There will be blood: Northern House Mosquito, Culex pipiens, and friends

A week or so ago, a friend asked if mosquitoes would be biting soon. I shared with her that, the week before last, my wife smashed the vanguard of home invading mosquitoes on the bathroom wall. Apparently, biting time is just around the corner. For the last two weeks on an almost daily basis, I have been watching an upside-down garbage pail lid full of leaves and water for the signs of breeding mosquitoes. Last Wednesday my search was rewarded when I discovered several Culex egg rafts and hundreds of tiny mosquito larvae swimming in the human-made mosquito nursery. With temperatures on the rise and showers predicted, blood thirsty female mosquitoes are not far behind. Taking a line from Paul Thomas Anderson’s classic film, “there will be blood”.  

Watch as a female Culex pipiens form molestus extracts all the blood she needs to produce the next batch of eggs and then scurries away to the shadow of a knuckle to hide. Filmed at twice life speed.   

During the first several days of adulthood, both male and female mosquitoes consume carbohydrate rich food such as plant nectar or aphid honeydew. For male mosquitoes, sweets remain the sole source of food, but the gal has a blood lust. Female mosquitoes use animal blood as the source of protein to produce eggs. The pregnant mosquito lays her spawn in a water-filled container such as a pail or bird bath or in pools of standing water on the ground. Some, like the ferocious Asian Tiger mosquito, Aedes albopictus, lay eggs near the water line of a container. When the vessel fills with rainwater, eggs hatch and larval development begins. Others, such as the Northern house mosquito, Culex pipiens, lay eggs in clusters called rafts that float on the surface of the water. Each raft can contain more than 150 eggs.  

A garbage pail lid full of water becomes the perfect nursery for a crop of Culex mosquitoes. Two egg rafts contain scores of eggs ready to hatch. Nearby, fleets of mosquito larvae called wrigglers filter tiny particles of food from the water. In just a few short weeks, this lid will be bustling with fully developed wrigglers suspended beneath the water by breathing siphons. Amidst the milieu, zany mosquito pupae called tumblers bumble about. With warm temperatures predicted, adults will emerge, and yes, there will be blood.  

Mosquitoes are more than just a nuisance and several species carry important diseases such as West Nile Virus. West Nile Virus has killed more than 2,600 people in the United States since it was first detected in New York in 1999. While most of us shrug off West Nile virus if we are exposed, it can be severe and lethal to seniors and certain others. Recent research helps explain why this may be so. Our immune system plays a vital role in preventing diseases carried by mosquitoes. Cells lining our skin and mucus membranes bear specialized virus-sensing proteins called Toll-Like Receptors, a.k.a. TLRs. TLRs have the critical function of detecting invaders like West Nile virus. If TLRs detect the West Nile virus, they release additional proteins that stimulate production of chemical communication compounds called interleukins. Interleukins released into the bloodstream marshal cellular assassins called macrophages and direct them to hunt and kill cells infected with West Nile virus before the virus can multiple and make us seriously ill. Researchers have suggested that some seniors and people with compromised immune systems may lack sufficient TLRs and related immune system proteins to thwart the West Nile virus.  

Many species of mosquitoes prefer to feed at dusk and you can avoid being bitten by staying indoors in the evening. Unlike many of our native mosquitoes, the exotic Asian Tiger is a daytime biter, adding hours of entertaining itching, scratching, and swatting to days in the garden. Protect yourself from aggressive biters by wearing light-weight, long-sleeved shirts and pants when working outdoors. Certain brands of clothing are pretreated with mosquito repellents such as permethrin. I have worn these in tropical rainforests where mosquitoes were ferocious and they really did help. Many topical insect repellents can be applied to exposed skin before you go outdoors. Some will provide many hours of protection, while others provide virtually none. Some repellents should not be applied to children and you should always help kids apply repellents. Do not apply repellents containing DEET under clothing. To learn more about mosquito repellents, click this link to see repellents recommended by the Centers for Disease Control.  

For safety, be sure to read and follow the directions on the label of the repellent before you apply it to people or clothing. If you dine outdoors, place a small fan on your patio. The light breeze created by the fan will greatly reduce the number of mosquitoes flying and biting. Many traps are also available to capture and kill mosquitoes. Some rely on a light source to attract blood seekers. Many types of moths, flies, and beetles are attracted to light, however, mosquitoes unfortunately do not use light to find their meals and are not readily attracted to light traps. One study demonstrated that less than 1% of the insects attracted to light traps were biting flies such as mosquitoes. This study estimated that light traps kill billions of harmless and beneficial insects each year. Actually, blood seeking mosquitoes are attracted to odors emanating from the host. As we move about the earth, we release many odors including carbon dioxide and lactic acid that are used by hungry mosquitoes to find us. Some mosquito traps release carbon dioxide and will catch many mosquitoes. Female mosquitoes ready to lay eggs are attracted to odors emanating from water sources. A clever trap called a Gravid Aedes Trap (GAT) has been used in community-wide programs in the DMV to reduce local populations of Asian Tiger mosquitoes. Females fly into these traps to lay eggs but never escape. Sounds like Hotel California for these tiny vampires.  

To reduce the chances of mosquitoes breeding around your home, eliminate standing water by cleaning your gutters, dumping your bird bath twice a week, inverting your wheelbarrow and getting rid of water filled containers. If you have an aquatic water garden or standing water on your property that breed mosquitoes, you can use a product containing the naturally occurring soil microbe known as Bacillus thuringiensis israelensis, aka Bti. Bti comes formulated in doughnut-shaped tablets that can be placed in water to kill mosquito larvae.  

Battalions of biters are about to make their presence known. Snap to it and get rid of those breeding sites. Get ready to protect yourself or to give blood.  

Acknowledgements

 Several interesting articles, including “How the body rubs out West Nile virus” by  Nathan Seppa, “Toll-like Receptor 7 Mitigates Lethal West Nile Encephalitis via Interleukin 23-Dependent Immune Cell Infiltration and Homing” by Terrence Town, Fengwei Bai, Tian Wang, Amber T. Kaplan, Feng Qian, Ruth R. Montgomery, John F. Anderson, Richard A. Flavell, and Erol Fikrig, “Density and diversity of non-target insects killed by suburban electric insect traps” by Timothy B. Frick and Douglas W. Tallamy, and “Neighbors help neighbors control urban mosquitoes” by Brian J. Johnson, David Brosch, Arlene Christiansen, Ed Wells, Martha Wells, Andre F. Bhandoola, Amy Milne, Sharon Garrison & Dina M. Fonseca, were consulted in preparing this episode.  

To learn more about the mosquitoes and how to defeat them, please view this video:

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Tigers, perhaps the most iconic and magnificent of all cats, remain in India, Nepal, Bhutan, Bangladesh, Myanmar, Russia, China, Thailand, Malaysia, Indonesia, Cambodia, Laos, and Vietnam according to the World Wildlife Fund. While the chance of spotting a tiger in the wild here in the DMV is nil, insect lovers and other naturalists can enjoy more than a dozen species of tiny six-legged tigers in forests, along the ocean and bay, and on riverbanks throughout our region. On a recent trip to the mighty Potomac River in Maryland, a budding seven-year-old naturalist discovered a gorgeous bronzed tiger beetle hunting prey in the sandy soil of a riverbank. We met the beautiful six-spotted green tiger beetle about this time last year along a bike trail not far away.

Tiger beetles are fierce predators as both juveniles (larvae) and as adults. Sabre-like mandibles impale soft-bodied insects and other invertebrates which make the riverbank their home. Most species of tiger beetle larvae spend their youth as sedentary hide-and-wait predators in galleries constructed in soil. When unsuspecting prey pass nearby, larvae pop out of their lair and spear their hapless victim. Larvae enlarge galleries as they grow and develop.

Bronzed tiger beetles dash about a sandy riverbank along the Potomac on a sunny afternoon. A curious tiger stares back at an iPhone before moving in for a closer look. Watch at full speed and then at 70% reduced speed as a bronzed tiger jets away from an annoying stick.

Life along a riverbank is fraught with peril as rivers like the Potomac often flood and submerge adjacent land. For mobile adult beetles, as waters rise, flight or a mad dash can take them out of harm’s way. But what fate awaits soil dwelling beetle larvae when waters rise? Galleries submerged by floodwaters soon become severely oxygen poor and these tiny creatures need oxygen for survival. Scientists have discovered that some species of tiger beetles inhabiting water-logged soils switch their metabolic activity from oxygen-driven to anaerobic metabolism (oxygen not-needed) during times of immersion. In studies, different species of tiger beetles survived 60 to 120 hours of submersion. Yikes! Wish I could hold my breath that long. And when soils become a bit too soggy, guess what, larvae of at least one species of tiger beetle, the hairy tiger beetle, simply move out and find soils with lower moisture levels where they can survive and thrive. Unfortunately, as rivers are dammed and lakes form, riverbanks with just the right moisture levels may be harder to find for tiger beetles on the move. Scientists fear these river-dwelling species may fail in their attempts to relocate to less soggy soils. In several locations, subspecies of hairy tiger beetles have declined dramatically in recent years, likely due to human-made alterations of their habitat. In addition to dams that dramatically alter riparian ecosystems, soil compaction by human foot-traffic along river banks may contribute to the demise of tiger beetles along rivers and lakes. Tread lightly and carefully along riverbanks and try to stick to existing trails rather than blazing new ones, lest we further disrupt habitats of these tiny but magnificent tigers. 

Acknowledgements

Two excellent articles “Movement of Cicindela hirticollis Say Larvae in Response to Moisture and Flooding” by Mathew Louis Brust, William Wyatt Hoback, Kerri Farnsworth Skinner and Charles Barry Knisley, and “Hypoxia tolerance in adult and larval Cicindela tiger beetles varies by life history but not habitat association” by Mathew L. Brust and W. Wyatt Hoback were used to prepare this episode. Thanks to eagle-eyed Abby for spotting a pretty bronzed tiger beetle that provided the inspiration for this episode.

Bug of the Week thanks our regular viewers and sends a hearty welcome to the many enthusiastic new Ze Frank viewers who have subscribed. Please learn more facts about bugs at our blog. 

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Ok, so I thought this was a catchy title but really very few insects give live birth to their young. Aphids and some flies birth living young, however, the vast majority of insects deposit eggs which then hatch, releasing their spawn into the world. Circling back to the topic, last week we received numerous reports of spotted lanternfly eggs hatching in the DMV and in other states nearby. As we learned in a previous episode, invasive Tree of Heaven plays a key role as a food source for spotted lanternfly. Due to its widespread distribution and abundance in Washington County, MD some joke that Tree of Heaven is the titular state tree of Maryland.  To witness the hatching phenomenon of spotted lanternfly, we traveled to a small woodlot near Hagerstown, Maryland. Here scores of Tree of Heaven and several other species were heavily infested with spotted lanternfly. In brilliant morning sunlight we watched dozens of spotted lanternfly nymphs escape the confines of their eggs and transform from ghostly, newly hatched nymphs into bespectacled, black tick-like creatures. Within an hour, highly mobile nymphs made a mad dash upward to the canopy of the tree. On a cherry tree nearby, small herds of black and white polka-dotted nymphs had settled in to suck sap from leaves.  

Watch as spotted lanternfly nymphs hatch from eggs deposited on Tree of Heaven by their mother last autumn. These time-lapse video segments reveal wraithlike nymphs rising from their egg cases over the span of about a half an hour. After hatching, nymphs move away from the mass. Within an hour, their body color changes from creamy white to jet black with pure white spots. They scramble to the tree’s canopy to suck sap from leaves. Nearby, a small herd of slightly older nymphs assemble to feed on vascular elements within a cherry leaf.

At this time in the growing season, what can you do if you discover spotted lanternfly nymphs on plants in your landscape or garden? Nymphs are often found feeding on the underside of leaves. By holding a good old red solo cup filled with soapy water (no, not beer) beneath the leaf and tapping the leaf from above, nymphs will take a suicidal leap into the water. It turns out they are not good swimmers. If you don’t mind a more intimate approach to eliminating nymphs, they are easily crushed between fingers if you can catch them. They are really good at hopping away from predators and avenging humans. Another approach, of course, is to use insecticidal sprays. My favorites are those labeled for use in organic food production. These will be gentle on non-target organisms and help conserve them in our gardens and landscapes. Products may include natural pyrethrins, which provide excellent control of nymphs, or insecticidal soaps and oils, including neem oil, that provide good control. Once nymphs have moved from easily accessible low-lying vegetation to upper tree canopies, systemic insecticides may be used to reduce resident populations. We are fortunate to have well-trained arborists and landscapers who can apply highly effective insecticides to control lanternflies on trees and shrubs.  Many web-based information sources recommend scraping eggs masses from trees before they hatch. However, a recent publication by scientists at Penn State indicates that less than 2% of lanternfly egg masses are found in a reachable distance from the ground. They suggest a variety of tactics should be used when dealing with spotted lanternflies.

On the brighter side of this somewhat disturbing invasion is the fact that many of our indigenous beneficial organisms including spiders, praying mantises, and assassin bugs have demonstrated a fondness for snacking on lanternflies. In addition, naturally occurring indigenous fungi infect and kill lanternfly nymphs and adults. Some of these fungi have been formulated to be sprayed on lanternflies and are available commercially. In many locations, Mother Nature’s agents of doom inflict what is known as biotic resistance to these unwelcome invaders, dramatically reducing lanternfly populations. Regional quarantines in several jurisdictions help slow the spread of this clever hitch hiker. As we learn more about managing noisome lanternflies, we can be optimistic that our efforts in partnership with nature’s wisdom will reduce threats imposed by these invaders.    

Acknowledgements

Bug of the Week thanks Josh for finding the location to film spotted lanternflies and a gracious landowner who shared her trees and insects. Paula Shrewsbury provided images and helped wrangle jumpy insects. To learn more about spotted lanternflies, please visit Penn State’s fantastic fact-filled spotted lanternfly website: https://extension.psu.edu/spotted-lanternfly-management-guide Learn more about spotted lanternflies at recent stories on NBCs Today Show and WBALs Sunday Morning Show:

https://www.today.com/video/officials-warn-spotted-lanternflies-are-set-to-return-this-spring-171253317582

https://www.wbaltv.com/article/tips-on-dealing-spotted-lantern-fly-the-bug-guy/43687299

To learn more about regional quarantines in the DMV, please visit these websites:   

https://mda.maryland.gov/plants-pests/Pages/spotted-lantern-fly.aspx

https://www.vdacs.virginia.gov/plant-industry-services-spotted-lanternfly.shtml

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One of the joys of spring is observing the antics of insects and their relatives as they resume their activities outdoors. To celebrate this annual renaissance, the Department of Entomology hosts an award-winning Insect Petting Zoo as part of the Maryland Day Gala at the College Park Campus of the University of Maryland on Saturday, April 29, from 10 am to 3 pm. The Insect Petting Zoo is in the Plant Sciences Building on the ground floor directly across from the Regents Drive parking garage.

This year’s petting zoo will feature an incomparable ensemble of friendly, ferocious, and creepy crawly creatures. A visit to the petting zoo is sure to delight insect aficionados of all ages. This year’s extravaganza features bugs from around your home and around the world. Giant Lubber locusts straight from the Everglades of Florida will reveal their favorite delicacies and how they defend themselves from being eaten. Vietnamese and Australian walking sticks are true masters of disguise and giant Madagascar hissing cockroaches will blow your mind with their size and agility. Watch out for the Whip Scorpion that has a clever trick up its sleeve, or should we say its tail, to thwart attacks by enemies. If you are lucky, you might catch a glimpse of a Black widow spider with a bright red hourglass tattooed on her abdomen, a ferocious Green Tiger beetle hungry for fresh meat, or a Carpenter bee buzzing about its cage. The arts of trickery, mimicry, thanatosis, and other feats of deception and disguise will be revealed by Blue Death Feigning beetles, the European sowbug (roly poly),  Darkling beetles (armored stink beetle), and the remarkable, petite African ghost mantis.

Come to the Insect Petting Zoo at Maryland Day, Saturday April 29 at the University of Maryland, College Park. Travel around the world to meet rocking Vietnamese walking sticks and giant Australian walking sticks pretending to be dead leaves. Amazing Malaysian leaf insects will try to fool you and watch out for the whip scorpion and its smelly surprise. Hold a giant tarantula if you dare and look at, but don’t touch, the black widow spider. Meet the deadliest creature on our planet, blood-thirsty mosquitoes, and pet a friendly, furry Eastern tent caterpillar. Fast moving green tiger beetles will prowl their cage while blue death feigning beetles will be stuck in second gear. Learn why carpenter bees make holes in your deck and why iconic honey bees and their kin are imperiled in our rapidly changing world.

The Insect Zoo is not just a treat for the eyes. Children of all ages will have the chance to hold and touch (with parental permission of course) a multi-legged millipede from the desert or a hairy Eastern tent caterpillar from a cherry tree. The very brave may even have a chance to hold a giant tarantula. If touching isn’t your thing, then you can listen to the buzzing of a bee or the hissing of a cockroach from Madagascar. Meet face to face the number one killer of humans on the planet – dreaded bloodthirsty mosquitoes. Curious smells are on the menu as well. Learn what unwelcome house guest has the aroma of cilantro and discover an arachnid with the pungent odor of vinegar. If you are feeling social, investigate the wonders of perhaps our most important social insect, the honey bee. Stop by the invasive species corner and meet dastardly Emerald Ash Borers, the nefarious home invader Brown Marmorated Stink Bug, and the newcomer in our region, Spotted Lanternfly.

Children can collect insect stickers and the first 600 visitors may take home a Terrapin Lady Beetle to release in their garden to put a beat-down on insect pests lurking there. 

Don’t miss The Swamp – If you enjoy the life aquatic, be sure to stop by The Swamp across the hall and learn how dragonflies capture their prey and how diving beetles extract oxygen from water.

So, come one, come all to explore Maryland Day and the Insect Petting Zoo!

To learn more about Maryland Day and the location of the Insect Petting Zoo, please click on the following links:

Maryland Day:  https://marylandday.umd.edu/

Insect Petting Zoo and Discover a Swamp, 10am-3pm: https://marylandday.umd.edu/events?neighborhood=ag-day

Acknowledgements

Bug of the Week thanks Dr. Paula Shrewsbury for organizing the Insect Petting Zoo and Dr. Bill Lamp for organizing The Swamp at Maryland Day. Special thanks to Todd Waters and Chris Sargent for making our arthropods the happiest six and eight- legged creatures on the planet.

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About this time each spring, wooden structures in the DMV provide opportunity to witness an unparalleled display of aerial antics conducted by male carpenter bees. Frequently, humans who venture too near children’s wooden play sets, benches, railings, mailbox posts, decks, and houses with cedar siding are divebombed by territorial male carpenter bees that jealously guard key nesting sites for their mates. Carpenter bees resemble bumble bees in size and appearance, but notably have a glossy black abdomen rather than the hairy body sported by the bumble bee. Female carpenter bees build galleries in wood to serve as nurseries for their young. Male carpenter bees go to great lengths to convince potential mates of their worthiness by selecting and defending nesting sites. When other male carpenter bees approach defended territories, remarkable aerial battles ensue. Swooping, grappling, and biting often result in both combatants tumbling to earth before one withdraws from the fray. I watched one victorious male guard a nesting site and soon a lovely and somewhat coquettish lady carpenter bee arrived. She rested on the wooden bench guarded by her suitor, and a short but energetic romantic interlude ensued. As far as I could tell, the male flew off somewhere, perhaps for more battles or romantic conquests, but the female bee had different matters to attend.

After mating, the she bee begins the task of excavating a hole in the wooden structure to be used as a nursery for her brood. Her powerful mandibles create a slightly oval to almost perfectly round hole as she penetrates the wood to the depth of about a half inch. She then makes a right angle turn and continues tunneling parallel to the grain of the wood, excavating a series of brood-cells in a linear tunnel. In a piece of wood removed from one of the benches, I observed several tunnels more than a foot in length, some of which branched into secondary galleries. Each tunnel contained as many as thirteen individual brood-cells. To construct each tunnel represents more than a month’s worth of chewing and one has to admire the determination of these industrious gals in excavating a home for their young. After the chambers are built, they are meticulously cleaned and filled with bee bread, a nutritious mixture of pollen, nectar, and secretions from glands on the female’s body. Bee bread serves as the food for the young carpenter bees. Starting at the end farthest from the entrance, the female deposits an egg in each brood-cell. Each egg hatches into a legless larva that eats bee bread and develops during the course of spring and summer. In brood-cells furthest from the entrance, older larvae complete development first and after emerging from the pupa in late summer, these new adults push their way past brothers and sisters to escape the gallery and search for nectar and pollen. As summer wanes and autumn waxes, after foraging all day bees return to their galleries to spend the night. With the end of plants blossoming in the fall, carpenter bees return to their snug tunnels to chill out, protected from the ravages of winter.

Wooden structures like this play set bear telltale damage as woodpeckers search for carpenter bees inside the wood. Male carpenter bees zoom around nearby, sensing that nubile female bees will soon emerge from these galleries. They divebomb other competing males and nosy humans, aggressively defending their mating territory. When females emerge, they will quickly be mated by diligent guy bees patrolling nearby. Once inseminated, females build new galleries in wooden structures creating nesting sites for their young.

Watching humans duck and cover as male carpenters challenged intruders who dared to enter their territory is almost as entertaining as watching aerial battles among male bees. However, male carpenter bees lack stingers and are therefore unable to sting. Although the gals are equipped to sting, I have never been stung myself nor have I heard of anyone who was harmed by these fascinating creatures. Carpenter bees do cause some damage to wooden structures; however, these entertaining native insects provide important services in pollinating our trees, shrubs, and crops. At past events such as Maryland Day at the University of Maryland at College Park (to be held this year on April 29), over a thousand people visit our Insect Petting Zoo, and our resident carpenter bees received much interest and attention. Several children and a few courageous adults held the male bees and were fascinating by buzzing sounds and vibrations generated by flight muscles that power the wings. In discussing the antics and activities of carpenter bees, I was heartened to learn that most folks take a “live and let live” approach to dealing with the carpenters. As one lady put it, “This is their world too, you know.” I know, well said.

Acknowledgements

Special thanks to John Davidson for sharing good carpenter bee stories with me. “Bionomics of large carpenter bees of the genus Xylocopa” by Gerling, Velthuis, and Hefetz” was used as a reference for this Bug of the Week.

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Last week we visited a feral colony of honey bees energetically engaged in their business of pollination in downtown Greenville, South Carolina. This week we jump some 500 miles north to the banks of the mighty Potomac River near Antietam National Battlefield. Along the alluvial banks of the river, galleries of ground nesting bees abound. And on an 80-degree day last week, fleets of busy pollinators darted among dandelions and hovered near patches of Dutchman’s breeches and Virginia bluebells. One particularly frenetic insect appeared to be some kind of furry bee with a wickedly long tongue that probed the depths of florets. Closer inspection revealed the fancy flier’s flight gear included one pair of wings not two, a sure sign that this was a fly and not a true bee. The close resemblance of these hairy flies to pollinators such as honey bees and bumble bees has earned them the name bee fly. Bee flies have a remarkably long mouthpart called a proboscis that is modified to reach deep into flowers to sip the carbohydrate rich nectar, which is an important source of energy for these hyperactive fliers. Although they do not deliberately collect pollen as a source of food for themselves or their young as do bees, their hairy coat traps pollen and provides convenient transport of pollen from one plant to another.

On a chilly spring morning a bee fly performs a pre-flight warm-up by rapidly fluttering its wings. Bee flies require huge amounts of carbohydrates, which they obtain from nectar, to power flight. Watch as the Greater Bee Fly, Bombylius major, gathers nectar from a dandelion with its ridiculously long proboscis. Busy mouthparts dance across the blossom. Bee fly cousins with tongues as long as their bodies provide similar pollination services to beautiful wildflowers in the Mojave Desert.

The fact that bee flies are common around flowers during this season of high bee activity is more than just a coincidence. Bee flies have a seamier side that often proves deadly for other species of insects. When solitary ground nesting bees such as halictids, colletids, and andrenids visit a flower and get a full load of nectar and pollen, they head back to their nest to provision it with food for their young. The wily and agile bee fly follows a bee back to its nest and deposits an egg in or near the burrow of the bee. After hatching, the fly larva enters the gallery of the bee. Some species of bee flies first consume provisions left behind by the solitary bee before turning their attention to the developing baby bees. They attach to the skin of the larval bee and suck its blood, which is the source of nutrients for the developing larva of the bee fly. A fascinating account by the great naturalist Jean-Henri Fabre (1823 – 1915) describes the attack of a bee fly larva in the genus Anthrax (described below as the worm and nursling) on a leafcutter bee larva in the genus Chalicodoma (called the nurse). “The worm is fixed by its sucker to any convenient part of the nurse, plump and fat as butter. It is ready to break off its kiss suddenly, should anything disquiet it, and to resume it as easily when tranquility is restored. No Lamb enjoys greater liberty with its mother’s teat. After three or four days of this contact of the nurse and nursling, the former, at first replete and endowed with the glossy skin that is a sign of health, begins to assume a withered aspect. Her sides fall in, her fresh color fades, her skin becomes covered with little folds and gives evidence of an appreciable shrinking in this breast which, instead of milk, yields fat and blood. A week is hardly past before the progress of the exhaustion becomes startlingly rapid. The nurse is flabby and wrinkled, as though borne down by her own weight, like a very slack object. If I move her from her place, she flops and sprawls like a half-filled water bottle over the new supporting plane. But the Anthrax’ kiss goes on emptying her: soon she is but a sort of shriveled lard bag, decreasing from hour to hour, from which the sucker draws a few last oily drains. At length, between the twelfth and the fifteenth day, all that remains of the larva of the mason bee is a white granule, hardly as large as a pin’s head.” Yikes!

Bee flies are a large diverse group known to attack and kill caterpillars, eggs of grasshoppers, and larvae of beetles, as well as baby bees. So, bees and other insects beware, bee flies are on the wing.

Acknowledgements

The Master Naturalist Program of the University of Maryland and eagle-eyed Dr. Shrewsbury provided the inspiration for this episode, a version of which was published pre-pandemic in 2018. The wonderful references “Insects: Their natural history and diversity” by Stephen Marshall, “The Life of the Fly” by J. Henri Fabre and the Maryland Biodiversity Project were used as references for this episode.

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To escape late winter doldrums, recent episodes of Bug of the Week visited Florida’s Everglades to meet creepy smiley face spiders and the largest grasshopper in the US. This week we make a stop in beautiful downtown Greenville, South Carolina, and the Swamp Rabbit Trail. After dining on fresh pastries and fueling up on strong java, it’s time to enjoy an increasingly rare occurrence, honey bees nesting in the cavity of a tree. As Winnie the Pooh knows, honey bees evolved to build hives in natural cavities like tree hollows rather than rectangular boxes built by humans. As a kid growing up in once rural Randolph, New Jersey, it was not unusual to know the location of a few honey bee trees in the forests. However, following the accidental introduction of parasitic Varroa mites into the US in the late 1980’s, both managed and feral honeybees have struggled for survival.

Enjoy one of Mother Nature’s most important pollinators busy at work along the Swamp Rabbit Trail in downtown Greenville, South Carolina. Honey bees made a traditional home in the hollow of an ancient Osage orange tree. Watch as workers return to the hive, leg baskets overflowing with bright yellow pollen, while outbound workers quickly depart to gather new loads of pollen and nectar for their nestmates. Nearby a fragrant white hyacinth seems just the right place to load up on supplies. No humans or honey bees were disturbed or harmed in the making of this video.

Back in 2015, Bug of the Week reviewed several challenges facing our imperiled honey bees. The appearance of a deadly phenomenon called Colony Collapse Disorder, or CCD, grabbed national attention in 2006 when many commercial beekeepers reported unusually large losses of honeybee colonies in several locations in the United States. When CCD strikes a hive, worker bees simply disappear leaving behind the queen, a few young attendant workers, and cells full of pollen and brood. One of the defining characteristics of CCD is the absence of dead bees in the colony. Without a full contingent of hardy workers, the queen and brood are doomed and the colony collapses. Soon after CCD was discovered, national surveys of beekeepers were conducted to determine the magnitude of the problem. Between September 2006 and March 2007, beekeepers lost approximately 32% of their hives. During a similar period in 2007 and 2008, beekeepers in general lost about 36% of their colonies. One important trend in the colony loss phenomenon has been a reduction in losses attributed to CCD. But hives continue to falter and fail.

What are some of the factors connected with the demise of honey bee colonies in the US? The causes of CCD and hive loss are not fully understood, but researchers have made great progress identifying some of the culprits in this mystery. A recent article by researcher Selina Buckner and colleagues identified a multitude of factors harmful to the health and vitality of honey bee colonies. Factors include those connected to living organisms (biotic factors) and those associated with the non-living environment (abiotic factors). Premier among the biotic factors are invasive parasitic mites and viruses they carry, unhealthy queen honey bees, and variable, scarce, and sometimes unreliable sources of nectar and pollen for bees. On the abiotic side, extreme weather events threaten honey bees and plants on which they depend. Human-made environmental inputs of fungicides and insecticides conspire with these other forces to extinguish hives of honey bees. In a recent summary of surveys connected to honey bee colony loss, scientists discovered that small scale, backyard beekeepers experienced higher rates of winter colony loss, which ranged from 36% to 51% in winters between 2017 and 2020, compared to commercial beekeepers where winter losses ranged from ~ 26% to ~ 32% during the same time frame. By contrast, summer colony losses were generally higher for commercial beekeepers, ranging from ~21% to ~ 28% compared to backyard beekeepers where losses ranged from ~15% to ~22% over three growing seasons. In addition to differences in the size and mode of operation, backyard vs commercial, shifting regional and seasonal patterns of colony loss provide a complex tableau where mites and their associated viruses, queen issues, starvation, and pesticides, along with several other factors, imperil these iconic pollinators here in the US. But circling back to Greenville, SC, where this tale began, what a treasure to behold an Osage orange tree full of busy honey bees along an urban park trail where curious passersby can enjoy one of Mother Nature’s most iconic pollinators at work.

Acknowledgements      

Bug of the Week thanks Nathalie Steinhauer and the Bee Informed Partnership for providing information used in this episode. The amazing article “A national survey of managed honey bee colony losses in the USA” by Selina Bruckner, Mikayla Wilson, Dan Aurell, Karen Rennich, Dennis, vanEngelsdorp, Nathalie Steinhauer and Geoffrey R. Williams was used as a resource for this article. Special thanks to Dr. Paula Shrewsbury for images and discovering the bee tree that inspired this episode.

To learn a ton about honey bees, their successes and travails, visit the Bee Informed website on a regular basis: http://beeinformed.org/

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Last week we escaped the chilly mid-Atlantic to visit the smiley-faced spiny orbweaver in the Everglades of Florida. This week we return to warmth of southern Florida to learn about the largest grasshopper in North America, the eastern lubber grasshopper. With spring off to a fast start in much of the eastern United States, it’s not surprising that eggs deposited in the soil by female lubbers last year have already begun to hatch. What is surprising is the affinity these tiny newborn grasshoppers have for the side of my tent as they warmed themselves in the morning sunlight after a chilly night in the Everglades. Hard to beat an early morning visit from a dozen or so pretty grasshoppers. Nearby, slightly older lubbers were busy defoliating leaves of hairy beggar ticks. Their gregarious behavior and striking coloration of brilliant yellow, orange, or red lines and patches on a jet-black background make them hard to miss.

Tiny lubber grasshoppers warm themselves on the sunny side of my tent while slightly older nymphs dine on leaves of beggar tick nearby. As nymphs age and molt, color patterns may change and wing buds appear just behind the head. As adults, whether it’s a romantic interlude in the sunshine or a stroll along the boardwalk to gawk at humans, heavily armored and chemically defended eastern lubber grasshoppers seem to fear no one.

One would think that these brightly colored creatures that will grow to be one of the largest insects in the United States would evade humans and be wary of enemies, or perhaps employ camouflage to avoid the beaks and jaws of hungry predators. But, oh no, these critters boldly walk, dine, and mate in full sight. How do they do it? What special powers do lubber grasshoppers possess to move about a dangerous landscape with impunity? Let’s revisit some of the remarkable defenses of lubber grasshoppers we described in a previous episode. First, we’ll take a look at some defensive morphologies and behaviors of lubbers. The body of lubbers is protected by sturdy plates of chitin, body armor that can withstand attacks of many smaller predators. As they molt and grow larger, lubber legs are festooned with rows of strong spines capable of piercing human and, presumably, reptilian flesh (but don’t try this for yourself). In addition to spiny legs, the powerful jaws of the lubber could deliver a nasty bite to predators.

The Latin epithet, microptera, found in the species name of this critter literally means “small wing.” Indeed, wings of the lubber are so small they are no longer functional for flight. This locust moves through the world on legs rather than wings. However, the hind wing of the lubber nonetheless serves a very important function. Its brilliant scarlet color serves as a warning to visually astute predators. Those with lubber experience learn that messing with lubbers will result in punishing chemical warfare. The first line of chemical defense, one regularly employed by many insects, is vomit. Across the insect realm from caterpillars to grasshoppers, regurgitation of disgusting gut contents is often employed as a defense when predators attack. As kids we learned that grasshoppers would ‘puke tobacco juice’ (technical terms) onto our fingers and hands when we grabbed them. In addition to staining skin, tobacco juice was kind of stinky. Clever studies revealed that lubbers often dine on plants whose leaves are loaded with bitter secondary plant chemicals. That may be why the vomit of lubbers is repellent to invertebrate predators such as ants.

If this array of defensives tactics is not enough, lubbers have one more trick – repellent froth. When under attack, eastern lubber locusts produce noxious, frothy, foam from a breathing port called a spiracle on the side of their body. This foam is a veritable witch’s brew of aromatic and irritating chemicals that hiss and bubble upon release. Body armor, spines, and chemical weapons help these ancient giants of the grasshopper kingdom survive and thrive in an ever-changing world.     

Acknowledgements

Delightful references including “Large size as an antipredator defense in an insect” by Douglas Whitman and Shawn Vincent, “Secret weapons” by Thomas Eisner, Maria Eisner, and Melody Siegler, and “For the love of insects” by Thomas Eisner formed the factual basis for this week’s episode. Thanks to Dr. Shrewsbury for wrangling and photographing lubber locusts and to the remarkable Big Cypress Nature Preserve and Audubon Corkscrew Swamp Sanctuary for providing inspiration and thespians for this week’s episode.

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After two months of record warmth in the DMV, Mother Nature decided that a late winter chill-down is in order for the greater Washington-metropolitan area. With blossoms of cherries and magnolias in peril and insect activity still in a state of languor, it’s time for a road trip to warmer parts of our nation. First stop, Big Cypress National Preserve in the beautiful, buggy Everglades. While walking along a gator-infested bayou and trying not to disturb any large, sunbathing reptilians, our adventurous party of four almost collided with a magnificent orb web constructed across a swampy trail. At the center of the orb a ghostly face with two black eyes, a broad toothy grin, and a halo of scarlet spines smiled at us. This small but scary spider was the ghoulishly gorgeous spiny orbweaver. Locally known as the Florida crab spider, this species ranges from Florida to Argentina in North, Central, and South America. As is the case with many spiders, at 10 – 13 mm in width, females are much larger than their puny mates, which may be only 2 – 3 mm wide.

Webs of the spiny orbweaver are a masterpiece of functional beauty. Strong non-sticky radial lines support concentric circles of sticky prey-snaring strands. At the center of the web, females rest in an open area of non-sticky lines awaiting arrival of prey. When a fly, beetle, or small moth is snared by a viscous strand of silk, the female plucks radial strands with her forelegs to vibrate attendant sticky strands, which further ensnare her hapless victim. Small prey may be carried by to the center of the web where they are consumed, while larger prey are bitten and paralyzed, then wrapped in silk to await a visit from the fangs of the hungry spider. Yikes!

This ten-foot gator isn’t the only one smiling in the Everglades on a beautiful sunny day. Nearby, a spiny orbweaver has constructed its web. Adorned with scarlet spines and a ghoulish grin, a female boldly awaits a hapless victim to be ensnared by her web. White tufts of silk produced by the spider hang from several radial strands. These tufts may alert birds to the presence of the web and reduce destructive collisions that result in lost time and materials if a bird wrecks the web. These successful predators make their webs not only in the wild but in urban habitats near high rise condos as well.  Gator image by Paula Shrewsbury, PhD.

As you watch the video of the spider in its web, notice the white tufts of silk that adorn several of the radial lines of the web. What purpose do they serve? Well, many of us have experienced the disturbing thud of a bird hitting a large glass window. One way to reduce these unfortunate and sometimes lethal crashes is to paint patterns or attach stencils of birds on the window to alert our avian friends of an impending collision. Scientists believe that the white tufts on the orb weaver’s web may serve the same purpose. Highly visible gossamer tufts make the web more conspicuous and warn birds to steer clear of the delicate strands. While the web poses little peril to a bird, destruction of the web means precious time and material must be spent by the spider to reconstruct its food-snaring trap. With their malevolent smiles and thorny spines to confound predators and web adornments to ward off birds, spiny orbweavers thrive in the great river of grass known as the Everglades.

Acknowledgements

Bug of the Week thanks Jim, Anne, and Paula for spotting the spiny orbweaver and providing inspiration and images for this episode. Two great references “Spiny orb weaver spider, Gasteracantha cancriformis (Linnaeus)” by G. B. Edwards and “Biological and behavioral notes on Gasteracantha cancriformis (Arachnida: Araneidae)” by M. H. Muma were used to prepare this episode.

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In previous years we visited eastern tent caterpillars when they appeared on native black cherry trees in the last week of March or first week of April. Guess what; following the warmest January and February in the last 150 years in Washington, DC, these impatient tent makers began to hatch last week just up the road from DC in nearby College Park, Maryland. Under “normal” climatic conditions, this would pose no real concern for caterpillars, but this year trouble may be brewing. While the hatch of caterpillars is underway, some black cherry trees which normally provide leaves to sustain eastern tent caterpillars, have yet to heed Mother Nature’s wake-up call. Fascinating studies of eastern tent caterpillars in Washington, DC, demonstrated that warm winter temperatures induced earlier hatching of caterpillars, which resulted in reduced survival of caterpillars due to starvation – suicidal emergence.

Watch as an eastern tent caterpillar emerges from its egg. It will join dozens of siblings that have already hatched on the surface of an egg mass deposited by its mother last year on a black cherry tree. But will this early arrival spell doom by starvation for the caterpillars on a tree yet to produce tender buds and leaves to sustain caterpillar growth? Scientists fear that climate change may result in harmful seasonal mismatches between herbivores, pollinators, and plants on which they depend.

Scientists found that early starvation put a serious beat-down on survival of hatchlings. These studies also demonstrated that eastern tent caterpillars from different regions vary in their ability to survive periods of starvation. Populations of resilient eastern tent caterpillars from Georgia were able to survive starvation for periods that were 30 % longer than tent caterpillars from DC. As climate change continues to create havoc for long-evolved relationships between plants and insects, and with chilly rains and freezing nights forecast over the next two weeks, will wild cherries wait for warmer temperatures to break bud and expand their leaves? And if foliation is delayed, what will it mean for our cherry-loving tent caterpillars? Only time will tell.

Acknowledgements

The enlightening article, “Warming affects hatching time and early season survival of eastern tent caterpillars” by Mariana Abarca and John T. Lill provided inspiration and insights for this episode. To learn a bit more about eastern tent caterpillars, how to remove them and how to enjoy them, please visit this episode of Bug of the Week – Food for caterpillars, food for birds: Cherry trees and Eastern tent caterpillars, Malacosoma americanum.

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