Missing bugs of the week: Swallowtail butterflies, Papilionidae

 “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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Spotted beebalm, scarlet beebalm, and wild bergamot, these members of the Monarda clan are some of my absolute favorite perennial landscape plants. Why? By providing rich nectar rewards, these delightful natives are magnets for an astounding array of beneficial animals ranging from hummingbirds and gold finches to butterflies, bumble bees, hover flies, and myriad predatory and parasitic wasps. I have watched the summer parade of interesting and beautiful insects visiting Monardas for hours over a cup of coffee on sunny summer mornings.

But every year, there is foul-play afoot in my flower beds. Sometime in the latter days of May and early days of June, just as the bergamot is prepping to bloom, developing flower buds and their attendant sepals become shredded and riddled with holes. Close examination of the buds reveal tiny black pellets lodged in the nooks and crannies of the flower heads. Now, to bug geeks, tiny black pellets usually are a sign of insect activity. Said pellets are actually the excrement, a.k.a. frass, of caterpillars feeding within the flower buds. Some further poking around the nascent blossoms revealed small creamy colored caterpillars hiding in the axils of sepals and at the bases of florets. While identification of small caterpillars presents a challenge even to seasoned entomologists, identification of adult moths and butterflies is way easier. A more extensive search of the bergamot patch revealed a rather pretty raspberry pyrausta moth, a member of the crambid moth clan. Crambid moths, also known as snout moths, are named for the elongated mouthparts protruding from the front of their head. Many bore into the stems of grasses and other monocots and some, such as the European corn borer and sod webworm, are serious agricultural and lawn pests. Just one or a few of these caterpillars feeding within a developing flower bud are sufficient to all but ruin its floral display.

Here is the dilemma. For many herbivores in my landscape, the death sentence is commuted under a live-and-let-live policy with the belief that even pests will become food for other insects or birds higher in the food web. However, in the case of the raspberry pyrausta, lack of intervention translates into few or no blossoms on Monardas and few or no resources for pollinators, predators, and parasitoids dependent on nectar and pollen for their activity and survival. So, in this case the caterpillars gotta go to make way for the beneficial insects. Ridding the blossoms of caterpillars is fairly easy to do. As flower heads begin to form in late spring and early summer watch out for holes in leaves, feeding damage to developing florets, and small black frass pellets accumulating in the axils of leaves and sepals. Carefully search the flower head and when you locate the caterpillar, simply crush it. If you don’t like touching insects, don a pair of rubber gloves and do the deed. Mechanical destruction of the pest is foolproof and works well in small patches.

While some blossoms on my bergamot look fine, many are ravaged. This culprit is a small caterpillar feeding in the flower head. Chewed florets, holes in leaves, silk, and pellets of frass are telltale signs of the caterpillar. Regular inspections and crushing caterpillars when you find them will help keep your blossoms looking fine.

For larger plantings, you could consider using an insecticide listed by the Organic Materials Review Institute (OMRI) for controlling caterpillars. These insecticides have been reviewed by scientists and approved for use in the production of organic food crops. Two of my favorites contain the active ingredient Bacillus thuringiensis kurstaki (Btk) or spinosad. Btk is derived from a common soil microbe and it works well on many species of caterpillars. If you grow milkweeds as a source of food for monarch caterpillars in your flower beds, take care not to spray Btk on your milkweed lest you poison any resident monarch larvae. Some brands of spinosad will also carry the OMRI stamp of approval and they work well on caterpillars. Spinosad is also a product of a soil microbe. This molecule attacks the nervous system of insects. But be careful with spinosad, as it is highly toxic to bees. If other plants in your garden are in bloom or are about to bloom avoid drift that might contact and harm charismatic pollinators. Use the same caution with Monarda. The pyrausta will be present in the early formation of flower buds but as florets form and mature, avoid using spinosad as bloom time approaches and certainly when flowers are in bloom. Many snout moths have multiple generations and in my experience the raspberry pyrausta is no exception. I have crushed several crops of caterpillars in the flower buds and just the other day, a few more adult moths dared to flit around my flower bed.

For a bug geek, watching the sunrise on a warm summer morning while sipping some coffee and squashing some caterpillars is not a bad way to start the day.  

Acknowledgements

We thank Dr. Shrewsbury for providing the inspiration for this episode as well as snapping some photos and crushing caterpillars to save the monardas from marauding caterpillars.

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One of the upsides of the ongoing COVID-19 pandemic is a notable increase of folks enjoying time outdoors walking, cycling, and visiting at social distances along neighborhood streets. One steamy morning last week as I circled the block, I noticed surprising numbers of rather large bees buzzing about mailboxes along the streets. Bees interested in postal delivery? A closer look told the tale. Let’s start with the mailbox. If your mailbox is like mine, it rests atop a wooden post some four feet or so above the ground. Over the years the post supporting my mailbox has become home to an occasional colony of carpenter bees. Year after year sometime in May the carpenter bees reliably return to the mailbox post. Males perform aerial battles for dominance of the mail box territory and their mates chew perfectly round holes in the mailbox post, entrances to brood chambers for their young. But in July, as carpenter bee activity wanes, activity around the mailbox post is supplanted by another type of bee. The aerial acrobats now performing near mailboxes are giant resin bees, exotic colonists from Asia first reported in the United States in North Carolina in 1994. In addition to their native Asian range that includes China, Japan, and South Korea, giant resin bees have been discovered in Italy, France, and Switzerland in Europe. In North America they range from Canada to Alabama in most states east of the Mississippi and have been reported in almost all counties in Maryland.  

Giant resin bees belong to a family of solitary bees known as Megachilidae and are kin to mason bees and leaf cutter bees we met in previous episodes. Like mason bees, each female bee is reproductively active and therefore dissimilar to social bees like honey bees and bumble bees that have a queen. Their presence near a mailbox post riddled with carpenter bee galleries is no mystery. Despite sporting powerful jaws, the potency of which I discovered after handling one, giant resin bees do not excavate galleries in wood. Their sharp jaws are simply not strong enough to do so. Instead, they rely on existing galleries to create a home for their brood. Abandoned galleries of carpenter bees provide perfect chambers to colonize and raise their young. While male giant resin bees spend time defending territories and chasing each other about, female bees gather plant resins to line the inside of the gallery. After each chamber is properly prepared, females collect pollen on fine hairs called scopa on the undersides of their abdomens, return to their galleries, and create pollen balls inside the brood chamber. Eggs are laid on the pollen balls, which serve as the food source for the developing larvae.

On my neighbor’s mailbox post a male giant resin bee arrives to stand guard. When not performing aerial antics, male giant resin bees can be found fanning their wings around co-opted carpenter bee galleries. Does he await the appearance of a lovely lady bee while shooing away other potential suitors?

The ecological impact of these nonnative bees is still largely unknown. They have been observed foraging on several imported plants from their native range including golden rain tree, Koelreuteria paniculata, glossy privet, Ligustrum lucidum, kudzu, Pueraria lobata, and Japanese pagoda tree, Sophora japonica. There is some concern that they may commandeer nesting sites of our native carpenter bees, but the true magnitude of this effect is still unknown. With the abundance of human made habitat for carpenter bees, there may be enough wood to go around for all wood-nesting bees. Who knows? Nonetheless, these goliaths of the solitary bee world are here to stay and they make an interesting study on a walk around the block on a warm summer morning.  

Acknowledgements 

We thank our gracious neighbors who allowed us to photograph giant resin bees on their mailbox post early one morning and our friends at Woodend Sanctuary for allowing us to film their giant resin bees. The interesting article “Invasive Megachile sculpturalis in Upstate New York” by Robert G. Laport and Robert L. Minckley was consulted in preparation of this episode.  Bee guru Sam Droege provided the fantastic image of a female giant resin bee featured in this episode.

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Through no fault of their own, white-tailed deer are a major pest of ornamental plants in our suburban and rural landscapes. It is estimated that in the US, more than 20 million deer share the land with us. When I see a dozen or so bedding down in my backyard, I think most of these rascals live in Columbia, Maryland. Long gone are the wild predators, mountain lions and wolves, that once kept burgeoning deer populations in check. Encroachment of human development on natural habitats put deer in contact with humans and their gardens. The grazing pressure of deer in my neighborhood has defeated all attempts at growing unprotected vegetables. During the winter, my pansies were pillaged and my once glorious azaleas were reduced to skeletal pickets of denuded branches presenting a few sad blossoms this spring. Small saplings bear the scars and deformities dealt by young bucks removing velvet from their antlers. The growing tips of my hopeful sunflowers and blueberries are but a memory. With all the undesirable changes deer bring to the suburban landscape, what is the upside of this pariah?

One answer to this question appears in the final resting place of recently expired deer, the deerly departed so to speak. Several years ago while walking a field not far from a roadway traversing Etchison, Maryland, I noticed the earthly remains of a white-tailed deer resting in the tall grass, no doubt the unfortunate participant in an encounter with a vehicle on the nearby road. Upon closer inspection, I discovered a well-developed ecosystem of necrophagous insects making the most of the decaying bounty provided by the deer in its final act. Among the most prominent and abundant of these flesh eaters was Oiceoptoma noveboracense, commonly known as the margined carrion beetle. Along with flies and other species of beetles, carrion beetles provide an important ecosystem service by recycling the protein found in the flesh of dead animals. Carrion beetles are not usually the first to arrive at the carcass of a dead thing. This honor belongs to blow flies which often discover a body within minutes of its demise. Once colonized by blow flies, a dead animal will soon be writhing with maggots of flesh-eating flies. Maggots are an important source of food for adult carrion beetles. As they graze on the fleshy bounty, adult beetles occasionally deposit eggs in the soil near the carcass. Eggs soon hatch into larvae, youthful champions at consuming shreds of protein-rich flesh and internal organs of the deceased. By the time I happened across the deer, hundreds of beetle larvae were enjoying sustenance and shelter from the helpful deer.

In a previous episode we met bess beetles, one of the champion insect recyclers of wood. But in the wild more than wood is available for repurposing. Dead animals play an important role in food webs as rich sources of nutrients for the necrophagous species, eaters of the dead. Watch how a bountiful supply of deceased white-tailed deer reenters food webs with the assistance of flesh-eating carrion beetles.

A more recent discovery of a disarticulated deer along a bike trail revealed the carrion beetle’s dogged ability to remove even the last shreds of meat from a bone. After feeding as larvae and molting several times, larvae move to the soil to pupate. A bit later in summer, fresh adults will emerge from the soil and await the arrival of more dead animals ready for recycling. Due to their affinity for certain types of habitats, their patterns of seasonal appearance, and their geographic distribution, Oiceoptoma beetles can be useful in helping crime scene investigators solve homicides. Uplifting encounters with deceased white-tailed deer provided some succor to the ill will engendered by these habitat destroying herbivores. To bring more crime solving, flesh recycling beetles into the world is surely a noble final deed for the oft maligned white-tailed deer. 

References

Many thanks go to Kelly for allowing me to wander his fields and to Dr. Shrewsbury, who spotted the deer skull along the Western Maryland Rail Trail, for inspiring this episode. The delightful reference “The Carrion Beetles (Coleoptera: Silphidae) of Nebraska” by Brett Radcliffe was used as a resource.

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Last month we learned how aphids can wind up with a hole in their rear end courtesy of tiny parasitic wasps that turned them into mummies. This week we see how aphids can meet another gruesome end in the jaws of aphid lions. With ample rainfall and favorable temperatures, the lush growth on trees and shrubs continues to generate healthy populations of aphids on many garden plants. A week or so ago, on a dynamite pollinator attractor called Silphium perfoliatum, a.k.a. cup plant, I noticed a fine crop of aphids happily sucking sap on the underside of leaves. The thought of giving these gals (many aphids at this time of year are a “ladies only” society due to parthenogenetic reproduction) a squirt of insecticidal soap to quell their numbers ran through my mind for a brief moment. Fortunately, upon closer inspection of the festivities I spotted a murderous contingent of Mother Nature’s hit squad nearby, brown lacewing larvae. Brown lacewings are close kin to debris carrying green lacewings we visited in a previous episode.

Green and brown lacewings go by the colorful common name of aphid lions. Here’s why. Adult lacewings are attracted to fragrant odors emanating from plants infested with aphids. As they feed on plant sap, aphids produce a waste product called honeydew. The honeydew is a sweet concoction of sugars, amino acids, and other compounds. As this sticky goo degrades, telltale odors waft from the plants. Female lacewings cruising the landscapes in search of food for themselves and their babes sense aphid-related odors. The scent is like the smell of burgers and fries to a fast food junkie and sends a signal to the mother lacewing that “dinner is served”. Upon arriving on a plant, if the proper cues are present, the female green lacewing touches her abdomen to the surface of a leaf and draws out a thin strand of protein. At the tip of this protein stalk, she deposits a single egg. Why she goes to this trouble is not entirely clear. Perhaps, by placing the egg on a stalk, hungry predators including other lacewing larvae are less likely to snack on the tasty egg. Brown lacewing mothers seem to eschew this behavior and deposit their eggs directly on the surface of the leaf. After hatching, the tiny larva shinnies down the stalk and begins its search for food. If mom was clever and placed the egg in the right spot, a smorgasbord of aphids awaits nearby.

Aphid lions to the rescue! Last week my cup plant was loaded with aphids. Brown lacewing larvae came to town and now it’s so long aphids. When aphids appear, before you spray take a moment to see if some of Mother Nature’s hit squad, like brown and green lacewing larvae, have arrived to help.

Aphid lions have powerful, sickle-shaped jaws that grasp their prey. Once attached to the aphid, a pump in the aphid lion’s head is activated and the liquid life is sucked from the hapless victim. Aphid lions are reported to devour 200 aphids per week and several hundred during the course of their development. After shedding its skin twice to grow, the aphid lion spins a white cocoon and attaches the cocoon to the plant. Within this silken orb the transformation from alligator-like larva to pupa to winged adult takes place. After a few weeks in the cocoon, the beautiful adult lacewing emerges. The adult green lacewing has fantastic green or golden eyes and dozens of veins running through its wings, hence the name lacewing. Adult lacewings eat nectar and pollen and honeydew produced by aphids and other sucking insects. In addition to feasting on aphids, voracious lacewing larvae eat a variety of prey including caterpillars, spider mites, lace bugs, beetle larvae, and eggs of many kinds of plant pests. They are highly beneficial. Aphid lions can be purchased commercially and released on plants to help reduce pest populations. These fierce predators have been used to reduce pests with some success in agricultural crops such as cotton and strawberries and to reduce mealybugs on houseplants indoors and lace bugs on azaleas in landscapes and nurseries. As I watched aphid lions devour aphids with remarkable gusto, I wondered what our world would be like if aphid lions were the size of the German Shepherd next door.  

Acknowledgements

The interesting references “Handbook of Biological Control” by Thomas S. Bellows and T.W. Fisher, and “Biological control in specific crops: Woody Ornamentals” by Paula Shrewsbury and Michael Raupp, were used to prepare this episode.

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