years underground. This feasting stage began almost two months ago when a curious homeowner sent fascinating images of impressive excavations of turf beneath a fine old tree. The perpetrator of this crime was a pesky raccoon intent on digging for its dinner. The lawn was, well, just collateral damage on the way to a fine meal.  While the identity of the subterranean morsel was never confirmed, this type of behavior is characteristic of many small mammals that will find cicada nymphs and adults irresistible this spring and go to great lengths to find them.

A couple of weeks ago while emptying some coffee grinds in the compost at 6:30 AM, I surprised a very handsome and healthy red fox in the process of excavating a thirty-foot-long patch of earth beneath my stately Burford holly. A couple quick turns of the shovel revealed several Magicicada nymphs about six inches below the surface of the earth. Casual site visits to my neighbors’ gardens and further inspection of my landscape revealed several locations where fox and friends have been busy in Columbia, Maryland. Both foxes and raccoons have excellent night vision, a must for their nocturnal forays, and an extremely keen sense of smell that allows them to detect prey beneath layers of fallen leaves and soil. These wild small mammals are not the only ones whose special creature powers include super olfaction. A dog’s sense of smell is estimated to by more than 10,000 times more acute than a human’s. And yes, this week several reports arrived to the Cicada Crew posing the question: “Why is the dog digging up my yard?” Chances are good that Fido knows a good snack when he smells one. Please, just don’t let him eat too many.

Beneath a maple tree a very dusty cicada peeks out of its hole, while beneath a concrete block another nymph shapes its gallery with clever forelegs before plunging back into the tunnel, avoiding the lens of the camera. 

Now is an excellent time for a suburban safari to your backyard to spot signs of the arrival of periodical cicadas, which could happen sometime soon. Look for holes in the soil about the size of a dime within the dripline beneath trees that have been in the ground for seventeen years or more. Oak, maples, crabapples, and hollies seem to be the big winners in my landscape at the moment. In addition to holes, periodical cicadas often build domed caps known as turrets over their escape tunnels. This may be more common in wetter soils. If your landscape includes stepping stones or slate pathways over soil, lift a few and you may discover lateral tunnels as cicadas encounter the impenetrable barrier and attempt to make their way to the edge of the barricade to reach the world above ground.

No holes under trees? Don’t panic, new holes are showing up in landscapes on a daily basis.  Reports of cicada nymphs above ground are also arriving. In fact, while raking up leaves and branches yesterday, I unearthed several nymphs that must have been dislodged from the soil as I removed the leafy layer above their galleries. Coloration of their exoskeleton indicated that they were not quite ready to make the jailbreak from the earth. I returned them to the soil. Recently, someone asked how cicadas moved about underground and how did they construct their exit galleries? The answer is clever adaptations. Their forelegs bear greatly expanded femurs and tibias which act like the blade of a shovel to move soil. Millions of years of evolution for a life in two worlds, one underground and one above the earth, have perfected the tools necessary for cicadas to succeed in both.        

Acknowledgements

Bug of the Week thanks L. Kenigsberg for providing the nice image of lawn pillaged by a raccoon that served as the inspiration for this episode. Kristin Jayd and Paula Shrewsbury also provided images and assisted with videography.       

Join The Bug Guy tonight for an in-depth Zoom event with the Prince Georges County Alumni Network: Return of Periodical Cicadas – Fear, Fascination and Fun in 2021. University of Maryland Professor Emeritus Mike Raupp will explore the natural history, ecology, and behavior of the seven species of periodical cicadas indigenous to North America. Preregistration required.

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Last week we visited Brood X periodical cicada nymphs preparing to exit the earth after a 17-year interment underground. This week let’s settle the score on an often-asked question about cicadas, “Are they locusts?” The notion that periodical cicadas are a type of locust dates back to some of the earliest biologists and religious leaders struggling to understand the strange and unprecedented appearance of legions of large insects emerging from the earth every 17 years. In 1666 Henry Oldenberg, a German theologian and natural historian was, perhaps, the first to note the peculiar similarity between periodical cicadas in North America and biblical plagues of locusts which occurred periodically in parts of Eurasia. Oldenberg referred to the cicadas as “flyes” rather than locusts. Some 49 years later in 1715, the Reverend Andreas Sandel of Philadelphia described cicadas as “locusts”, noting that this was the vernacular name given to these creatures in the English colonies. But his reference to locusts was not to the eighth biblical plague of Egypt; rather, his allusion was to the fact that Native Americans consumed cicadas in much the same way that John the Baptist had eaten locusts. And so, Sandel concluded his account by stating “These locusts lasted not longer than up to June 10, and disappeared into the woods.”

We met lubber locusts in a previous episode of Bug of the Week. Locusts belong to an order of insects called Orthoptera and are members of the family Acrididae. Acridids are commonly called grasshoppers and these cosmopolitan insects number more than 10,000 species worldwide. Some, like the differential grasshopper, are common residents in landscapes where they munch flowers and vegetables. Others, like the migratory locust, Locusta migratoria, likely the real culprit of the eighth plague of Egypt, are widely distributed across several continents. They can attain astounding densities, become highly mobile, and use powerful jaws to devour vast swaths of vegetation as they rage across the earth.

Watch as a grasshopper uses its jaws to chew leaves of a small plant. Locusts are a type of grasshopper. By contrast, cicadas like this Brood X periodical cicada sip fluids with sucking mouthparts inserted into the vascular tissue of plants. Notice the sucking mouthparts point downward between the front legs of the cicada. Excess fluid from their liquid meals is excreted by cicadas. Tropical cicadas produce torrents of liquid waste as they feed. Fortunately for millions of folks who will be visited by periodical cicadas this year, Brood X does not generate cicada showers of this magnitude.

Periodical cicadas belong to an order of insects called the Hemiptera (true bugs). They are members of the family known as the Cicadidae. More than 3,000 species of cicadas inhabit the earth and they are found on all continents except Antarctica. However, the magical periodical cicadas occur only in the eastern half of the United States – lucky us. Periodical cicadas lack the biting jaws of locusts; instead, their mouthparts consist of a soda straw-like affair. Both nymphs and adults insert this proboscis into vascular tissue called xylem which is found in roots and stems of plants. Cicadas suck nutrients and water into their digestive tract with these mouthparts. Excess fluid is excreted from the digestive tracts of cicadas and there have been reports of folks standing beneath a tree loaded with cicadas who felt a gentle shower emanating from the tree above. When billions of cicadas are about, like John Fogerty crooned, you could see rain “commin’ down on a sunny day, yeah.”   

So, to answer the question, “are cicadas locusts?” Nope.

Acknowledgements

Bug of the Week thanks Gene Kritsky for providing the inspiration for this episode and acknowledges his wonderful book “Periodical Cicadas: The Plague and the Puzzle”, which was used as a reference for this episode. We also thank Dr. Shrewsbury for helping wrangle cicada nymphs featured in this and last week’s episode.

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During the past month, Bug of the Week’s peregrinations have visited Chilean chinchemolles, Peruvian beetles, Costa Rican arachnids, and Floridian tiger moths. This week we hop-scotch a thousand miles north to the DMV to check on the progress of Brood X periodical cicadas. During the past several weeks the Cicada Crew at the University of Maryland has been busy reassuring journalists and the public at large that, yes indeed, Brood X cicadas a.k.a The Great Eastern Brood, will appear in 15 states and the District of Columbia in the eastern half of the USA this spring. While issuing these claims, a little voice whispers something like “What if climate change or some yet unknown manifestation of the insect apocalypse has intervened in the last 17 years and cicadas don’t appear?”

To quell a bit of rising panic that prognostications of a spectacular cicada-palooza might prove false, last week we visited our favorite Brood X cicada patch to see how those rambunctious teenage cicadas were doing. The first strike of the shovel unearthed a fully grown cicada nymph. Already under construction was his escape tunnel, the passageway from the realm of darkness where he sipped xylem liquid from the roots of plants for the last seventeen years to the world of light where he will join legions of brood mates in a rambunctious mating game. This discovery is strikingly similar to a dire account published in the Annapolis gazette on April 3, 1751. An anonymous colonist wrote the following “We are informed … in some Places the Locusts have been found in great plenty, just under the surface of the Earth, almost at their full growth.  May God avert our impending Calamities!” This ominous report most likely refers to Brood XIX, a brood of thirteen-year cicadas found in what is now St. Mary’s County, Maryland, the former colonial capital of Maryland and still an important agricultural center 270 years after this account.

Seventeen years ago in the spring of 2004, periodical cicadas laid eggs in treetops. In summer, the eggs hatched and tiny nymphs tumbled to earth and burrowed down to feed on tree roots for the next seventeen years. Fast forward to 2021. Brood X periodical cicadas are now poised to exit their subterranean crypts and make a boisterous entry to the world above ground.

So, if you are concerned that periodical cicadas may not show this spring, put your fears to rest. In parts of Delaware, Georgia, Illinois, Indiana, Kentucky, Maryland, Michigan, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia and West Virginia, the vanguard of Brood X periodical cicadas will make their presence known in a month or so. We will explore much more about these remarkable creatures in upcoming episodes.

Acknowledgements

The wonderful book “Periodical Cicadas: The Plague and the Puzzle” by Gene Kritsky, and the source of all things cicada, the Cicada Mania website, were used as references to prepare this episode. To learn more about Brood X periodical cicadas in Maryland, visit our 2021 Cicada Brood X information clearinghouse at https://cicadacrewumd.weebly.com/

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During the past month, Bug of the Week’s peregrinations have visited Chilean chinchemolles, Peruvian beetles, Costa Rican arachnids, and Floridian tiger moths. This week we hop-scotch a thousand miles north to the DMV to check on the progress of Brood X periodical cicadas. During the past several weeks the Cicada Crew at the University of Maryland has been busy reassuring journalists and the public at large that, yes indeed, Brood X cicadas a.k.a The Great Eastern Brood, will appear in 15 states and the District of Columbia in the eastern half of the USA this spring. While issuing these claims, a little voice whispers something like “What if climate change or some yet unknown manifestation of the insect apocalypse has intervened in the last 17 years and cicadas don’t appear?”

To quell a bit of rising panic that prognostications of a spectacular cicada-palooza might prove false, last week we visited our favorite Brood X cicada patch to see how those rambunctious teenage cicadas were doing. The first strike of the shovel unearthed a fully grown cicada nymph. Already under construction was his escape tunnel, the passageway from the realm of darkness where he sipped xylem liquid from the roots of plants for the last seventeen years to the world of light where he will join legions of brood mates in a rambunctious mating game. This discovery is strikingly similar to a dire account published in the Annapolis gazette on April 3, 1751. An anonymous colonist wrote the following “We are informed … in some Places the Locusts have been found in great plenty, just under the surface of the Earth, almost at their full growth.  May God avert our impending Calamities!” This ominous report most likely refers to Brood XIX, a brood of thirteen-year cicadas found in what is now St. Mary’s County, Maryland, the former colonial capital of Maryland and still an important agricultural center 270 years after this account.

Seventeen years ago in the spring of 2004, periodical cicadas laid eggs in treetops. In summer, the eggs hatched and tiny nymphs tumbled to earth and burrowed down to feed on tree roots for the next seventeen years. Fast forward to 2021. Brood X periodical cicadas are now poised to exit their subterranean crypts and make a boisterous entry to the world above ground.

So, if you are concerned that periodical cicadas may not show this spring, put your fears to rest. In parts of Delaware, Georgia, Illinois, Indiana, Kentucky, Maryland, Michigan, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia and West Virginia, the vanguard of Brood X periodical cicadas will make their presence known in a month or so. We will explore much more about these remarkable creatures in upcoming episodes.

Acknowledgements

The wonderful book “Periodical Cicadas: The Plague and the Puzzle” by Gene Kritsky, and the source of all things cicada, the Cicada Mania website, were used as references to prepare this episode. To learn more about Brood X periodical cicadas in Maryland, visit our 2021 Cicada Brood X information clearinghouse at https://cicadacrewumd.weebly.com/

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For the last several weeks we have escape lingering chilly and dreary weather in Maryland to visit elegant phasmatids in Chile, pleasing fungus beetles in Peru, and creepy whip spiders in Costa Rica. This week we return to the good old USA and the semi-tropical warmth of southern Florida to meet a pair of breathtaking tiger moths and their similarly stunning offspring. While many tasty insects like lantern flies, beetles, and katydids depend on cryptic coloration to avoid the hungry jaws of predators, the spectacular iridescent colors of the polka-dot wasp moth and the spotted oleander caterpillar moth shout “here I am, eat me if you dare!” How then do these scaly winged harlequins escape the sharp beaks and pointy teeth of vertebrate predators? Two schemes are at play.

First, the general resemblance of these non-stinging moths to a stinging wasp probably brings pause to hungry birds that have learned to avoid making meals of painful, stinging insects. The second defense lies in the food consumed by these moths in their youth. Larvae of the polka-dot moth are known as oleander caterpillars and larvae of the spotted oleander caterpillar moths are known as … well, take a wild guess. Their diets include leaves of oleander, a beautiful but deadly woody shrub brought to the New World by European colonists.

Oleander is a toxic member of the family Apocynaceae. Leaves, flowers, and fruit of oleander are laced with heart-stopping poisons known as cardiac glycosides. We were introduced to cardiac glycosides in the Apocynaceae in a previous episode where we learned of the ability of dogbane beetles to acquire these compounds and use them as a defense against predators. Like their milkweed feeding cousins the monarch butterflies, oleander caterpillars ingest and store cardiac glycosides that are passed along to the adult stage where they serve as dietary punishment for predators attempting to eat the glycoside-laced moths. The contrasting pattern of black dots on a bright orange background of the polka-dot moth caterpillar and the white splotches on the body of the spotted oleander caterpillar, convey strong visual images and a reminder that dining on either of these caterpillars can result in disagreeable digestive consequences. Striking warning colors and patterns are called aposematic coloration, a clever strategy employed by monarch butterflies, milkweed bugs, dogbane beetles, yellow jackets, Asian giant hornets, and many other colorful insects we have visited.  

Watch as the spotted oleander caterpillar dines on an oleander leaf. Like its native North American cousin, the oleander caterpillar (larva of the polka-dot moth), the spotted oleander caterpillar consumes foliage of this poisonous woody shrub in south Florida. Noxious cardiac glycosides obtained by the caterpillar from oleander may be passed along to the adult moth to dissuade attack by hungry predators.  

The female polka-dot moth truly is gorgeous and it is little wonder that males of this species find such a beauty irresistible. But finding a mate is challenging for small moths in big world. Many female moths and other insects solve this problem by using chemical attractants called pheromones to signal their willingness to play the mating game. Most female moths release pheromones from specialized abdominal glands that help guide otherwise haplessly searching males to their connubial reward. However, the female polka-dot moth relies on yet another strategy to attract her mate.  By vibrating plates called tymbals on the sides of her thorax, the female moth creates a rhythmic clicking sound, a kind of a mothy “yoo-who” to attract a suitor. In return, the male adds his own clicks to create an ultrasonic duet. Unfortunately, their love songs are beyond the range of the human ear. However, if the lucky couple harmonizes successfully, the result of their union may be dozens of tiny orange caterpillars decorating oleander. If travel brings you to sunny south Florida for spring break or a welcome escape from a lingering winter, be sure to visit an oleander or two and perhaps you will catch a glimpse of these beautiful moths or their interesting aposematic offspring.

Acknowledgements

To learn more about the polka-dot wasp moth and the spotted oleander caterpillar moth please visit the wonderful Featured Creature articles by H.  McAuslane, “Oleander caterpillar, Syntomeida epilais…” and  “Spotted oleander caterpillar moth (suggested common name), Empyreuma pugione…”. These web pages and two fascinating articles, one by M. Rothschild and her colleagues “Cardiac glycosides (heart poisons) in the polka-dot moth Syntomeida epilais Walk. (Ctenuchidae: Lep.) with some observations on the toxic qualities of Amata (=Syntomis) phegea (L.), and another by M. Sanderford and W. Conner, “Courtship sounds of the polka-dot wasp moth, Syntomeida epilais” were used to prepare this episode. 

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As Old Man winter refuses to completely relinquish his grip on much of North America, Bug of the Week continues its adventures in warmer places. In recent weeks we visited charming chinchemolles in Chile and beautiful fungus beetles in the Amazon Basin. This week we cross the equator and head 1,750 miles north to the Osa Peninsula of Costa Rica for a nighttime encounter with one of the creepiest arachnids on the plant, the whip spider, aka tail-less whip scorpion or amblypygid. To witness the grim mien of this creature, one must don a headlamp, grab a flashlight, and plunge into the rainforest, best done with a trusty guide. Unlike distant relatives that often hunt by day, like crab spiders and jumping spiders, these denizens of the dark lurk in caves, hide in hollows beneath rocks, galleries in the soil, or holes in trees during daylight hours. By night they hunt and ambush prey. 

While other arachnids such as spiders and true scorpions amble about on four pairs of legs, whip spiders use just three pairs for their nocturnal strolls. The fourth pair of legs found at the front of the creature is extraordinarily long and loaded with sensory structures to detect odors and objects including mates, offspring, and prey. These so called “whips” can be three to six times the length of the body and give the whip spider its common name. Whips can move in almost a complete circle around the amblypygid and are very useful for detecting objects ahead, behind, above, and to the sides of the creature in a world of darkness. Just in front of the whip-like legs is a pair of scary hinged appendages known as pedipalps. Pedipalps snag prey in much the same way the powerful forelegs of the praying mantis capture their victim. As a tasty morsel enters range, a rapid strike of the pedipalps ensnares the prey in comb-like teeth. Usual meals include crickets, cockroaches, spiders and moths, but small lizards and even fish are known to be eaten by these fierce predators. Once captured, the victim is pulverized by two grinding jaws called chelicerae. Digestive enzymes are added to the pulpy mass and the whip spider ingests the liquefied meal. 

A nighttime walk along a rainforest trail is full of spooky encounters, including ones with amblypygids. Watch as the whip spider senses the approaching danger of a giant finger and jets out of harm’s way. At one tenth of normal speed see how the whip-leg of the arachnid reaches back to examine the intruder before turning on the warp drive to escape.

As frightening as whip spiders appear, they are truly harmless to humans. In fact, some species have several admirable and somewhat endearing behaviors. One such behavior is a fine sense of direction. While wandering about the rainforest at night it is easy to get lost. On more than one occasion hapless adventurers have disappeared into a ravine while searching for a trail in dense tropical vegetation. Research has shown that some whip spiders can find their way home after being moved more than 30 feet away from their refuge, all this without Google maps. For any mothers who might be reading this episode, think about the calories you burn lugging youngsters about when they want to be picked-up. Whip spiders lay from 10 to 90 eggs at a time. Mother whip spiders typically carry their young on their backs for several weeks after offspring hatch from eggs. In captivity, females of the Floridian whip spider, Phrynus marginemaculatus, continue to interact with their offspring for several months after the babes have departed from their mother’s back. Mothers were observed to move between small clusters of young ones. In captivity, females and offspring frequently engaged in gentle mutual stroking with their whip-like legs. How often these fascinating behaviors happen in the wild remains to be seen. The message conveyed by the mutual stroking is known only to the whip spider and her young, but on a dark night in the Costa Rican rainforest, a gentle touch from mom could be a comforting signal even to a whip spider.

Acknowledgements

Bug of the Week gives special thanks to Carlos and the other nocturnal adventurers at Aguila de Osa who were the inspiration for this episode. Kenneth J. Chapin and Eileen A. Hebets’ treatise “The behavioral ecology of amblypygids”, and the wonderful article “Social behavior in Amblypygids, and a reassessment of arachnid social patterns” by Linda Rayor and Lisa Anne Taylor, were used as references for this episode. To learn more about whip spiders, please visit the following website: https://theethogram.com/2018/01/23/creature-feature-tailless-whip-scorpion/

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This week Bug of the Week continues its peregrination south of the equator. Let’s head north from Villarrica volcano in Chile some 2,000 miles to the western Amazon Basin for a visit with ridiculously beautiful beetles in the rainforests surrounding the Tambopata River. These forests, some of the most diverse on the planet, receive more than 90 inches of rainfall annually. As you might expect, the massive turnover of vegetation coupled with abundant rainfall, heat, and humidity provide superb conditions for the growth of fungi. Thousands of species of fungi call the rainforest home. As fungi play an important role in recycling refractory plant materials like cellulose and lignin, they in turn provide food for a diverse horde of hungry insects. Among the most spectacular of these insects are beetles belonging to the Erotylidae clan, the pleasing fungus beetles. Pleasing fungus beetles are a large and diverse group of insects found in many parts of the world, including here in Maryland. A subset of pleasing fungus beetles known as lizard beetles are plant feeders. Those that bore into stems of legumes are considered pests. The beauties featured in this episode are members of the genera Erotylus and Gibbifer, consumers of fungi as both larvae and adults. Indigenous folks of the Tambopata call the gorgeous black, yellow, and red striped Erotylus, “ladybeetle”, a term we reserve for members of the Coccinellidae family. This dazzling beetle is also known as the zig-zag beetle. It’s funny how common names of insects mean different things in different places.

Natural wonders await discovery in rainforests along tributaries of the mighty Amazon. Brilliant contrasting colors backed by chemical defenses likely enable this delightful Erotylus beetle, sometimes known as the zig-zag beetle, to move about in broad daylight with impunity. Grooming one’s body seems to be an important pastime for these beetles.

The stunning coloration of these beetles is thought to be aposematic, distinctive coloration meant to send a warning of distastefulness to predators, in much the same way the orange and black colors of monarch butterflies and milkweed leaf beetles warn birds not to mess with them. Many species of beetles, including pleasing fungus beetles and lady beetles, can release blood from their joints and other apertures in a behavior known as reflex bleeding. A recent study of pleasing fungus beetles in Germany found a veritable witches brew of aromatic compounds – alkenes, ketones, acids, and yet unknown compounds – released as secretions from glands and in the blood of adult beetles. Several components found in the secretions and blood of the pleasing fungus beetle were repellent to an important group of predators – ants, rulers of the forest floor. These compounds also have significant antimicrobial activity, a handy defense in a microbe-packed rainforest. Although the deep rainforest is sometimes dark and dank, discovery of pleasing fungus beetles, recyclers of plant recyclers is always an illuminating experience.   

Acknowledgements

Bug of the Week thanks the crew of the Posada Amazonas for providing the inspiration for this episode. Two interesting articles “First insights into the chemical defensive system of the erotylid beetle, Tritoma bipustulata” by Kai Drilling and Konrad Dettner, and “Beetles (Coleoptera) of Peru: A Survey of the Families. Erotylidae Latreille, 1802” by Joseph V. McHugh and Caroline S. Chaboo were used to prepare this episode.

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With outdoor insect activity still agonizingly slow here in the DMV, it’s time to jump on a plane and escape the chilly rains of Maryland’s winter and discover fascinating and beautiful insects in warmer parts of the world. Let’s head some 5,000 miles south to the base of the Villarrica volcano near Pucón, Chile. In a Jurassic Park-like setting, ancient Gondwanan trees such as Nothofagus and Araucaria cling to hillsides. Here along a rushing river at the base of the volcano we discovered the giant elegant phasmatid, locally known as the chinchemolle, unabashedly grazing on clover and other herbaceous plants lining the stream bank. In previous episodes we met cryptic phasmatids from Costa Rica, Vietnam, Australia, Florida, and Maryland doing their best to look like twigs or dead leaves as they hid their somewhat long gangly bodies from the hungry eyes of predators. Unlike their shy cousins, this monster of the insect world does not attempt to hide from its predators. Oh no, just the opposite. These gaudy herbivores visually warn their enemies not to mess with them lest they risk a nasty surprise. The striking adult male elegant walking stick bedazzles onlookers with brilliant scarlet bands encircling its jet black body. White splotches at the leg joints complete a “look” designed to catch a vertebrate’s attention. The female chinchemolle, while more subtly adorned, is also striking in appearance with her army-green body ringed with orange bands.

Whether it’s a dash on a riverbank or dining on tender leaves, striking coloration of the male chinchemolle warns predators not to mess with him. Notice the opening to the secretory gland just behind its head. Defensive fluid discharged from this opening thwarts attacks by hungry predators.

While most other members of the walking stick clan try to avoid predators by mimicking plant parts and moving very slowly, these brightly colored active ground dwellers have another trick up their sleeve – or should we say, behind their head? The first segment of the thorax bears two openings leading to large secretory glands just beneath the exoskeleton of the insect. These glands produce a highly irritating, noxious ketone that can be squirted into the face of an attacking bird, lizard, or mammal. In fact, there are reports of serious eye injury to humans who looked just a little too closely at Floridian walking sticks we met in a previous episode and were rewarded with a squirt in the face. One scientific report declares that local residents of Chile know better than to challenge the chinchemolle to a stare-down, lest they risk the peril of pain and temporary blindness. However, a Bug Guy from North America could not resist handling the chinchemolle and when I stared into the eyes of the large phasmatid, it only stared back. If I wasn’t certain that insects lack eyelids, I could have sworn that it gave me a wink.     

References

Bug of the Week thanks Dr. Audrey Grez of the University of Chile for identifying the chinchemolle and providing the inspiration for this episode. The following references were used in preparation of this episode: “4-Methyl-1-hepten-3-one, the Defensive Compound from Agathemera elegans (Philippi) (Phasmatidae) Insecta” by Guillermo Schmeda-Hirschmann, and “Defensive spray of a phasmid insect” by Thomas Eisner.

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With ambient temperatures still hovering around the freezing mark, mischievous plant pests would seem months away. However, as days lengthen, the strong winter sun delivers much more energy to house plants, especially those placed near large picture windows with a southern exposure. For pests like spider mites, elevated temperatures can cut generation times by more than half. This and a few other factors we will learn in a moment contributed to a seemingly overnight explosion of spider mites on one hapless houseplant in my living room. Here’s part of the back story. When new plants arrive in a household, it’s always a good idea to give them a careful inspection just to see if they might be harboring uninvited guests. Keeping a watchful eye on new arrivals for a couple of weeks is also a good idea just to see how they are doing and observe any hitchhikers that may have accompanied them from the plant shop. Having failed to follow these ounce-of-prevention rules, a new arrival to our home recently blossomed into a spectacular outbreak of twospotted spider mites.

Mites are not insects. They belong to a related clan of arthropods, a subdivision of Arachnids called Acari. Unlike insects that have three body regions, spider mites have only two, a small region bearing the mouthparts and a large region bearing legs that comprise the rest of the body. The mite’s development starts with an egg that hatches into a 6-legged larva which molts into an 8-legged nymph. One more nymphal stage occurs before the mite sheds its skin and becomes an adult.

Twospotted spider mites are infamous worldwide as a major pariah of vegetables grown in fields and greenhouses, large and small fruits, ornamental trees and shrubs, and herbaceous ornamental plants, including those growing in front of my picture window. These cosmopolitan rascals feed on more than 200 plant species worldwide. They injure plants by piercing cells with tiny needle-like stylets that rupture cell membranes. Nutritious cell contents are then sucked into the digestive tract of the mite. By removing the green photosynthetic contents of cells, tiny white spots accrue on the leaf surface, creating a type of injury called stippling. When spider mites are abundant and their feeding prolonged, leaves may turn white as thousands of stipples coalesce. Eventually leaves discolor and may turn yellow, bronze, or brown before dropping from the plant. Heavily infested plants often appear to have encountered a blowtorch.

One fascinating and unique attribute of spider mites is their ability to produce silk. Super strong silk fibers function as mite highways connecting one part of the plant to another. Silk also provides a protective refuge from predators and adverse climatic conditions and acts as a substrate for depositing eggs and communicating with other members of the species.

In the warmth of a sunny window, populations of twospotted spider mites explode. A cloak of fine silk spun by thousands of spider mites provides a highway for the tiny suckers to move from one branch to another. In addition to transport, silk provides a refuge from predators and the perfect place for spider mites to deposit translucent spherical eggs. Heavy infestations like this one are often best resolved by disposing of a plant before mites spread to others.

Under natural conditions outdoors, twospotted spider mites are beset by attacks of predatory ladybeetles, lethal minute pirate bugs (arrrggghhh!), maniacal lacewing larvae, and predatory mites, among other beneficial insects. Unfortunately, these heroes are conspicuously absent from my living room. With thousands of spider mites already sucking the life from my plant, legions of mite eggs ready to hatch, generation times growing ever shorter in the strong winter sun, and a dozen uninfested house plants cowering nearby, the hapless house plant has now joined the remnants of last season’s vegetables in the compost pile. In a final act of contrition, plant and pests will fuel generations of microbes and decomposers like pillbugs and soldier flies we met in previous episodes in an ongoing circle of life.

Acknowledgements      

Fascinating articles including “The silk of gorse spider mite Tetranychus lintearius represents a novel natural source of nanoparticles and biomaterials by Antonio Abel Lozano-Pérez, Ana Pagán, Vladimir Zhurov, Stephen D. Hudson, Jeffrey L. Hutter, Valerio Pruneri, Ignacio Pérez-Moreno, Vojislava Grbic’, José Luis Cenis, Miodrag Grbic’ & Salvador Aznar-Cervantes”, and “ Featured Creatures, Common name: twospotted spider mite scientific name: Tetranychus urticae Koch (Arachnida: Acari: Tetranychidae)” by Thomas R. Fasulo and H.A. Denmark were consulted in preparation of the episode. Learn more about twospotted spider mites at this link: http://entnemdept.ufl.edu/creatures/orn/twospotted_mite.htm

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