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/
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/
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.
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/
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.
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.
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
This week let’s time travel a little bit. Not the teeny, across the centuries travels Claire Fraser undertakes in Outlander. Nah, let’s journey back hundreds of millions of years long before T. rex walked the earth to the ancient origins of insects. In times when giant tree ferns ruled earth’s forests, primordial relatives of silverfish, the Triassomachilidae, foraged for starchy remains of plants on the verdant forest floor. Now fast forward several hundred million years to last Tuesday, when a handsome silverfish appeared at 6:10 am on the bathroom wall. With ancient decaying tree ferns conspicuously absent from my home, I wondered what delicacies silverfish discover inside a residential dwelling.
Among the most ancient of insects are the silverfish. On rare occasions I am graced by their presence early in the morning on my bathroom wall or maybe in the sink. My catch and release policy ensures they can find more natural surroundings when I release them outdoors.
Actually, we share many carbohydrate-rich food sources with plants found at the time of the world’s first silverfish. Modern food on the silverfishes’ menu include those high in starchy materials such as the cellulose found in paper goods and glue, the kind you were told not to eat in first grade, the glue that binds pages of books together. It is not surprising then, that some species of silverfish are important pests in libraries and museums where starchy materials abound. Other tasty treats for silverfish include natural fabrics such as linen, silk, and cotton, cereals, preserved meat, and dead insects, including other silverfish. Of course, in the geological time scale, frame houses are a fairly recent contrivance and typical natural habitats for silverfish are decaying logs and leaf litter, caves and crevices, and, for some species, ant nests.
The name silverfish was coined in part from the silvery scales found on the insect’s exoskeleton. The “fish” part apparently refers to the resemblance of the silverfish’s scales to those of fish. If you find silverfish scurrying around your home and wonder about the source, have a close look in dark, damp corners of the basement or other places where books or garments might be stored. Infested books or clothing can be placed in plastic bags and deposited in a freezer for a few days to kill attendant silverfish. Silverfish also thrive in conditions of high humidity and dehumidifiers placed in damp rooms may help reduce the suitability of these locations for silverfish. Removing clutter, storing books and garments in airtight containers, and vacuuming closets and storage areas will also help reduce populations of silverfish and other nuisance pests around the home. So, where is the wellspring for my silverfish? Well, just beneath my bathroom floor lies a pantry used to store paper goods and other household items. Sometimes it is a bit musty and maybe it could use a more regular visit with a vacuum. But, I have to admit, there is something remarkable about a morning greeting by a creature older than dinosaurs. I usually just catch these old timers in a paper cup, warn them to socially distance especially when predators are near, and release them in the wild.
Acknowledgements
To learn more about silverfish, please check out the fascinating fact sheet “Common name: silverfish, scientific name: Lepisma saccharina Linnaeus (Insecta: Zygentoma: Lepismatidae), Introduction – Distribution – Description – Life Stages and Biology – Hosts – Economic Importance – Survey and Detection – Management – Selected References” by Eleanor F. Phillips and Jennifer L. Gillett-Kaufman. It can be found at this link: http://entnemdept.ufl.edu/creatures/URBAN/silverfish.HTM
Next weekend we celebrate Valentine’s Day, a day named in honor of a third century Italian saint commemorated throughout the centuries by exchanging notes of love, romance, gifts of flowers and candy, and boatloads of affection. Several amorous characters take center stage in this Bug of the Week. Whether it’s a horny male Hercules beetle out for a romp on a stump, wheel bugs enjoying an intimate dinner of fall webworm caterpillars, or teenage cicadas celebrating a day in the sun after seventeen years underground, conjugal visits abound in the insect world. Let’s find out why.
For many animals, copulation is a short-term affair, measured in mere minutes or sometimes fractions thereof. However, insects depicted in this episode linger long with their mates, in some cases copulation lasts for hours and even days. Red-shouldered bugs we met in a previous episode may copulate for eleven days. How exhausting! Prolonged copulation and post-copulation “riding” of a male on the back of its mate is common in many orders of insects. By denying interlopers access to a female, prolonged mating and post-copulatory guarding by the male helps ensure that his sperm will be the ones which fertilize his mate’s eggs. In the world of insects, often the last mating before eggs are laid is the one that counts. This likely explains the oft observed pairings of so many male and female insects.
Long before Disney coined the term “Love Bug” for a rambunctious Volkswagen beetle, denizens of Florida and the Gulf states knew of another kind of lovebug. The Floridian lovebug is a small fly with a red thorax and black body and wings. The name “lovebug” derives from the fact that these small flies are often found intimately entangled. Lovebugs belong to a family called the Bibionidae. As larvae, bibionids eat decaying plant material and are important decomposers like isopods we met in a previous episode. After completing development in the soil, they pupate and emerge as adults. Adult flies do not bite or sting, but vast numbers emerge in spring and fall creating a real nuisance to residents in southern states. In addition to entering homes and bumbling about the garden, lovebugs splatter windshields of cars and trucks creating hazardous driving conditions. They become numerous enough to clog radiators of cars, causing them to overheat. One way to avoid these lovers is to drive in the late afternoon or evening when lovebugs are less likely to take wing.
Many Insects have prolonged copulation and often males guard their mates for hours or days following copulation. Just for fun, let’s look at a few. From first to last, they are: Damselflies coupled in the “heart” position for long periods of time; conjoined spur-throated grasshoppers basking in sun; camera-shy periodical cicadas that will appear by the trillions this spring when Brood X appears; peripatetic milkweed bugs playing push me, pull you; gorgeous dogbane beetles enjoying dinner and a date on their heart-stopping host; male margined carrion beetles engaging in shaky business with their mates; female thread-waisted wasps dining on pollen while their mate hitches a ride; and adorable male horn-faced mason bees fending-off suitors while guarding their betrothed.
With respect to kissing and kissing bugs, many would agree that kissing ranks right at the top when it comes to affection. However, the kiss of the kissing bug can be oh, so much more than that. Kissing bugs belong to a family of sucking insects called assassin bugs. Assassin bugs are predators, predators with long beaks which they use to suck blood from many other kinds of animals. Kissing bugs take the act of predation one step further. Their primary source of food is the blood of vertebrates, including mice, dogs, and humans. During the day, kissing bugs hide in crevices in plaster, cracks between boards, or in gaps in thatched roofs. At night, these little vampires leave their refuge and quietly seek unsuspecting humans to suck their blood. They may feed on any exposed body part, but look out, their dining preferences swing to tender tissues on people’s faces, especially the lips, hence the name kissing bugs. In southern Texas, Central and South America, kissing bugs are common. For most people the bite of the kissing bug may go unnoticed, or it may leave no more than a small red mark. But for those allergic to the saliva of kissing bugs, itchy welts, rashes, and swelling can occur. As with the introduction of any foreign protein into the body, anaphylactic reactions are a concern. A greater worry associated with kissing bugs is their ability to vector a nasty parasite called Trypanosoma cruzi, the causal agent of a sometimes fatal disease called Chagas disease. The parasite is ingested by the kissing bug as it feeds on an infected animal. Carried in the gut of the kissing bug, the parasite issues forth when the kissing bug defecates on a victim’s skin. An abrasive scratch by the victim or a small puncture in the skin allows the parasite to enter the body and wreak havoc. How disturbing! While most common in regions of Central and South America, kissing bugs can be found as far north as Pennsylvania on the east coast and California on the west coast. If your adventures take you to rural areas of Mexico, Central or South America where Chagas disease is endemic, always sleep inside your netting and remember, no kissing the kissing bugs, even if it is Valentine’s Day!
Acknowledgements
The intriguing article “The adaptive significance of mate guarding in the soapberry bug, Jadera haematoloma (Hemiptera: Rhopalidae)” by Scott P. Carroll, the great Featured Creature fact sheet “common name: lovebug scientific name: Plecia nearctica Hardy (Insecta: Diptera: Bibionidae) Introduction – Classification – Distribution – Description – Key to the Species – Dilophus sayi – Behavior – Hosts – Economic Importance – Management – Selected References” by H.A. Denmark and F.W. Mead, and the CDC Chagas disease website were consulted to prepare this episode. Bug of the Week thanks Marcia Shofner for the inspiring this heart-warming Valentine’s Day episode.
This week we turn to the Bug of the Week mailbag where we received a picture of an unusual winter-active insect found on the trunk of a tree. Let’s visit stoneflies, curious amphibious insects whose lives are split between two worlds; a life aquatic in their youth and romantic interludes on land as adults. While many insects migrate or enter a hibernal torpor called diapause during this frosty season, winter stoneflies are in their glory. Special compounds including glycerol, proteins, and sugars act like antifreeze and prevent stoneflies from freezing to death as they cavort on snow covered stream banks. These ancient insects can be found on stones, vegetation, and bridges near small, fast-moving streams. These week’s star was sighted in a nursery near a major river in western Maryland loitering on the bark of a tree.
Adult winter stoneflies are dark brown or black and are active day and night. In their youth, stoneflies live in fresh water, rushing streams and rivers. Juvenile winter stoneflies, called nymphs, graze on submerged aquatic vegetation or decaying organic matter. Other species have abandoned a vegan diet and eat aquatic insects, including other stoneflies. Stonefly nymphs obtain oxygen from the water through delicate gills lining the neck, thorax, or abdomen. Most immature insects shed their skin or molt just a few times as they develop. However, some species of stoneflies may molt more than 20 times before leaving the water as adults in search of mates. The remarkable transformation from nymph to adult transpires at the edge of the stream as the nymph emerges from the water and latches onto a stone, log, or plant. The exoskeleton splits along the midline and the adult stonefly emerges like a wraith from the cast skin. When the exoskeleton hardens, adults walk and fly to find mates. As adults, food choice differs on a species basis. Some eat lichens, algae, or vegetation, but others gain all necessary nutrients as nymphs and never feed as adults. Winter stoneflies are relatively weak fliers and seem to prefer walking and running to flying. However, other species of stoneflies are good fliers and are attracted to porch lights and, unfortunately, bug zappers.
Stonefly courtship is a curious matter. A hopeful guy stonefly strikes the surface of a resting place, such as a small branch or a stone, with its abdomen to create a specific drum beat. If a female of the same species is nearby and favorably impressed by his rhythm and sound, she will drum a reply with her abdomen. The percussive duet continues and if both like what they sense, the deal is sealed and they mate. After mating, the female stonefly will swoop to the surface of the water to deposit her eggs. This is a season of joy for fish living in stonefly laden streams. Trout, steelhead, and other freshwater fish find stonefly nymphs and adults delectable. Both adult and juvenile stoneflies are an important source of food for denizens of our streams. Fisherman have taken advantage of this passion and created a variety of lures that mimic stoneflies with colorful names like Montana Stone Yellow and Henry’s Fork Yellow Sally.
Plucked from a riverbed, a stonefly nymph dashes to return to its watery realm. Shed skins of stoneflies cling to logs and stones near riverbanks where nymphs molt and become adults. On wintry days, males roam icy landscapes and even slowly moving humans in search of mates. Male stoneflies drum their abdomen on substrates including small branches and stones along the river to attract a mate. While inaudible to the human ear, a receptive female will catch his vibe and signal her willingness to mate by returning his percussive performance with one of her own. Who says drummers aren’t romantic?
Stoneflies are also important indicators of water quality. Streams with heavy sediments, low oxygen content, or pollutants do not support a diversity or abundance of stoneflies. Stoneflies emerging from your local stream are a positive sign of a healthy environment. So, during the next couple of weeks, take a walk on a sunny afternoon and visit a small stream or river to seek the stonefly. The best viewing is when stream banks are covered with snow and stoneflies clamber from the chilly waters below. The winter stoneflies featured in this Bug of the Week were observed on warmish afternoons on a small footbridge spanning the Little Patuxent River in Columbia, Maryland, on the Billy Goat Trail along the mighty Potomac River in Maryland, near the Monocacy River in Frederick County, Maryland, and along the banks of Pidcock Creek near Lambertville, Pennsylvania.
References
Bug of the Week thanks Steve Black for sharing his great image of a winter stonefly discovered on a tree-trunk. The fascinating book “Aquatic Entomology” by W. Patrick McCafferty was used as a reference for this Bug of the Week. Here is a link to a really nice article detailing the stonefly’s clever strategies for surviving winter: https://blogs.scientificamerican.com/guest-blog/winter-stoneflies-sure-are-supercool/