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Several years ago while at work pulling weeds in a bed of chrysanthemums, I noticed a liberal sprinkling of caterpillar frass decorating blossoms of several plants. Frass, the euphemistic term for the pellet-like, powdery, or sawdust-like excrement of herbivorous insects, often provides a clue alerting one to the presence of an insect on or in a plant. A thorough inspection of my mums failed to disclose the culprit, but as I watched the plant later while enjoying a leisurely cup of coffee, I noticed a small cluster of flowery debris swaying on a blossom. A closer inspection revealed a cleverly disguised caterpillar cloaked in purple petals busily dining on the flower head. Recently, several eagle-eyed naturalists have reported similar sightings on mints and Joe Pye weeds in gardens and meadows. While I have yet to discover them in my garden this season, if the rain ever abates, I will renew my search with vigor.

This little trickster is the camouflaged looper, Synchlora aerate. Bedecked with bits of foliage and flower petals, it is sometimes detected when performing a herky-jerky waltz as it moves from one meal to the next. We’ve all seen the movie where a warrior incorporates leaves and branches into a camouflaged uniform to hide from the enemy, right? Next time you see this in a flick, just remember that a caterpillar thought of it first several million years ago. If you have a moment to sit and watch a stellar performance you may see the looper sway back and forth, adding to the illusion of a plant part being blown by the wind.

Imagine you are a camouflaged looper. When dining on coreopsis, browns and yellows seem the smart camo choice. But when crimson mums are on the menu, better go with the crimson petals. And when you depart for the next meal add a little “I’m just a petal swaying in the breeze” movement to your routine to fool the eyes of hungry predators.

Loopers are members of a large family of moths known as geometrids. The name geometrid stems from Greek roots meaning “earth measure”. Another common name for some geometrid caterpillars is inchworms. As they cruise about the blossoms, loopers and inchworms do appear to measure the earth inch by inch. In addition to my chrysanthemums, camouflaged loopers eat many other types of flowers including ageratum, aster, black-eyed Susan, boneset, coreopsis, daisy, goldenrod, Joe Pye weed, ragweed, raspberry, rose, sage, St. John’s wort, and yarrow. The adult stage of the camouflaged looper is known as the wavy-lined emerald and it is every bit as beautiful as the larva. So next time you see some unexpected frass on your flower blossoms, take a few moments to observe your flowers with an eye out for these masters of disguise.

Can you spot the camouflaged looper on this mint? Well, for the one eating goldenrod some labels and an arrow might help. Photo credits: mint – Mara McCall, goldenrod – Mike Raupp.

Acknowledgements

Many thanks to our observant naturalists who discovered camouflaged loopers in their landscape, especially Mara McCall and Glen Schulze for providing the inspiration for this episode and for providing cool images of these rascals. The wonderful reference “Caterpillars of Eastern North America” by David Wagner was used as a reference for this Bug of the Week.

BTW, in the feature image the head is on the left and the rear end is on the right.

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Although this year has been tough on some charismatic butterflies, it seems to have been a great year for wasps. Earlier this year giant murder hornets made a sensational splash when they were discovered in the Pacific Northwest. And here in the DMV we have visited cow killers hunting bumble bees, great black wasps capturing katydids, cicada killers living up to their name, and tiny Aphidius wasps exiting the rear end of aphids. This week, let’s visit a pair of gorgeous and really cool wasps intent on annihilating   dastardly beetle pests in our lawns and gardens.

The beetle pests these wasps focus on include larval stages (a.k.a. grubs) of green June beetles, Japanese beetles, Oriental beetles, Asiatic garden beetles, and other members of the scarab clan that dwell in soil and devour roots of our lawn grasses in addition to those of annual and perennial plants. As adults these beetles, known as scarabs, strip leaves and blossoms of hundreds of species of ornamental plants and wholesome vegetables. Abundant spring and summer rains conducive to grub survival have turned my flower beds into ideal breeding sites for these rascals. But in Mother Nature’s system of checks and balances, it is not unusual to see populations of predators and parasites rise shortly after populations of their prey increase. Over the past week or so, several folks have commented on hordes of dark winged wasps cruising back and forth a foot or so over their turf. Most of these sightings are digger wasps, members of a family known as Scoliidae. The digger wasp moniker stems from the impressive ability of these fierce fliers to locate white grubs beneath the surface of the earth, tunnel through the dirt, deliver a paralyzing sting, and deposit an egg on the skin of the grub. The hapless white grub is incapable of removing the egg, which soon hatches and the parasitic larva of the digger wasp slowly consumes its living victim. Glad I’m not a white grub.  After completing its development during summer and autumn, the wasp larva spins a silken cocoon, pupates, and then passes the winter in the burrow created by the grub. Fresh, new wasps emerge as adults the following August.

Whether it’s small white grubs in the soil or zany green June beetle grubs that crawl on their back across the ground, these pests face an awesome grim reaper when Scolia wasps come to my garden. Video credit: Michael J. Raupp

Several species of digger wasps can be found in the DMV and two in the limelight this time of year are Scolia dubia and Scolia nobilitata. Commonly known as the blue-winged digger wasp, Scolia dubia sports striking iridescent blue-black wings. Its body is black excepting the end of its fuzzy abdomen, which is reddish brown. Scolia dubia is easily recognized by one pair of bright yellow spots on either side of its abdomen. Its cousin, Scolia nobilitata, has smoky brown wings with two pair of yellow or off-white spots on its abdomen. These colorful beauties need energy to search for grubs and tunnel underground to find their victims. They can often be seen carbo-loading in preparation for the hunt on nectar-rich members of the mint family (Lamiaceae) such as mountain mint and spotted horse mint, and members of the aster family (Asteraceae) such as goldenrod. Lawns and landscape beds rampant with white grubs often attract squadrons of digger wasps flying in tight figure-eight patterns just above the ground, presumably hunting for prey. While they might appear scary, please understand that these wasps are not aggressive towards humans and that they are highly beneficial by virtue of the beat-down they put on white grubs. You can befriend these beneficial wasps by providing nectar sources, mints and asters, in your landscape and thereby invite them to hang around and find some pestiferous white grubs to serve as food for their offspring. As part of Mother Nature’s system of checks and balances, plant some flowers, sit back and relax on a warm autumn day and let them do their work.

Mints and goldenrods bring digger wasps like Scolia dubia to your garden on sunny days in late summer and autumn. After tanking up on energy-rich nectar, they will search for white grubs in your lawn and gardens, dig into the soil, and deposit eggs on hapless grubs. Upon hatching, wasp larvae devour the grubs and thereby help to rid your landscape of these noxious pests. Video credit: Marie Rojas and Michael J. Raupp

Acknowledgements

Bug of the Week thanks Marie Rojas for the awesome video of blue-winged digger wasps nectaring on mountain mint and Dr. Shrewsbury for providing the inspiration for this episode. The wonderful books “Destructive Turfgrass Insects” by Dan Potter and “Bees, Wasps, and Ants” by Eric Grissell were used as references.

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During a recent conversation with a Master Naturalist over some holes in leaves of ornamental mallows, I shared my inability to find one of the usual suspects associated with shredded mallow leaves, the mallow sawfly, a wasp we met in a previous episode. My rather public response elicited a flurry of rejoinders from gardeners and naturalists whose dogwoods were ravaged this year by another member of the sawfly clan, called the dogwood sawfly. Sawflies are primitive members of the bee and wasp order of insects known as the Hymenoptera. Unlike their kin, who either feast on the flesh of other arthropods or dine on nectar and pollen of plants, several families of sawflies feed on leaves. So this week seems to be a good time to catch up with a couple of fascinating leaf-munching sawflies.

Let’s start with dogwood sawfly. One of the favored hosts of dogwood sawfly is grey dogwood, Cornus resemosa, but silky dogwood, Cornus amomum, and flowering dogwood, Cornus florida, are also on the menu. Winter is spent as a larva ensconced in a chamber built in rotting wood or sometimes structural wood, including siding. In spring larvae pupate and later, from May through July, adults will emerge to fly and find mates. Females deposit eggs on the undersurface of dogwood leaves in clutches numbering 100 or more. Eggs hatch and larvae consume leaf tissue and develop through summer. With the approach of autumn and imminent leaf drop, large sawfly larvae wander from dogwood trees to construct overwintering redoubts in wood. Although many sawfly larvae bear a striking resemblance to caterpillars, the larvae of moths and butterflies, most can be distinguished from Lepidoptera larvae by the number of pairs of appendages called prolegs found on abdominal body segments. In addition to three pairs of jointed walking legs on the thorax, most caterpillars have five or fewer pairs of fleshy prolegs on their abdominal segments. By contrast, in addition to the requisite three pairs of thoracic legs, most sawflies bear six or more pairs of prolegs.

Snaky dogwood sawfly larvae practice their curls beneath a leaf while an almost fully developed larva waves to the camera while searching for another meal.

As larvae, dogwood sawflies have, quite literally, a colorful juvenile history. After hatching from eggs, larvae are rather translucent yellowish creatures resembling gummy worms. As they develop and molt, specialized glands produce a snowy-white cloak of wax. Fully developed larvae shed the white waxy cloak and assume a dashing color scheme of yellow, white, and black. Why the chameleon routine? Well, some scientists have speculated that the brilliant white coloration and elongated body of young larvae may mimic a bird dropping and reduce the chance of predation. What self-respecting bird eats bird droppings, right? Another hypothesis suggests predators and small parasitic wasps may be unable or unwilling to effectively attack sawfly larvae through their cloak of wax.

Last week while on an adventure along the Patuxent River, I spied what I believed was a larva feeding on a patch of dastardly stilt grass. Delighted that something might be eating this aggressive invader, I investigated the critter and was disappointed to find nothing but an empty exoskeleton adorned with tufts of fluffy wax. Above the stilt grass towered a lovely black walnut tree whose leaves were disappearing down the gullets of another sawfly known as the butternut woollyworm.  Unlike its cousin the dogwood sawfly, this sawfly spends winter as a pupa in the soil enclosed in a durable case. In spring adults emerge and, after mating, females use their saw-like egg-laying appendage called an ovipositor to insert eggs into the mid-vein of walnut leaves. Newly hatched larvae are naked but soon develop a flocculent cloak of magnificent white wax. Upon molting from one instar to the next, this cloak is shed but often remains attached to a leaf for several days or falls on underlying vegetation like stilt grass to fool passing entomologists. In addition to black walnut, Juglans nigra, as their common name implies woollyworms also frequent butternut, Juglans cinerea, and have been reported from hickories, Carya spp. Over the next week or two, be on the lookout for these waxy sawflies on dogwoods and trees in the walnut family. Try to imagine what all the wax is about.  

High in the canopy, butternut woollyworms dine on leaves of a black walnut tree. Although their white waxy mane evokes visages of a shaggy dog or Cousin Itt, the flocculent cloak may dissuade attack by predators or parasitoids. White, waxy filaments dancing in the breeze may not advertise a tasty meal to vertebrate predators accustomed to naked caterpillars for dinner.

 Acknowledgements

This episode is dedicated to our friend Jimmy and in memory of Angela who shared their sawflies and inspired this Bug of the Week. The interesting articles “Be Alert for Dogwood Sawfly” by Joe Boggs, Insects that Feed on Trees and shrubs by Warren Johnson and Howard Lyon, and “Seasonal Cycle and Habits of the Butternut Woollyworm” by L.L. Hyche were consulted in preparation of this episode.

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In a previous episode of Bug of the Week, we lamented the scarcity of swallowtail butterflies in our gardens. Swallowtails have been scarce, but in my flower beds, bumble bees have been rocking. Bumble bees build nests in the ground, often in the former burrows of chipmunks, or sometimes in the hollow of a fallen tree. One might think a carefully constructed subterranean nest defended by bumble bees would be a pretty safe place to raise young. Most of the time this is true, but not so when red velvet ants are in town. This gorgeous insect is not an ant at all. Ants are social insects ruled by one or more queens governing a caste system of workers. Velvet ants are wasps in the family Mutillidae, a large group of solitary wasps that prey upon ground-nesting bees. We met a fast-moving velvet ant in the caldera of a sleeping Costa Rican volcano in a previous episode of Bug of the Week. The female velvet ant featured this week was discovered dashing about a local landscape. Red velvet ants are reported in most counties in Maryland and in addition to my home in Columbia, I have received images or specimens from Adamstown, Pasadena, Queenstown, and Bowie.  

Velvet ants, including the one we meet today, are part of a large mimicry ring. Bright contrasting colors of dozens of species of velvet ants, including Dasymutilla occidentalis, send a warning to potential predators that an attack will be met with a potent retaliatory response, a wicked sting. The easily recognized shared appearance of so many species of velvet ants is called Müllerian mimicry, first proposed by famed German naturalist Fritz Müller. Although lacking wings, the velvet ant is no slow poke. She runs like a demon while searching for a nest of unsuspecting bumble bees. Her powerful jaws and terrible stinger probably allow her to fight her way past bumble bee defenders and enter the brood chamber of the bee hive. In the brood chamber, bumble bee larvae are nourished and cared for by bee workers. The velvet ant lays a single egg on or near the bumble bee’s babes. This egg hatches into a velvet ant larva that consumes a developing bee. When fully developed, the wasp larva forms a pupa and later emerges as an adult velvet ant. Although female velvet ants are wingless, male velvet ants have wings that are shiny and jet black. The males fly about in search of flower nectar, pollen, and mates.  

It’s been a good year for bumble bees in my garden, working the blossoms and returning to nests, often abandoned chipmunk burrows. Elsewhere in the lawn, female red velvet ants prowl, searching for nests of ground nesting bees and wasps. If you see this amazing creature, avoid the urge to pick it up unless you yearn for a very memorable sting.

The lovely female velvet ant in this episode has yet another defense in addition to jaws and stinger. When grasped, she emitted a clearly audible squeaking sound. Squeaking, or stridulation in bug lingo, is a vibration produced by an insect. In this case stridulation occurs on the abdomen where one body part rubs against another. What purpose does the squeaking serve? Along with the bright red and black coloration, the loud squeak probably serves as a warning to any would-be predator that this beauty packs a punch. You see, the other common name for the red velvet ant is “cow killer.” When I grabbed one with a pair of forceps, an enormous, angry stinger emerged from the tip of her abdomen in search of something to punish. Some say that the sting of a velvet ant is strong enough to kill a cow. While this surely never happened, people stung by the velvet ant report a highly painful experience, long to be remembered.   

 Acknowledgements      

 We thank Tracy for the inspiration for this episode and for sharing an image of a beautiful eastern red velvet ant. Dr. Shrewsbury risked an awesome sting while capturing the subject for this episode. The fascinating article “North American velvet ants form one of the world’s largest known Müllerian mimicry complexes” by Joseph S. Wilson, Joshua P. Jahner, Matthew L. Forister, Erica S. Sheehan, Kevin A. Williams, and James P. Pitts, and the buzzy “Bees, wasps, and ants” by Eric Grissell were used to prepare this episode.

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Community gardens are fertile hunting grounds for interesting insects. On a recent visit to the West Side Community Garden in Columbia, Maryland, patches of milkweeds, mountain mints, and monardas were humming with pollinators large and small. In addition to the standard bees, butterflies, and flies, a couple of very impressive black wasps were busy in the florets. These were not social wasps like Asian giant hornets, European hornets, bald faced hornets, and yellow jackets, all colonial wasps that live in a nest ruled by a queen. These were solitary wasps, a part of the digger wasp clan. The larger of the two, Sphex pensylvanicus, goes by the name of great black wasp, while its smaller orange-legged cousin, Sphex nudus, is known as the katydid wasp.

As members of the digger clan, female great black wasps and katydid wasps excavate galleries a foot or more deep in the soil. This crypt will serve as the nursery and larder for the developing wasp larvae.  Female Sphex wasps search the treetops for those beautiful and melodious nighttime troubadours, the katydids we met last week. Once she locates her prey, she stings and transports her prize back to the subterranean burrow. Inside the burrow she provisions each brood cell with two to six victims and lays an egg on the underside of one katydid. Here is where this macabre tale gives me the willies. The katydids in the crypt are not really dead. They are just mostly dead, like the tortured Dread Pirate Roberts in the movie Princess Bride. Ah, but there will be no Miracle Max to rescue these unfortunate creatures. The venom of the great black wasp does not kill its prey; it merely paralyzes the victim. The moribund katydids are alive but cannot escape the jaws of the wasp larva as it proceeds to consume the hapless prey one by one over the span of about ten days. Whew, makes me glad I am not a katydid. Fully developed larvae spin cocoons in autumn and remain underground through winter, awaiting the return of summer before emerging from the earth to sip nectar and hunt katydids, crickets, and grasshoppers.

Sphex wasps are very fond of mountain mint and spotted horse mint. When the wasp probes the blossom for nectar, anthers dip down and release their pollen on its back.

One of the most curious pollination events takes place as great black wasps nectar at spotted beebalm, a.k.a horsemint (Monarda punctata), one of my favorite flowering plants by virtue of the vast number of insects it attracts. Unlike open-faced flowers such as sun flowers, horsemint provides a curious array of petals, anthers, and stigmas. Nectar fiends like the great black wasp land on petals and, as they probe deeper into the flower, pollen laden anthers dip down and discharge their yellow pollen grains onto the back of the wasp. As the insect moves from floret to floret pollen accumulates, turning the back of the great black wasp yellow. The transformation of the great black wasp to the great yellow-backed wasp never fails to amuse me. Spotted horse mint will always have a place in my garden.

Acknowledgements

The fascinating article, “The life-history and habits of the digger-wasp Ammobia pennsylvanica (Linn.)” by John A. Frisch was used as a reference for this episode. Bug of the Week thanks Dr. Shrewsbury for providing the inspiration and image for this story.

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Last week a friend inquired about all of the racket created by unseen insects as scorching days melted into somewhat less scorching nights here in the DMV. Near sunset as we enter the twilight zone, shrill daytime calls of several species of annual, a.k.a dog-day, cicadas are replaced by the courtship serenades of hopeful dusk-calling male cicadas and male katydids. Specific frequencies, amplitudes, and tonal patterns are used not only for species recognition, but also by females of each species to decide who will be the father of their nymphs. The winners of the entomological version of ‘The Voice’ win the right to mate and thereby move on to the finals evolutionarily, so to speak. Cicadas produce sound by vibrating a membranous, drumhead-like organ on the sides of their abdomen called a tymbal. The enlarged and mostly hollow abdomen of the cicada acts as an amplification chamber producing vibrations of 100 decibels, one of the loudest sounds in the animal world.

Watch as an annual cicada scales a tree before taking flight to the canopy. The abdomen of a daytime-singing cicada vibrates as he woos his mate. Leaf-mimicking angle-wing katydids are common in our area. Grooming appears to be an important part of the daily routine. To hear the gentle call of the greater angle-wing katydid, please click on this link. http://songsofinsects.com/katydids/greater-anglewing

Katydids use a very different anatomical mechanism to create sound. The katydid’s remarkable musical anatomy includes a forewing with a series of teeth called the file and an opposing forewing with a scraper. When the file moves across the scraper, vibrations reverberate across the wing – the song of the katydid. The common true katydid, Pterophylla camellifolia, creates an amplification chamber by bowing its forewings to help resonate its call. The result is one of the loudest and most easily recognized of all katydid songs.

So, if the guys are singing their hearts out, female cicadas and katydids must be able to hear their songs, right? Right! Both male and female cicadas have membranes called tympana on their abdomen that enable them to detect vibrations. The auditory organs or “ears” of katydids are located inside chambers of the front of their forelegs. How strange. As the dreadfully hot summer day transitions to evening, listen for the calls of the dusk singing cicada and enjoy his attempts to woo a mate in the treetops. And as twilight transitions to dark, when the songs of cicadas’ end, soon will begin the chorus of the katydids, serenades of six-legged summer romances.

Acknowledgements

“Songs of Insects” by Lang Elliott and Wil Hershberger, the wonderful Songs of Insects website, and “The mechanics of sound production in Panacanthus pallicornis (Orthoptera: Tettigoniidae: Conocephalinae): the stridulatory motor patterns” by Fernando Montealegre-Z and Andrew C. Mason were used as references for this episode. Special thanks to Jen Franciotti for providing the inspiration for this episode.  

To hear the song of one of our local dusk singing cicadas, the Northern Dusk-singing Cicada, Megatibicen auletes, please click on the following link: http://songsofinsects.com/cicadas/northern-dusk-singing-cicada

To hear the song of one of our local nighttime chorusing katydids, the Common True Katydid, Pterophylla camellifolia, please click on the following link: http://songsofinsects.com/katydids/common-true-katydid

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 “Where are the butterflies?” Somewhat panicked questions like this started arriving several weeks ago and they don’t seem to want to go away. At first I was reluctant to acknowledge another concern in a year rife with uncertainty surrounding murder hornets, COVID19, and social unrest. Last week after a miserable showing of swallowtails at my butterfly magnet, also known as cup plant (Silphium perfoliatum), I shared the butterfly worries with several distinguished colleagues who confirmed that, yes, some butterflies were indeed scarcer this year in their gardens too. What a contrast to the summer of 2019, which seemed like butterfly nirvana with more than two dozen swallowtails nectaring at the same time on the cup plant in the front flower bed. This year, the butterfly magnet attained a paltry 3 swallowtails at any moment during the same week in which almost three dozen were sighted last year.

So, what gives with the butterfly drought? We know that changes in land use patterns associated with urbanization are responsible for dramatic losses in several insect species, including butterflies, in cities around the world. However, declines in the abundance of butterflies from one year to the next are often linked to more immediate ecological events. There are several key drivers of insect abundance. One important determinant of insect abundance is weather. In previous episodes we met a pair of invaders from the south, harlequin bugs and kudzu bugs. We have learned that as winter temperatures dip into the low teens and single digits it is simply too cold for these rascals to survive in Maryland, and their populations persist only in warmer redoubts further south. A second vital factor for insect survival is, of course, food. Changes in insect populations related to food resources are generally termed bottom-up effects. Part of the explanation for declines in monarch populations in North America are linked to reductions in populations of milkweed plants critical for larval survival. Moreover, scarcity of high quality nectar sources necessary to sustain adults as they migrate to overwintering hideaways, survive winter’s chill, and sally forth in late winter and early spring to colonize breeding grounds may be reducing populations.  A third major factor affecting insect populations, known as top-down effects, stems from Mother Nature’s hit squad of predators, parasites, and pathogens attacking, consuming, or infecting their victims. Long-term suppression of gypsy moths resulted when scientists reunited a fungal pathogen, Entomophaga maimaiga, from Asia with this killer of oak trees. This widespread pathogen helps keep gypsy moth at bay throughout much of its range.

How does all this relate to missing butterflies? Most notably scarce are several of large swallowtail butterflies including eastern tigers, black swallowtails, and spice bush swallowtails we visited in previous episodes. Butterfly experts suggest that some of these large swallowtails may have been fooled by some exceptionally warm weather in February followed by a rainy, chilly, and in some places frosty March, April, and May. Freeze warnings, frost, and record cold temperatures were recorded in several locations in Maryland in early May. Perhaps a few late season frosts took a toll on these beauties. On the bottom-up side of things, some think that drought stress in late summer and early autumn of 2019 may have reduced the quality of food resources for caterpillars as they completed development, thereby reducing their numbers or perhaps reducing chances for survival of pupa about to face winter’s wrath. Some have suggested that a really good year last year for some caterpillars translated into higher numbers of parasitoids and predators. In previous episodes we met rapacious caterpillar killers like wheel bugs and spined soldier bugs. We also know that many vertebrate predators, including insectivorous birds such as chickadees, depend on caterpillars for their survival. When numbers of caterpillars increase, so too do the numbers of these birds. While swallowtails have been scarce this year, I have never enjoyed as many blue jays, cardinals, wrens, and chickadees zooming around the yard as I have this spring and summer. Perhaps a bounty of caterpillars in the spring of 2019 translated into greater numbers of predators and parasitoids that put a damper on populations of some of our butterflies this year.

Swallowtails and some other butterflies seem unusually scarce in the DMV this spring and early summer. Unusual weather including late spring frosts, poor quality food resources last autumn, and mortality related to predators and parasites may have conspired to reduce their numbers.

Should we fear that a scarcity of swallowtails in 2020 portends a pending butterfly apocalypse? Nah, I don’t think so. Many other species of butterflies appear to be doing just fine. Silver spotted skippers and their kin arrived in my garden right on schedule in great numbers, as did cabbage butterflies. Peregrinations along the C & O Canal this spring and summer revealed zebra butterflies in good numbers and doing just fine. However, scientists warn that in the long term issues such as urbanization and climate change, including bizarre and severe weather patterns, spell trouble for many species of plants and animals, including insects. But as I finish writing this episode and look out the window to the cup plant, I see four tiger swallowtails getting their carbohydrate fix. Maybe upcoming broods of swallowtails will be bigger and better than their predecessors.

Acknowledgements

Bug of the Week thanks science writer, butterfly guru, and keeper of the Lep Log Rick Borchelt  for his insights and observations of butterflies throughout the region. Many thanks to colleagues in the Department of Entomology, especially Karin Burghardt and Leo Shapiro for providing references and helping clarify several points discussed in this episode. The following fascinating papers were consulted: “Western Monarch Population Plummets: Status, Probable Causes, and Recommended Conservation Actions” by Emma M. Pelton, Cheryl B. Schultz, Sarina J. Jepsen, Scott Hoffman Black and Elizabeth E. Crone; “Multiscale seasonal factors drive the size of winter monarch colonies” by Sarah P. Saunders, Leslie Ries, Naresh Neupane, M. Isabel Ramírez, Eligio García-Serrano, Eduardo Rendón-Salinas, and Elise F. Zipkina; “Declines and Resilience of Communities of Leaf Chewing Insects on Missouri Oaks Following Spring Frost and Summer Drought” by Robert J. Marquis, John T. Lill, Rebecca E. Forkner, Josiane Le Corff, John M. Landosky and James B. Whitfield; and “Nonnative plants reduce population growth of an insectivorous bird” by Desirée L. Narango, Douglas W. Tallamy, and Peter P. Marra.

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I really don’t have anything against beetles. In fact, beetles and I go back a long way as I studied many awesome leaf beetles in graduate school. However, butterflies, especially monarch butterflies, are a real delight and like many naturalists, I anxiously anticipate their return each year and celebrate their arrival. Two weeks ago the vanguard of what I hope will be a swarm of monarchs arrived and began poking around my milkweeds. Unfortunately, in advance of the monarchs, another hungry milkweed connoisseur moved into my butterfly weed patch well in advance of the monarchs. Milkweed leaf beetles are relatives of other members of the chrysomelid clan, a large group of beetles that includes dogbane leaf beetles, Colorado potato beetles, and three-lined potato beetles we met in previous episodes. Adults and larvae of this striking insect eat leaves of common and swamp milkweeds growing wild in meadows, and also butterfly weeds running rampant in my perennial beds. Adult beetles are voracious feeders and after colonizing my butterfly weed, they quickly removed large slices of leaves. Milkweed leaf protein is translated into batches of eggs inside the ovaries of females. About a week after eggs are laid, rotund orange beetle larvae hatch and graze night and day.

Tiny orange jellybean-like eggs on the leaves of my butterfly weed soon hatch and release rotund leaf beetle larvae intent on devouring milkweeds. Adult milkweed leaf beetles are large enough and apparently scary enough to displace small monarch caterpillars as they dine on milkweed leaves. Fortunately, butterfly weeds are prolific and there should be enough to go around for all of the insects that make a meal of milkweed.

One curious and somewhat disturbing habit of milkweed leaf beetle neonates is to go cannibalistic after hatching. Yes, some early hatchers perform the ultimate act of sibling rivalry and eat their unhatched brothers and sisters. Yikes! After starting life as meat eaters, the cannibals and their surviving siblings settle in to a vegan life style, consuming milkweed leaves before moving to the soil to pupate. In a few weeks, a fresh batch of adult beetles will emerge and initiate new conquests on my beleaguered butterfly weeds. As autumn approaches, the season’s last batch of adults fatten up on milkweed leaves before finding a protected refuge somewhere in my garden to spend the winter. As you can see, milkweed leaf beetles sport the same orange and black mien worn not only by the monarch, but also by milkweed tussock moths and milkweed bugs we visited in other episodes. This cabal of milkweed feeders has evolved the ability to thrive on milkweeds despite the presence of noxious heart poisons called cardiac glycosides found in the cells and sticky white sap of the milkweed plant. In some species like monarchs, these compounds are retained during the transformation of caterpillars into adult butterflies. Cardiac glycosides found in the wings of monarchs are known to cause severe digestive distress to avian predators. These compounds help protect monarchs from disappearing down the gullets of visually gifted predators like birds that regularly prey on caterpillars, butterflies, and beetles. Conspicuous orange and black colors worn by members of the milkweed gang serve as a reminder of a potentially nasty gastronomic misadventure to experienced birds and other predators that may have attempted to make a meal of a milkweed muncher. Fortunately for the monarch, butterfly weed is prolific and I hope there will be enough for everyone if and when the monarchs arrive in force.

Acknowledgements 

The delightful book “Secret Weapons” by Thomas and Maria Eisner and Melody Siegler, and the articles “Community-wide convergent evolution in insect adaptation to toxic cardenolides by substitutions in the Na,K-ATPase” by Susanne Dobler, Safaa Dalla, Vera Wagschal and Anurag A. Agrawal, and “Cannibalism and Kin Selection in Labidomera clivicollis (Coleoptera: Chrysomelidae)” by Kathleen R. Eickwort were used to prepare this episode.

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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 my first image of a male cicada killer and a somewhat panicked inquiry wondering if this might be the vanguard of dreaded murder hornets ready to invade the DMV. Relax, male cicada killers are harmless to humans but not so to dog day cicadas. This week, let’s learn a bit more about these awesome wasps from excerpts of an episode of Bug of the Week posted a couple of years ago. Cicada killers kill cicadas as a food source for their young. During the daytime, female cicada killers hunt prey in the treetops where dog day 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

Recently, 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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