A fly with a golden touch? Mydas fly, Mydas clavatus

One of my favorite mythological tales is that of King Midas, the ruler of Phrygia who wished for and was granted the power to turn everything he touched into gold. Apparently, this was his undoing as he starved to death when the food he touched turned into inedible gold – poor guy. Last week my nature- loving neighbor shared a wonderful video of majestic mydas flies cavorting around the stump of an ancient pin oak tree that once graced her yard. It seems this stump serves as a perennial home for her mydas flies. Each summer they provide entertaining performances as males battle each other and find romance with the females which, in turn, search for places to deposit their spawn in just the right spot in the decaying stump. Female mydas flies deposit eggs in rotting wood where their predaceous larvae dine on other soft bodied insects, including the grubs of scarab beetles, kin of the ones we met in previous episodes such as “Hercules Beetles.”

The star of this episode, Mydas clavatus, the clubbed mydas fly, named for its clubbed antennae, is a member of a relatively small family of very large flies whose biology remains somewhat unknown. Mydas clavatus is among the largest of all North American flies, with a body length often more than an inch. It is believed that their black–velvet coloration presents the visage of a large stinging wasp. This confers protection from enlightened predators that have learned not to mess with painful, black, stinging insects. One report holds that they also have a behavioral mimicry in which they curl their abdomen and jab at an aggressor in a mock stinging charade aimed to fool potential predators.

Decaying stumps like this one serve as a home for scarab grubs, a critical food source for mydas fly larvae. Watch as a mydas fly searches the base of the stump. Maybe it’s a female looking for just the right spot to deposit her eggs. Nearby on leaves of a holly a mydas fly does a little fly dance with its forelegs.  And on a lilac near the stump another mydas fly shows no fear of a bug geek with a camera. Video credits to Pam Gealy and Michael Raupp

Adult flies have been observed dining on the nectar and pollen of flowers of Spiraea alba, Pycnanthemum virginianum, Asclepias syriaca, A. verticillata, Monarda punctata, Teucrium canadense, Verbena hastata and Saponana officinali. In years past, they frequented by garden, attracted perhaps by the abundance of butterfly weed in my flower bed which served as a beacon for this unusual visitor.

Adult mydas flies are rather tranquil and allow bug geeks to take pictures before flying away for some unknown fly business. Unfortunately for me, the mydas fly that have visited my garden for photo ops lacked the Midas touch and the holly and pumpkin on which it perched failed to turn to gold. Still, seeing these unusual creatures always provides a golden moment for a bug geek.

References

Bug of the Week thanks Pam Gealey for sharing videos and images of her majestic mydas flies that inspired with episode. Dr. Shrewsbury captured images of the mydas fly. The delightful account “Adult female Mydas clavatus (Diptera: Mydidae) feeding on flowers in Wisconsin” by Andrew H. Williams and the interesting web page “Mydas fly” by Jeffrey K. Barnes were used as references.

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In previous episodes we visited sensational Asian giant hornets, a.k.a. murder hornets, and some of their look-alikes including European hornets and cicada killer wasps. Last week I received an inquiry about male cicada killers. A curious homeowner wondered if they were harmful to humans. This week we revisit an episode from a few years ago to learn about these amazing aerial acrobats. Sit back and relax, male cicada killers are harmless to humans but female cicada killers are lethal to annual cicadas. Female cicada killers kill cicadas as a food source for their young. During the daytime, female cicada killers hunt prey in the treetops where annual cicadas are found. Once captured and paralyzed, cicadas are interred in subterranean crypts. To see how female cicada killers roll, please check out this episode of Bug of the Week, “Cicadas beware, the ladies are in town: Female cicada killer, Sphecius speciosus”.

Although they appear fierce and perhaps even dangerous, male cicada killers pose no threat to humans or pets. Only females have a stinger, and try as he might, the male’s jaws and genitalia failed to puncture my skin. However, I have heard tales of females delivering a memorable defensive sting when inadvertently stepped on or trapped under knee or hand. Video credit: Paula Shrewsbury, UMD

But in advance of the appearance of the ladies, two male cicada killers established territories about twenty feet apart in my flower bed. So began a fierce competition for dominance of space and, I suppose, eventual access to the babes soon to emerge from the earth. Each morning shortly after sunrise as the morning sun warms the land, two feisty males arrive at their respective perches, one on a short yew bush and the other on the nozzle of my garden hose. As you will see in the video, they are on high alert, frequently leaving their perch for a short flight. Not quite understanding the thinking of the wasp mind, I imagine these forays are designed to provoke a battle with the other hopeful suitor. Occasionally, these sorties extend far enough from the perch that one male will enter the territory of the other. This results in a remarkable battle complete with frenetic buzzing and males interlocked in flight. It appears much biting and kicking goes on as evidenced by the response of a cicada killer when I captured one and held it. Eventually one breaks away and skedaddles toward my neighbor’s lawn with the victor in hot pursuit. But the victory seems fleeting. Male cicada killers either have remarkably short memories or indefatigable egos as the aftermath of these vicious mêlées soon results in both males returning to their perches only to repeat the battle a short time later.

One perched on a shrub, the other perched on my garden hose. These two fellows are pumped and looking for a tussle.  Short forays from the perch sometimes result in spectacular aerial battles as each tries to lay claim to the territory where females will soon appear.  Video credit: M. J. Raupp

Perhaps one sunny morning only one of these fierce flyers will remain and the vanquished will have departed for less ardently defended turf in search of his own mate.  But for now, with coffee in hand, this is the best early morning bug show in my garden.     

Acknowledgements

For more information about cicada killers including videos of them in action, please visit Chuck Holliday’s magnificent cicada killer website, BIOLOGY OF CICADA KILLER WASPS.

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For the better part of the last moth inquiries about spotted lanternflies have poured into my mailbox. One of the most interesting dealt with the appearance of a remarkable “albino” lanternfly spotted by an inquisitive citizen. Albinism in humans and other animals results when cells responsible for producing melanin, a pigment responsible for color of skin, hair, and eyes, fail to produce enough melanin.  While relatively common in humans and other vertebrates, albinism is rare in insects. The pale orange spotted lanternfly that inspired this story is likely a recently molted fourth instar lanternfly nymph.  Time out, what the heck does that mean? Lanternflies belong to a clan of insects called the Hemiptera. These insects have sucking mouthparts to sip plant fluids.  Their development includes three life stages, eggs, nymphs, and adults. From spotted lanternfly eggs hatch polka-dotted black and white juveniles called first instar nymphs. As they grow from one stage to the next, they shed their exoskeleton just like our more familiar blue crab. Once they shed their old skin, they are almost pure white for a while as their new skin hardens and begins to develop color. The second and third instar nymphs are also black with white spots. However, the last nymphal stage, the fourth instar nymph, is bright red with black patches and white spots when its pigmentation is complete. The picture that inspired this episode is a newly molted fourth instar nymph in the process of turning from pale orange to brilliant red.

Last May in the DMV spotted lanternfly nymphs hatched from eggs. Newly hatched lanternflies are pure white and appear to be albino, but soon they turn jet black and are speckled with white polka dots. For months they have been feeding on leaves and stems of plants in landscapes and gardens. But a few weeks ago, we began to see the beautiful fourth instar nymphs, their scarlet bodies covered with black patches and white spots. Last week reports of adult lanternflies streamed in as lanternflies landed on people and walked across windshields of cars. It won’t be long before hordes of lanternflies gather on trees, shrubs, and vines to feed.   So, get ready DMV, here come the lanternflies.   

The most frequently asked question in the Bug of the Week mailbag over the past two weeks is why are we seeing so many spotted lanternflies? At least three reasons help us understand why this is the case. First, let’s go back a decade or so to spotted lanternflies’ original detection in Berks County, PA.  In the intervening decade, spotted lanternflies have established and are reproducing in more than fifteen states. They have spread more than 600 miles away from ground zero in Berks County. More people are encountering lanternflies simply because they now occupy a much larger geographic area in the US. Here in the DMV we have gone from a few infested counties in Maryland and Virginia in 2018, to more than 60 infested counties. Yes, folks lanternflies are also in the District of Columbia.

Second, as lanternflies spread either by natural means or with assistance from humans, new colonies are established. These new infestations often are founded by an egg mass or two, each with 30 to 60 eggs, that hitched a ride on lawn furniture, a camper, or maybe a metal sculpture. For several years these pioneers might be off the radar, undetected, as was the case with the initial introduction of spotted lanternflies in Pennsylvania. With abundant food sources like the invasive tree of heaven and other delectable plants and low levels of predators, parasites, and pathogens tracking their burgeoning populations, lanternflies can enjoy a period of exponential growth. As satellite colonies merge along the ever-expanding lanternfly front and as populations expand in the generally infested area, more people encounter spotted lanternflies.  

Third, size matters. Bigger insects are more commonly noticed than smaller ones. Tiny lanternfly nymphs hatching from an egg are but a few millimeters long. They scuttle about vegetation on the forest floor and low-lying shrubs feeding on more than 100 plant species. However, by July, brilliant red nymphs have molted into tawny coated adults an inch or more in length. Being more than 20 times larger than their youngsters, adults are more readily noticed as they cluster on the trunks of trees or take flight and move about the landscape in search of food, mates, and places to deposit eggs. In reality, due to the high mortality of juveniles which is the hallmark of most insect species, there are far fewer lanternflies now than there were back in May when eggs first hatched. I’ll bet you are finding little or no solace in this.

You think Superman is faster than a speeding bullet? Just watch this lanternfly nymph jet away from the nosy camera. Watch again at one twentieth of normal speed. That’s one speedy bug.  

What’s next for spotted lanternfly here in the DMV? Hordes of adult lanternflies and their attendant deluge of honeydew soon will coat vegetation underlying lanternfly infested trees. Honeydew is a substrate for the growth of sooty mold, a non-pathogenic mold that cloaks leaves and stems of plants, reducing the ability of plants to capture the energy of sunlight and conduct photosynthesis. More disturbing will be the arrival of sugar junkies, hordes of wasps and bees intent on enjoying the carbohydrate bounty.   

Is there any good news here? As we learned last autumn, scientists at Penn State documented more than 1000 attacks by spiders, mantises, birds, and other predators of spotted lanternflies. Also getting in on the act are naturally occurring soil fungi that have caused at least one lanternfly population to collapse in Pennsylvania. In addition, spotted lanternflies are reported to kill one of their favorite sources of food, invasive tree of heaven. Here’s hoping Mother Nature continues to send help in mitigating the invasion of spotted lanternflies.          

For more information on the biology and management of spotted lanternfly click here.

Acknowledgements

Thanks to James Murdock for providing inspiration for this episode. Thanks also to Eloise and Abby Kollins and Paula Shrewsbury for wrangling and spotting spotted lanternflies. Wonderful resources provided by scientists at Penn State University and Cornell University were consulted to prepare this episode. The fascinating article “A pair of native fungal pathogens drives decline of a new invasive herbivore” by Eric H. Clifton, Louela A. Castrillo, Andrii Gryganskyi, and Ann E. Hajek was used as a reference for this episode.

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From the Bug of the Week mailbag: What happens when a wheel bug goes for a spin? Wheel bug, Arilus cristatus

In previous episodes we met one of the toughest customers in Mother Nature’s gang of beneficial insects, the wheel bug. Wheel bugs play an important role reducing populations of noxious invasive pests like brown marmorated stink bugs and they also dine on important forest pests including fall webworms and other native caterpillars. This week we received the following message about a wheel bug that thought it might be fun to take a spin in a rotating core in a paper mill. Here’s the message. “I just thought you would be interested to know that this bug crawled inside of a core with a diameter of 4.41inches and this core went in our winder. He was rotated at 8000fpm for about 150 seconds start to finish and survived. Looks like he was a little dizzy but he ended up crawling out and then flying towards our control panel. So we determined he deserved to live so we caught him in a bag and took him outside. Crazy the endurance and survivability on this thing!!!” 

I am not exactly sure how far this predator spun around, but at 8000 feet per minute for 2.5 minutes seem like it might have traveled some 20,000 feet in circles. I don’t know about you, but I’d be dizzy, if I survived.

Wheel bugs are fierce generalist predators. Watch as this female stalks a dagger moth caterpillar. She slowly circles to the head of the caterpillar to deliver a lethal jab with her strong beak. After sizing up the prey with her left foreleg and extending her beak, she makes a lightning-fast strike to capture her prey. Forest pests like fall webworm caterpillars are also on the menu. This female snares a webworm while on a romantic interlude with her mate. Wheel bugs regularly dine on other pests including brown marmorated stink bugs. With other members of Mother Nature’s hit squad, they contribute to the decline of stink bugs in many parts of the country.  

To round out this episode, here is a little more about wheel bugs and how they roll when not in a paper mill. The wheel bug is a species of assassin bug and, as the name implies, it kills other insects. The common name, wheel bug, stems from the fact that this terror has a structure on its back that looks like a spoke-bearing medieval torture device. The function of this wheel is known only to Mother Nature and the bug, but not to me. The business end of the wheel bug is the powerful beak or proboscis stored between the beast’s front legs when it is not in use. Upon spying a tasty morsel, the wheel bug cautiously approaches, embraces the mark with long front legs, and impales the victim with the powerful beak. The wheel bug pumps strong digestive enzymes through the beak into the prey. These enzymes liquefy the body tissues of the hapless victim. A muscular pump in the head of the bug slurps the liquefied meal up through the beak. Young wheel bugs use protein from their prey for growth and development and adult females convert prey into eggs. In autumn, the well-fed female wheel bug lays barrel-shaped eggs in clusters of several to more than one hundred usually on the bark of a tree. Eggs hatch the following spring in May and June.  Small wheel bugs, called nymphs, are magnificent creatures with bright red abdomens and orange antennae. They dine on a wide variety of insects including caterpillars, sawfly larvae, beetles, and other bugs. In most years, I feel lucky if I witness a half dozen of these monsters at work in the wild. With plant nurseries and landscapes laden with invasive pests like stink bugs and spotted lanternflies, it is not unusual to see scores of wheel bugs stealthily stalking and assassinating their stinky marmorated cousins and other invaders. How much benefit results from greater numbers of these assassins remains to be seen, but we hope that these bugs and other naturally occurring predators and parasites will help stem the onslaught of brown marmorated stink bugs, spotted lanternflies, and other invasive species. If you encounter wheel bugs, please heed this caution. While holding and admiring a wheel bug, I learned firsthand, so to speak, that the wheel bug could deliver a memorable, painful poke with its beak. If you keep wheel bugs as pets beware, try not to handle them directly or you too may become an unwitting victim of this clever assassin.

Acknowledgement

We thank Joshua Colgin for providing images and the fascinating story that inspired this episode.

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From the Bug of the Week mailbag: What happens when a wheel bug goes for a spin? Wheel bug, Arilus cristatus

In previous episodes we met one of the toughest customers in Mother Nature’s gang of beneficial insects, the wheel bug. Wheel bugs play an important role reducing populations of noxious invasive pests like brown marmorated stink bugs and they also dine on important forest pests including fall webworms and other native caterpillars. This week we received the following message about a wheel bug that thought it might be fun to take a spin in a rotating core in a paper mill. Here’s the message. “I just thought you would be interested to know that this bug crawled inside of a core with a diameter of 4.41inches and this core went in our winder. He was rotated at 8000fpm for about 150 seconds start to finish and survived. Looks like he was a little dizzy but he ended up crawling out and then flying towards our control panel. So we determined he deserved to live so we caught him in a bag and took him outside. Crazy the endurance and survivability on this thing!!!” 

I am not exactly sure how far this predator spun around, but at 8000 feet per minute for 2.5 minutes seem like it might have traveled some 20,000 feet in circles. I don’t know about you, but I’d be dizzy, if I survived.

Wheel bugs are fierce generalist predators. Watch as this female stalks a dagger moth caterpillar. She slowly circles to the head of the caterpillar to deliver a lethal jab with her strong beak. After sizing up the prey with her left foreleg and extending her beak, she makes a lightning-fast strike to capture her prey. Forest pests like fall webworm caterpillars are also on the menu. This female snares a webworm while on a romantic interlude with her mate. Wheel bugs regularly dine on other pests including brown marmorated stink bugs. With other members of Mother Nature’s hit squad, they contribute to the decline of stink bugs in many parts of the country.  

To round out this episode, here is a little more about wheel bugs and how they roll when not in a paper mill. The wheel bug is a species of assassin bug and, as the name implies, it kills other insects. The common name, wheel bug, stems from the fact that this terror has a structure on its back that looks like a spoke-bearing medieval torture device. The function of this wheel is known only to Mother Nature and the bug, but not to me. The business end of the wheel bug is the powerful beak or proboscis stored between the beast’s front legs when it is not in use. Upon spying a tasty morsel, the wheel bug cautiously approaches, embraces the mark with long front legs, and impales the victim with the powerful beak. The wheel bug pumps strong digestive enzymes through the beak into the prey. These enzymes liquefy the body tissues of the hapless victim. A muscular pump in the head of the bug slurps the liquefied meal up through the beak. Young wheel bugs use protein from their prey for growth and development and adult females convert prey into eggs. In autumn, the well-fed female wheel bug lays barrel-shaped eggs in clusters of several to more than one hundred usually on the bark of a tree. Eggs hatch the following spring in May and June.  Small wheel bugs, called nymphs, are magnificent creatures with bright red abdomens and orange antennae. They dine on a wide variety of insects including caterpillars, sawfly larvae, beetles, and other bugs. In most years, I feel lucky if I witness a half dozen of these monsters at work in the wild. With plant nurseries and landscapes laden with invasive pests like stink bugs and spotted lanternflies, it is not unusual to see scores of wheel bugs stealthily stalking and assassinating their stinky marmorated cousins and other invaders. How much benefit results from greater numbers of these assassins remains to be seen, but we hope that these bugs and other naturally occurring predators and parasites will help stem the onslaught of brown marmorated stink bugs, spotted lanternflies, and other invasive species. If you encounter wheel bugs, please heed this caution. While holding and admiring a wheel bug, I learned firsthand, so to speak, that the wheel bug could deliver a memorable, painful poke with its beak. If you keep wheel bugs as pets beware, try not to handle them directly or you too may become an unwitting victim of this clever assassin.

Acknowledgement

We thank Joshua Colgin for providing images and the fascinating story that inspired this episode.

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In previous episodes we visited delightful mason bees as they made an early debut and foraged for nectar and pollen to provision their nests inside cardboard tubes and galleried firewood in a mason bee colony. Tiny bee larvae will spend the next several months completing development before pupating in their chambers come fall, but right now all is not well in the realm of mason bees. Enemies are afoot. For the past several weeks, gangs of noisy yellow and black insects, leucospid wasps, have been carefully inspecting the modular condominiums of my mason bee colony. Leucospids are generally considered rare insects, but each year the tubular homes and woody tunnels housing mason bees attract scads of these parasites.

My mason bee condominium of cardboard tubes and galleries in wood provides homes for hundreds of mason bees to raise their young. But as spring turns to summer, danger arrives. Bee babies are hunted by clever leucospid wasps. With antennae tapping, a female leucospid wasp searches a mason bee log for clues to locate potential victims within. Once the bee larvae are located, she unsheathes the ovipositor and drills into the log to lay her eggs. In slow motion, watch as she unfolds her ovipositor and pirouettes on tip toes to drill into the wood. After depositing her eggs in the brood chamber, she pulls her ovipositor out and prepares to locate the next victim.  

Leucospids are rather unique in the wasp world. Unlike most of their kin with rear-facing or under-slung egg-laying tubes called ovipositors, leucospids carry their ovipositor arched up and over their back. The small yellow and black wasps move back and forth across the surface of the mason bee’s tubes and wooden lodgings tapping gently with their antennae and drumming with their abdomen. This behavior has been noted in other species of leucospids and is likely how the female wasp evaluates where the bee larvae reside and, perhaps, the suitability of the mason bees as a meal for her young. If the female leucospid likes what she finds, she uses her remarkable ovipositor to penetrate the cardboard tubes or my tough oak logs. She deposits eggs inside the cells of the developing mason bees. It is fascinating to watch the female wasps insert her ovipositor into mason bee galleries in search of bee larvae to serve as food for her young. After a few days, the wasp’s eggs hatch into voracious larvae that feed as ectoparasites attached to the outside of the bee larvae. Larvae of the parasitic wasps complete development and emerge as adults to find a mate and search for more victims.

I pondered the peril of my mason bee colony and soon realized that many of my hard-working bees would be spared from the treacherous leucospid wasp. When it comes to attacking bee larvae hidden in tubes, size does matter. The ovipositor of the leucospid wasp is only long enough to penetrate the outermost tubes of my modular mason bee condominium. Likewise, holes drilled in the center of my mason bee logs will remain unscathed. The vast majority of mason bees sheltered therein are well beyond the reach of leucospid’s dangerous egg-laying appendage. While some mason bee aficionados might cover their bee condominiums with netting to prevent parasitism, I let nature take its course. Rare leucospids are magnificent in their own way and part of the circle of life in the realm of insects.  

References

Two interesting articles, “Parasitic Behavior of Leucospis cayennensis Westwood (Hymenoptera: Leucospidae) and Rates of Parasitism in Populations of Centris (Heterocentris) analis (Fabricius) (Hymenoptera: Apidae: Centridini)” by Ana Lúcia Gazola and Carlos Alberto Garófalo, and “Osmia ribifloris, a Native Bee Species Developed as a Commercially Managed Pollinator of Highbush Blueberry (Hymenoptera:Megachilidae)” by P. F. Torchio, were used as references for this episode.

 

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How can you not love Greek mythology? Polyphemus, a terrible, one-eyed giant that enjoyed feasting on men, notably Odysseus and his crew. Fitting that to escape from the cave of Polyphemus, the crew blinded him with a spear and snuck out of the cave with a herd of sheep. Giants also populate the world of insects. Polyphemus is the name given to one of our largest moths that has not one eye, but four on its dorsal wings. These are not true eyes like the compound eyes on the head of the Polyphemus moth. These false eyes or eyespots are an evolutionary masterpiece created by hundreds of colored scales arranged in patterns resembling the eye of another animal like a bird, mammal, or snake.

This montage begins with a very pregnant female Polyphemus moth that decided to lay her eggs on a lawn chair. Hopefully, the caterpillars made their way to an oak or maple tree like this one. Here is what this giant silk moth caterpillar looks like as it ascends the tree. Watch as smaller and larger caterpillars munch on one of their favorite foods, the leaves of oaks. One kind human found this female Polyphemus marooned inside a parking garage after a storm. With a little assistance, this magnificent moth took flight. Here’s looking at you Polyphemus.  Video and image credit: Nancy Koran, Peihan Orestes, and Jenny Milward.

Several species of insects employ clever patterns of coloration resembling eyes on parts of their body where eyes really do not occur. For example, in a previous episode of Bug of the Week, we met the larva of the swallowtail butterfly adorned with two sinister eyespots on its thorax. These false eyes helped create the illusion of a serpent for a larva that is really a tasty caterpillar. Scientists believe that these eyespots aid in defense of insects and other animals in several ways. Eyespots may resemble the eyes of a potential predator’s own predators. Moths and butterflies are tasty fare for many birds, but in turn, birds are meals for larger winged predators such as owls. Eyespots and color patterns on the wings of some moths resemble the face of an owl. Imagine the terror of a bird about to eat what appears to be a harmless moth, when suddenly the hungry bird confronts the face of an owl. A second way that eyespots may aid in defense is to direct an attack away from vulnerable parts of the body. Some predators attack the head of the victim where maximum damage results. False eyespots on less critical parts of the body such as wings may steer a first strike away from a lethal spot and provide time for the intended prey to escape.

Last week, I received images of a very pregnant female Polyphemus moth that had settled on a patio and proceeded to lay batches of eggs on a lawn chair. I know not what became of the eggs or the moth, but with luck the eggs hatched and the tiny caterpillars, which don’t eat lawn chairs, found their way to sustaining leaves of elm, oak, walnut, or more than a dozen other woody trees and shrubs. These marvelous caterpillars will gain more than a thousand times their birth weight before they spin cocoons of leaves and silk and change into pupae. With luck, in a few weeks, we will have dozens of four-eyed moths returning to the wild to scare the daylight out of would-be predators.     

Acknowledgement Special thanks to Nancy Koran for providing inspiration and images for this episode. Cool camera work by Peihan Orestes and Jenny Milward helped create this story. The fantastic Caterpillars of Eastern North America by David Wagner was used as a reference.      

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Last week we met voracious flower fly larvae as they ravaged populations of brown ambrosia aphids on my silphium cup plant. This week things have gone from bad to worse for the pesky aphids as populations of sneaky predatory aphid midges arrived in force and rained carnage on the aphids. In past episodes, we visited many wild predators like firefly larvae, tiger beetles, and spiders that employed powerful jaws or fangs to slice, dice, and consume hapless prey. Today we meet a predaceous midge, Aphidoletes aphidomyza, with a fondness for the legs of aphids. Hold on, a fondness for legs, what’s that about? Here’s the story. Larvae of predaceous midges are many times smaller than those of the large flower flies we met last week. In fact, they are much tinier than the aphids on which they feast. These diminutive predators sneak up on the victims and with persistence and luck, they attach themselves to the joints on the aphid’s leg. After they are plugged in, they inject paralytic venom, likely produced in their salivary glands, into the blood stream of the aphid. In a matter of minutes, the paralytic action of the venom takes hold immobilizing the aphid. As I watched one of these attacks, I saw a small midge larvae intermittently strike and bite  the left foreleg of a small aphid. As the movements of the aphid subsided, the midge slowly slithered beneath the aphid and attached itself to the right hind leg of the moribund aphid. Half an hour later the midge moved to the left hind leg. With its victim motionless, the predator finally settled on rump of aphid for its meal. After subduing their victims, midge larvae may move to meatier parts of the aphid’s body such as the thorax where they may be joined by other larvae.  Some accounts report that these tiny assassins will kill more aphids than they consume. Not sure how to explain that. The aftermath of the midge’s carnage is blackened hulks of shrunken exsanguinated aphids. 

Aphids dance away from a predaceous midge larva searching for a victim. This one snared the left foreleg of a small aphid and is injecting paralytic venom. Next it moves to the right hind leg of the moribund aphid. Then on to the left hind leg. With the aphid motionless, the larvae settles on ‘rump of aphid’ for dinner. Nearby, two midge larvae feed on the head of an aphid. When these tiny monsters are done, all that remains of the aphid colony are shriveled black carcasses.

These brown ambrosia aphids are not entirely defenseless. Watch as one drop kicks a predatory midge right off a leaf. Here’s the instant replay at one tenth normal speed.

In the killing field of Aphidoletes aphidomyza after the feast, all that remains are black shriveled carcasses of aphids. Photo by Mike Raupp

If you are feeling a bit sorry for the poor aphids in all of this, I understand. Their demise seems gruesome, meeting death by mouth hooks and venom producing flies. But remember that aphids are major pests of our crops and landscape plants causing billions of dollars of loss worldwide. Predaceous midges are key players in mitigating losses to pests in natural and managed ecosystems. They are produced commercially and regularly used in greenhouses as biological control agents for aphids.  To learn more about   Aphidoletes as biological control agents, please click on the links below.

https://biocontrol.entomology.cornell.edu/predators/Aphidoletes.php

https://ipm.ucanr.edu/natural-enemies/aphid-midge/#gsc.tab=0

Acknowledgements: Bug of the Week thanks Dr. Shrewsbury for spotting predaceous midges in the aphid outbreak on the cup plant. The informative articles “Entomo-venomics: The evolution, biology and biochemistry of insect venoms” by Andrew Walker, Samuel D. Robinson, David K. Yeates, Jiayi Jin, Kate Baumann, James Dobson, Bryan G. Fry and Glenn F. King and “Aphid Predatory Midge” by Jim Walgenbach were used as references for this episode.

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One of the best performers in my flower bed is a raucous native plant known as cup plant, Silphium perfoliatum, a premier attractor of insects to the garden. Extravagant floral displays provide nectar and pollen to wide variety of flies, bees, butterflies, and wasps. Nutrients coursing through vascular vessels support several species of sucking insects including leafhoppers, treehoppers , and aphids. And where there are abundant juicy prey items, there are predators, lots of them. During spring and early summer, populations of brown ambrosia aphids have exploded on my cup plants. Like many of their kin, in spring and summer these gals are parthenogenic. They are an all-female society reproducing without the assistance of males. As aphids feed, they excrete a waste product called honeydew. Honeydew contains volatile organic compounds (VOCs), the aromas of which act like a dinner bell ringing “come and get it”. The more aphids and honeydew on a plant, the more likely it will be discovered by flower flies. Once the infestation is detected, the females fly lays a small white egg near the colony of aphids. The egg hatches into a wriggling larva (a.k.a. maggot) whose sole purpose is to hunt and eat soft-bodied prey. With no true eyes, this blind assassin discovers its victims by swinging its head to and fro, searching for prey with sensory structures located on the front end of its fleshy head. When it bumps into an aphid, the flower fly larva snares the aphid with its mouth hook [it looks like Captain Hook’s hook]. Mouthparts pierce the aphid’s cuticle, and the larva sucks the aphid’s blood.

When in bloom, cup plants are dynamite attractors of pollinators.  But pre-bloom, cup plants often generate fantastic populations of brown ambrosia aphids. Volatile odors released by the aphids serve as a dinner bell for squads of hungry predators and parasitoids. Not long after aphid populations exploded, adult flower flies deposited eggs near colonies of aphids. From these eggs hatched fierce larvae laser focused on hunting and eating aphids night and day.  Watch as one of these tiny terrors makes short work of a misguided aphid. The flower fly larva snares the aphid with its mouth hook. It looks like Captain Hook’s hook. It then pierces the aphid and sucks out its blood. Flower fly larvae make short work of aphids on plants. Along with gangs of spiders, lady beetles, lacewing larvae, predaceous midge larvae and parasitic wasps, aphids on my cup plants will soon be history.

It’s easy to see why another name for the flower fly is hover fly. Flower flies deposit white eggs like these near colonies of aphids. Eggs hatch and blind flower fly larvae hunt by casting their head two and fro. Prey like this aphid are snagged with a mouth hook. Once captured the contents of the aphid are consumed. Sometimes hapless aphids blunder into fly larvae. You can see the dorsal heart of the larva beating as it feeds.  Little wonder that aphid populations can collapse when flower flies and other predators and parasites arrive.  

Flower fly maggots have prodigious appetites. In the laboratory, I have watched these predators consume more than 25 aphids in a day. Reports of aphid carnage in the literature puts the casualty figures at more than 200 aphids during development for each maggot. In some agricultural systems, flower flies are believed to provide 75% to 100% control of aphids. In my experience with aphids, flower flies, with a little help from lady beetles and other predators, can entirely wipe out populations of aphids in a matter of weeks. So, before you reach for the aphid spray, carefully look to see if the maggot brigade and company are at work. While the brown ambrosia aphids put a minor beat down on my cup plants, they are generally good news for my garden. The aphids have become a factory for many species of predators including spiders, lady beetles, lacewing larvae, predaceous midges and parasitic wasps that will move to other plants in my landscape once the brown ambrosia aphids are kaput, all part of Mother Nature’s plan for a more sustainable landscape. 

Acknowledgements

We thank Dr. Jeff Shultz for identifying the cool male lynx spider and Dr. Paula Shrewsbury for planting silphium, identifying the pretty polished lady beetle and providing inspiration for this episode.  The fascinating account of defensive behaviors in aphids entitled “Collective Defense of Aphis nerii and Uroleucon hypochoeridis (Homoptera, Aphididae) against Natural Enemies” by Manfred Hartbauer was consulted to prepare this episode.

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Happy 20 years Bug of the Week

This June marks the celebration of 20 years of Bug of the Week. We want to thank all our viewers in more than 200 countries worldwide for your continued support. Last year we set a record with more than 370 thousand visits. Thank you so much. This week we call on one of Mother Nature’s most fabulous creations to help us celebrate. Three cheers for fireflies.

Much of this episode comes courtesy of Dr. Paula Shrewsbury, Entomologist at the University of Maryland, College Park, who created this great article for her “Beneficial of the Week” in the IPM Alerts – Landscape & Nursery.

“I saw my first fireflies of the season in Sharpsburg, MD on May 17th; and this week I saw fireflies flashing in Columbia, MD. It looks like it is going to be another good year for fireflies based on the amazing display of flashing lights so far.

Fireflies, also known as lightening bugs, are really neither bugs nor flies. They are characterized as soft-winged beetles in the order Coleoptera and the family Lampyridae. There are over 2,200 known species of fireflies, of which about 165 species have been reported in the U.S. and Canada. Fireflies are found in temperate and tropical regions and in the humid regions of the Americas, Asia, and Europe. In the U.S., the abundance of fireflies is greater east of the Great Plains than in western states. Interestingly, fireflies that produce light are uncommon in western North America. Some firefly species are diurnal, and therefor have no need to create light. These species are known as daytime dark fireflies and they use chemical pheromones for mate attraction. Although the adults do not light, the larvae do glow at night, similar to eastern species.

Most flashing species occur east of the Mississippi River, are about ¾” in length and are active at dusk and night. Adults and larvae of many firefly species exhibit bioluminescence – they glow in the dark! Many organisms such as bacteria, fungi, jellyfish, algae, fish, clams, snails, crustaceans, and of course insects [including some click beetles] exhibit bioluminescence. Firefly species have special light organs that make the underside of their abdomens light up.

To help celebrate twenty years of Bug of the Week, let’s enjoy one of Mother Nature’s finest light shows courtesy of fireflies. How do they produce light? See the white segments at the tip of the firefly’s abdomen. These segments contain photocytes, cells that produce light. I asked this little guy to show off his stuff. Look at him go. Don’t worry, he was released nonplused but unharmed. Male fireflies perform aerial displays to impress females watching from vegetation on the ground or on branches. If the she firefly likes the performance, she may signal back with her flash. Watch as a male firefly searches for his mate on a cluster of leaves. Eventually he finds her and their union is consummated. During June and July, take a moment at twilight to visit a lawn, meadow, or park to enjoy these beautiful and illuminating creatures.

 How do fireflies make light? The light emitted by a firefly is actually a chemical reaction in the beetle’s abdomen. The light organ has special cells that contain a chemical called luciferin. An enzyme called luciferase combines oxygen with luciferin in these cells to create light. Scientists actually do not know how fireflies regulate their lights to turn them on and off. You might have also noticed how “cold” the light looks. This is because no infrared (or heat) or ultraviolet frequencies of light are emitted. Among the light-producing fireflies, lights are yellow, green, or pale red.

 Why do fireflies bioluminescence? The purpose of this bioluminescence varies. It is believed that the flashes are part of a signaling system for attracting mates. Both males and females emit light intermittently or in specific flash patterns. The rhythmic flash patterns produced are specific for each species of firefly and vary by sex within a species. The flashes that we see are from the males that are attempting to attract a mate. For example, males of the common eastern firefly (Photinus pyralis) flash every six seconds. Females watch the light “show” and if a display from a specific male is particularly attractive, she will flash a response but only if it is from the male of the same species. The male descends to that location to mate with her. In addition to transferring sperm to the female during copulation, the male offers a nuptial gift of rich protein, which the female uses to provision the eggs that will soon start to develop in her ovaries. Interestingly, in one species of firefly, Photuris pensylvanica, the female mimics the flash pattern of another species, Photinis pyralis, to attract the male of the other species to her. When the male of the other species arrives thinking, he has found his mate – she eats it to obtain defensive compounds used to protect her eggs. A bad surprise for that male.

Why are fireflies considered beneficials? Well, the soil active firefly larvae or glow worms are voracious predators of soft-bodied invertebrates and known to feed on slugs, snails, worms, and other soil-dwelling insects. Glow worms use their mandibles to inject prey with a paralyzing neurotoxin, making it defenseless, and then secrete digestive enzymes that liquify the prey making it easier to consume. Firefly larvae or glow-worms are believed to glow as a warning signal telling predators not to eat them as they are mildly toxic and taste nasty. It is not well known what all adult fireflies feed on but some feed on pollen and nectar and some are reported not to feed at all.

Although the larvae of fireflies are referred to as glow-worms, technically this is not quite correct. Glow-worms are a type of firefly where the adult female is flightless and maintains the appearance of a larva and she emits a long-lasting glow, similar to larvae. The males have the appearance of an adult firefly. To make it more confusing, other insect larvae that glow, are sometimes called glow-worms too. Since most fireflies that produce light are in the Eastern U.S., it makes the nightly light shows we encounter here something special to behold for a few weeks during spring and early summer. Be sure to help young people you know, and others, enjoy the experience of observing and collecting fireflies. Be certain to release the little lights when you are done!”

Light pollution and fireflies

Over the past few years, many have been concerned about dwindling numbers of lightning bugs in our region. While hard data on this issue are difficult to come by, one important study conducted by scientists at the University of Virginia suggests that light pollution caused by brightly lit homes and buildings has disrupted the normal ecology and behavior of these remarkable creatures. By adding artificial light to nocturnal courting grounds, normal courtship behaviors and mating success of fireflies were compromised. The authors suggest these reductions in mating success could lead to fewer fireflies in locations with light pollution. The development of natural areas and destruction of habitat are also thought to contribute to reductions in firefly populations. Others believe that widespread use of residual insecticides to treat lawns may have contributed to the lightning bug’s decline. Perhaps unfavorable weather cycles or a dearth of food for predatory lightning bug larvae, which live on the ground, may have suppressed their numbers in years past.

 

What can be done to help our fireflies and other nocturnal insects? Reducing sources of artificial light at night (ALAN) by using motion detectors to trigger security lights, timers and dimmers to regulate intensity and timing of illumination and simply turning off unnecessary lights can help. Outdoor lighting along pathways can be shielded from above to reduce light scattering that might attract flying insects. To learn more about light pollution and some solutions to ALAN, visit DarkSky.  

During these glorious days of June and July, take a moment at twilight to visit a lawn, meadow, or park to enjoy these beautiful and illuminating creatures.  

 

Acknowledgement

Bug of the Week thanks all our viewers over the last two decades. Our F2s, Eloise, Abby, and Jackie provided the inspiration for this episode and Dr. Shrewsbury provided much of the cool content. The interesting articles “Experimental tests of light-pollution: Impacts on nocturnal insect courtship and dispersal” by Drs. Aerial Firebaugh and Kyle Haynes, “Flash Signal Evolution, Mate Choice, and Predation in Fireflies” by Sara M. Lewis and Christopher K. Cratsley, “Silent Earth” by David Goulson, and fascinating studies of Dr. Sara Lewis and Dr. Thomas Eisner and their colleagues, served as resources for this Bug of the Week.

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