Colorful barklice, most likely Cerastipsocus venosus, have been seen in many counties in Maryland this year. Photo credit: Cathy Keifer
Have you ever opened a musty old book and spotted a minute brownish insect skittering across a page? Yep, this was a close encounter of a booklouse kind. Booklice are often found amongst forsaken books and magazines where they consume starchy materials like the glue used in bindings. But remember, books have only been around for a measly few millennia at best and the booklouse clan has been on the planet for some 250 million years. So what were those tiny starch eaters doing all that time?
Wingless nymphs and winged adults are often seen in large aggregations on the bark of trees. Photo credit: Rachel Rhodes
Over the past week or two several Bug of the Week enthusiasts sent images of psocids hanging out on the bark of trees. The wild cousins of booklice are known as barklice. They are commonly found on the bark and foliage of trees and shrubs where they consume lichens (symbiotic partnerships of algae and fungi), algae, and other organic matter. This natural detritus sustained Psocids for millennia until people kindly began supplying starch-based foods such as book bindings, glue, and grains. Psocids do not harm or damage plants. Recently, I joined a group of arborists inspecting trees and shrubs for pest problems around San Francisco where cool morning fog punctuated by brilliant afternoon sunlight provides excellent conditions for the growth of lichens and algae. Several plants we scrutinized had leaves infested with tiny insects that at first glance appeared to be pesky aphids. Closer inspection revealed these to be small colonies of psocids.
Psocid (barklouse) nymph/adult 2018 - YouTube
Observe the wing buds on the back of this barklouse nymph. Soon it will molt into a winged adult that may be easily disquieted by bristles of a paint brush.
Beneath silken webs on the undersides of holly leaves, I often encounter jelly-bean shaped eggs of barklice.
Psocids can be easily distinguished from aphids with the aid of a hand-lens. Psocids have large heads with chewing mouthparts and aphids have rather small heads bearing tubular sucking mouthparts. On the campus of the University of Maryland I often find adult and juvenile bark lice nestled beneath the broad evergreen leaves of native and non-native hollies. Barklice on hollies are sometimes associated with sap-sucking insects like soft scales. Honeydew from the scales forms the substrate for the growth of sooty mold, which may be a source of food for resident barklice. From specialized glands in their mouths barklice spin silk into delicate webs. Clusters of jelly-bean shaped barklice eggs often rest beneath these silken mats. Dense populations of barklice can create silken shrouds that encase entire branches and trunks of trees. I witnessed a memorable barklice veil on a hawthorn tree at a rest stop along I-95.
At a rest stop on an interstate, branches of a small tree were shrouded with barklice silk.
While most barklice are harmless, some are important pests infesting grains and cereals. However, for the most part these tiny and sometimes colorful insects are simple members of Mother Nature’s recycling team.
Bug of the Week thanks Rachel Rhodes and Cathy Keifer for providing images and inquiries that served as the inspiration for this episode. We thank Treemasters Tree Service for a peek at California psocids and the Maryland Biodiversity Project for aid in identifying psocids in this episode.
Beneath a leaf, a pale green assassin bug lays her eggs. Photo credit: Rebeccah Waterworth
Greek mythology has it that the lesser deity Zelus, who, with his brother Nike, stood by Zeus’ side and enforced his edicts, embodied the traits of envy, jealousy, and zeal. While watching assassin bugs, one has to admire and perhaps even envy their stealth and cunning in stalking and capturing prey. Witness the mighty assassin bug known as the wheel bug as it dispatches a hapless caterpillar:
Wheelbug stalks caterpillar - YouTube
After sizing up its prey, the wheel bug strikes with astonishing speed.
A small wasp falls victim to the sticky legs and hungry beak of Zelus.
Not all assassin bugs rely on sheer power to subdue their victims. In a previous episode we met the milkweed assassin bug Zelus longipes. Hiding motionless in a flower-head or slowly moving about a leaf, it employs hairs on its front legs known as sundew setae to snare its prey. Specialized glands produce a highly viscous and sticky substance that coats these specialized hairs. Small prey items like flies or wasps that might otherwise escape an unarmed, clutching foreleg become stuck in this gummy secretion and cannot escape. Once captured, the prey is impaled with a hungry beak that injects proteolytic enzymes, predigesting the contents of the victim. The liquefied contents of the prey are sucked into the digestive tract of the assassin bug with the aid of a tiny muscular pump in the assassin bug’s head.
This Zelus nymph will soon earn it wings.
Older Zelus nymphs and adults are able to produce the sticky goo used to capture prey but a clever study demonstrated that hatchling nymphs lacked the sticky droplets used to snare prey. However, mother Zelus is a good provider. When she deposits her eggs on the surface of a leaf, she leaves behind a coating of viscous fluid on each egg. One of the first tasks undertaken by the hatchling nymphs is to gather the sticky fluid and spread it onto their legs. Armed with an innate calling to capture prey and sticky legs to seal the deal, young Zelus embark on a life of predation amongst the flowers and foliage in the garden.
Tiny predators with sticky legs evoke awe in me.
Assassin bugs (Zelus luridus) hatching - YouTube
Zelus nymphs hatch from barrel-shaped eggs deposited by their mother. Watch closely as hatchlings dab the egg mass with their legs to collect the sticky fluid used to help them capture prey. Video credit: Rebeccah Waterworth
Bug of the Week thanks Rebeccah Waterworth for providing Zelus eggs, video and images used in this episode and for the inspiration behind this story. The fascinating article “Observations on the sticky trap predator Zelus luridus STÅL (Heteroptera,Reduviidae, Harpactorinae), with the description of a novel gland associated with the female genitalia” by C. Weirauch provided insight into the nature of this zealous predator.
Whether upside down or right side up, the American Painted Lady is one gorgeous butterfly.
When not actively feeding on leaves, American Painted Lady caterpillars hide in silken shelters spun around leaves of their host plant.
Over the past several weeks we have visited some true tormentors of humankind, including floodwater mosquitoes, ticks, lanternflies, and stink bugs. This week we turn our attention to one of the real treasures of our urban wild, the enchanting American Lady butterfly, also known as the American painted lady. Last week while visiting my favorite familial B & B in Long Valley, NJ, the lady of the house asked me about some peculiar silk covering small clusters of leaves on her dainty licorice plant. Closer inspection of these silken retreats revealed a beautiful spiny caterpillar bedecked in creamy intersegmental bands with white dots on black and red bands encircling the abdominal segments - the larva of the American Lady butterfly. Awesome!
Licorice plant, Helichrysum petiolatum, belongs to the family of plants known as the Asteraceae, the sunflower family. Discriminating American Lady butterflies choose everlasting, ironweed, burdock, pussy-toes, and related species of the Asteraceae in addition to licorice plant as the food source for their young. These ladies are extreme voyagers, departing their permanent residences in the southern United States, Mexico, and Central America each year to take wing in monarch-like migrations that reach the northern United States, southern Canada, several Caribbean islands, and even Europe. Tiny eggs deposited on host plants hatch into very hungry caterpillars capable of consuming remarkable amounts of foliage as they gain more than a thousand times their birth weight during the course of development.
American painted lady caterpillar feeding - YouTube
During the course of development, it is not unusual for moth and butterfly larvae like this American Painted Lady to gain more than a thousand times their birthweight.
Nestled between two leaves of licorice plant, the chrysalis sets the stage for metamorphosis from caterpillar to butterfly.
Gossamer shelters of silk spun around leaves serve as a refuge from the searching eyes of hungry predators as caterpillars feed and develop. Transformation from larva to adult takes place in a tawny chrysalis suspended from vegetation. As you will see from the images, adult butterflies are drop-dead gorgeous. They nectar on several common hosts found in meadows and gardens including dogbane, goldenrod, marigolds, milkweeds, and vetch. In their permanent southern homes three or four generations occur annually, but in southern New England only two broods are usually observed. Plant some pussy-toes or licorice plant and you too may be visited by these remarkable American Ladies.
Bug of the Week thanks the ever-gracious Sheri and Gordon for sharing their licorice plants and caterpillars for this story. Rebeccah Waterworth provided interesting insights into the migrations of American Ladies, and the wonderful references “Caterpillars of Eastern North America” by David Wagner and “Butterflies and Moths of North America” provided details for this episode.
Legions of inland floodwater mosquitoes like this egg-filled Aedes vexans will soon make their presence known as they seek human victims on warm summer nights.
Late spring and early summer of 2018 witnessed record rainfall in several parts of our region, flooding ill-fated Ellicott City and swamping low-lying lands around the mighty Potomac and Patuxent Rivers. Some hoped these rains were a “one-and-done”, but persistent rains and saturated soils have created long-standing puddles in low lying areas of lawns, parks, and woodlots and in swales along verges of roadways. These standing water sources are the perfect breeding site for legions of floodwater mosquitoes including the nefarious inland floodwater mosquito, Aedes vexans. Found throughout many parts of the world, Aedes vexans is an important nuisance pest in North America, Europe, and parts of Asia and Africa. It also vectors a variety of debilitating, potentially lethal pathogens of humans and pets. It has been implicated in the transmission of Eastern Equine Encephalitis, a deadly disease of humans and horses. It also transmits dog heartworm, a nasty tiny roundworm that invades the heart of a dog. Fortunately, humans do not contract this disease but this parasite extinguished the life of my childhood dachshund.
Unlike the invasive Asian tiger mosquito, a tormentor during daylight hours, Aedes vexans extends a day of mosquito misery by seeking hosts and biting people at dusk. As with the rest of the blood-feeding mosquito clan, it is only the females that seek blood. Protein in animal blood is transformed into eggs within the ovaries of the mosquito. However, mosquitoes cannot live on protein alone. The energetic demands of searching for hosts and dodging hungry predators and murderous humans requires carbohydrates. The sources of these sugars are nectar from plants and other natural sweets such as honeydew produced by sap-feeding insects like aphids. Protein requirements of male mosquitoes are far less than those of the ladies, hence, they do not bite animals but obtain their nutrients from nectar and honeydew. Who knew that dastardly mosquitoes were also beneficial pollinators?
Watch as this female Aedes vexans tanks-up on sugar from a droplet of honey. The elongated proboscis used for sipping honey or nectar is the same weapon used to suck blood from humans and other animals.
Aedes vexans mosquito feeding - YouTube
Aedes vexans survives winter as eggs deposited on moist soil in areas prone to flooding. When spring rains arrive and low areas fill with water, eggs hatch and larvae feed on the biofilm of microbes festooning submerged vegetation. In the mid-Atlantic region, mosquito larva called wrigglers can be found from May until October and with a steady recharging of breeding sites thus far this year, we can expect continued production of these vexing vampires for the near future at least.
Mosquito larvae feeding 2018 - YouTube
In this floodwater pool near the edge of a forest, mosquito larvae cruise the water column and dine on the biofilm covering submerged leaves and microbes suspended in the water.
Protecting yourself from mosquito bites
Protect yourself from aggressive biters by wearing light-weight, long-sleeved shirts and pants when working outdoors. You can purchase clothing pretreated with the mosquito repellent permethrin. I have worn this clothing in tropical rainforests where mosquitoes were ferocious and it really did help. Permethrin can also be purchased as a ready-to-use spray to treat clothing. Do not apply permethrin directly to skin and follow exactly the directions for use found on the label. Many insect repellents can be applied to exposed skin before you go outdoors. Some will provide many hours of protection, while others provide virtually none. The “gold standard” of mosquito repellents is the compound DEET. Higher percentages of DEET in a product generally result in greater levels and duration of protection but concentrations of 25 – 30 % should do the trick. Two alternatives to DEET contain the active ingredients picaridin or IR3535. These can also provide many hours for protection from mosquitoes.
In recent years many botanically-based products have come to the marketplace. Scientists discovered that wild tomato produces a compound, 2-undecanone, that prevents mosquitoes from landing on humans for many hours. Other products containing oils extracted from lemon eucalyptus, Corymbia citriodora, and products combining oils of soybean, geranium, and caster bean protect people from mosquito bites. Products based on citronella and other essential oils derived from plants vary greatly in repellency with average protection times ranging from 5 minutes to 2 hours. So, you may have to apply these products more frequently to be protected.
Questions always arise regarding the use of repellents on children. Repellents carry precautionary statements on their labels. Always read the label carefully and follow directions and precautions exactly. You should help children apply repellents and consult a pediatrician before applying any product to the very young. Some products state not to let children handle the product and even some botanically-based products warn against use on kids under the age of 3.
To learn more about insect repellents, please visit the following CDC and EPA websites:
At a residential home in the DMV, a pool of standing water breeds tens of thousands of inland floodwater mosquitoes. A single sample with this mosquito dipper holds hundreds of larvae and pupae soon to turn into adult mosquitoes ready to torment local residents. Image credit: Megan Fritz
To reduce the chances of mosquitoes breeding around your home, eliminate standing water by cleaning your gutters, dumping your birdbath twice a week, inverting your wheelbarrow and getting rid of water-filled containers. Those corrugated drainpipes that direct water from downspouts can also hold enough water to breed mosquitoes such as the Asian tiger. Installing drainpipes with slits or periodically removing pipes and draining them will help eliminate water where mosquitoes breed. If you find mosquito larvae in an aquatic water garden or a long-standing pool of water on your property, then you can use a product containing the naturally occurring soil microbe known as Bacillus thuringiensis israelensis, a.k.a. Bti, to kill larvae. Bti comes formulated in doughnut-shaped tablets that can be placed in water. If you have an uncovered swimming pool, with proper filtration and disinfection systems, it should not serve as a mosquito breeder. If your pool is covered and water collects in a non-porous tarp, then mosquitoes may breed in standing rainwater that collects in the cover. You should empty the cover regularly or treat it with a larvicide.
So, in this season of never ending rain, be on the lookout for mosquitoes as they will surely be looking for you.
Bug of the Week thanks Dr. Megan Fritz for providing inspiration and information for this episode and for mosquitoes used in its production. The interesting reference “Aedes Vexans (Meigen): An Old Foe” by Claudia M. O'Malley was used as a reference for this episode. To learn more about this mosquito, please click on the link below:
More closely related to a carpenter bee than a bumble bee, the earth mining bee, Anthophora abrupta, is an important pollinator of many flowering trees, shrubs, and herbaceous plants.
Several years ago along one of my favorite trails, a majestic old tulip poplar tumbled over exposing an impressive vertical root plate about four feet in diameter. Over the years, the exposed matrix of earth and roots has become the perfect site for several species of ground nesting bees to take up residence. Early one steamy morning last week while passing the fallen giant I was distracted from my reverie by loud buzzing coming from the root plate. Amidst the soil and roots a swarm of boisterous bumble bee–like insects cavorted, digging holes in the soil and performing aerial acrobatics.
A pair of lady miner bees busily ready their earthen tunnels in preparation for provisioning them with nectar and pollen, and depositing eggs within.
In previous episodes we met bumble bees and learned a bit about their societies and way of life. However, these bees did not conform to the bumble bee stereotype of workers sharing a colony with sisters performing the bidding of their mother, the queen. Each of these gals was clearly a standalone, excavating its own gallery in the soil independent of the shenanigans of its neighbor. Fortunately, the wizard of native bees, Sam Droege, set me straight as to who these fascinating ladies really were. Miner bees and digger bees belong to a clan known as anthophorid bees, a curious group that includes carpenter bees we met in previous episodes. Due to their distinctive pattern of black and yellow hairs and loud buzzing demeanor they are often mistaken for bumble bees. But in the miner bee world, every lady is a queen, each creating her own gallery in the soil. Tunnels in the soil may be five or more inches long and are lined with brood cells. After excavating these cells, female bees seal and waterproof each one with a glandular secretion. Cells are then provisioned with pollen and nectar, eggs are deposited, each cell is sealed, and then the tunnel is plugged with clay. The babes inside consume the nutritious larder, develop over the course of the year and emerge the following spring as adults. These handsome bees are important generalist pollinators and their host list includes plants in twenty families ranging from American persimmon to Virginia bluebells. According to Graham et al. 2011 they are “potential pollinators of many important crops including: cranberry, tomato, blackberry, asparagus, persimmon, clover and raspberry.”
Miner bees (Anthrophora) - YouTube
Amidst the clay and roots of a toppled tree, miner bees excavate galleries soon to be nurseries for their offspring. A close resemblance to bumble bees probably fools predators as well as folks unfamiliar with these interesting pollinators.
The Bee Wall at the University of Maryland is a great place to see marvelous mining bees in action. Image: Lisa Kuder
As a final thought to this episode, while many folks have a fear of bees, which maybe well-founded for those with allergic reactions, Anthophora abrupta is a very docile citizen of the bee world. My cameras were within centimeters of these beauties as I recorded this episode. Meanwhile, a group of youngsters and their parents stopped by the well-travelled trail in Columbia, Maryland to witness and enjoy these bees along with me. To enjoy some of these interesting solitary bees, keep your eyes open for muddy riverbanks or clay-caked roots of fallen trees where miner bees like to construct their homes, or plan a trip to the Bee Habitat Wall sponsored by Bug of the Week at University of Maryland’s Arboretum Outreach Center.
We thank Sam Droege for assistance in identifying bees and for providing information on their habitats and biology. Featured Creature fact sheet “Miner bee, Anthophora abrupta “by Jason R. Graham, Jamie Ellis, Glenn Hall, and Catherine Zettel Nalen of the University of Florida was used as a reference for this episode.
Bee flies like this Greater Bee Fly frequent meadows bustling with blossoms and are often confused with bees.
Pretty Anthrax georgicus devours larvae of ground dwelling tiger beetles as they develop in their earthen galleries.
This year and in springs past we visited interesting spring pollinators including honeybees, bumble bees, plasterer bees, carpenter bees, and mason bees. While exploring a meadow, I stumbled on swarms of busy pollinators darting among patches of dandelions and hovering near native wildflowers. One particularly frenetic insect appeared to be some kind of furry bee with a wickedly long tongue probing 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 honeybees 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.
Greater bee fly feeding - YouTube
Bee flies require huge amounts of carbohydrates which they obtain from nectar to power muscles used for flight. Watch as the Greater Bee Fly, Bombylius major, extracts nectar from a dandelion with its ridiculously long proboscis.
Don’t be surprised to see the Tiger Bee Fly, Xenox tigrinus, loitering on decks or siding infested with carpenter bees. Larvae of the carpenter bee are food for the larvae of this handsome fly.
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 the provisions left behind by the solitary bee, and then turn 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.
Distinct patches of black on the wings of Chrysanthrax cypris make it easy to identify this pollinator in the meadow.
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 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, such as tiger beetles, as well as baby bees. So bees beware, ‘tis the season of the bee fly.
The Master Naturalist Program of the University of Maryland provided the inspiration for this episode. 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.
Will this beautiful female Magicicada cassini live long enough to mate and reproduce, or will her early appearance in advance of the main brood doom her and her broodmates?
Temperatures were in the upper 80s two weeks ago as I trudged across campus for a review session with nervous students prepping for a final in biology. The sweltering, clammy calm of the afternoon was interrupted by a lonesome call of a male periodical cicada high in the top of a willow oak tree. With this announcement, the 2018 periodical cicada season was officially underway.
Cicada Brood X 2018 - YouTube
Holes in the ground, shed skins on leaves, and adults ready to ascend to the treetop… yep, cicada season is underway.
Homeowners around Columbia, MD sighted cicadas on foliage and plants last week. Photo credit: Nancy Perkins
In the intervening week, I received two reports confirming the arrival of adult cicadas in Bowie and Columbia, MD. A recent afternoon jog around the neighborhood in Columbia revealed shed skins on several majestic elms, oaks, and lindens, where hundreds of cicadas were spotted last year. Entomophiles are already awaiting the return of Brood X cicadas scheduled for 2021. Last year we had a sneak preview of this event in many neighborhoods in the DMV with the appearance of thousands of cicada “stragglers”. Stragglers are periodical cicadas that emerge “off cycle” in years prior to or after their major brood appears. Often, 17-year cicada stragglers appear four years prior to their expected emergence date; however it is possible for periodical cicadas to emerge several years earlier or later than expected. According to Cicada Mania, the most reliable source for all things cicada, historical records indicate that part of “the Big Brood”, Brood X cicadas, undergo a curious developmental phenomenon known as acceleration. Accelerations occur when a portion of a cicada brood emerges years in advance of the billions of cicadas comprising the bulk of their ginormous synchronous brood. Four year accelerations, including some associated with Brood X, have been observed in Washington DC, and in Chicago, Cincinnati, and other parts of the Midwest. In several areas, last year’s stragglers emerged in numbers sufficient to best hungry predators and survived long enough to reproduce and lay eggs. With any luck their progeny will emerge in spring some 17 years in the future.
Brood X stragglers have already been reported this year in Cincinnati, Ohio and Bloomington, Indiana. I think we can add Bowie and Columbia, Maryland to this growing list. However, after discovering a local Columbian cicada patch, I returned early one morning to find it had turned into a cicada killing field as mixed swarms of several bird species picked off scattered cicadas that had emerged overnight. You see, without millions of their broodmates to fill the tummies of hungry predators, these stragglers were likely doomed to perform the Darwin experiment: emerge prematurely and remove your genes from the population. Cicadas pay a heavy price by not following the rules of their ancient strategy of predator satiation, a plan that depends on an enormous synchronous emergence that simply overwhelms the capacity of predators to consume a tsunami of cicada prey. While I always root for the cicada, I fear numbers are too slim for cicada success this year.
Birds eating cicadas - YouTube
In the cicada killing fields, pileated woodpeckers seem to search a tree while a tufted titmouse enjoys a tasty cicada for breakfast in branches above.
The real deal brood of cicadas emerging in 2018 are those of Brood VII, the ill-fated Onondaga Brood. The range of this brood, which once occupied at least nine counties in the Finger Lakes region of New York State, has declined dramatically in recent decades. Experts fear it may be the next brood to go extinct, joining Brood XI that disappeared in Connecticut. Cicada Mania points to the usual suspects of habitat destruction due to agriculture and urbanization, habitat degradation due to several factors including pesticides, and natural events such as persistent floods that smother cicada nymphs in their subterranean lairs, as the underlying causes of these declines. Magicicada cassini, one of the major participants in Brood X, utilizes ash trees as a favored host for egg laying. Emerald Ash Borer, dastardly destroyer of more than 100 million ash trees in 20 states where cicadas are found, certainly hasn’t helped the plight of our periodical cicadas.
If you want to see periodical cicadas in all their glory, your best bet would be to head for the Finger Lakes region of New York near Rochester to have a look, maybe the last look, of these strange and magnificent creatures of Brood VII. Here in the DMV, keep your eyes and ears open for the next several weeks, and please participate in the citizen science project listed below to track these magical creatures. Happy cicada hunting!
CALL TO CITIZEN SCIENTISTS: we need your help! Cicada experts are attempting to map the distribution of these magnificent and magical insects. If you see periodical cicada nymphs, shed skins, adults on vegetation or on trees, please report your sightings to: http://magicicada.org/magicicada/mapping-updates/
We thank entomophile Gaye Williams and picture taker Nancy Perkins for providing the inspiration for this episode. Two wonderful articles, “Evolution of 13- and 17-year periodical cicadas (Homoptera: Cicadidae: Magicicada)” by C. Simon, and “The ecology, behavior, and evolution of periodical cicadas” by K. S. Williams and C. Simon, and information at Cicada Mania were used to prepare this episode.
On a recent visit to one of my favorite gardens, while enjoying the fragrances and beauty of roses, I noticed some unnerving injury, skeletonization and defoliation, on the leaves of several plants. Skeletonization is a type of injury that results when small insects use their jaws to remove soft tissues between the vascular bundles that crisscross leaves. A wide variety of beetles and caterpillars are the usual suspects when skeletonization is afoot. However, in this bed of roses, sawflies were the culprits.
Roseslug sawfly larvae feeding - YouTube
Dappled in sunshine, a pair of roseslug sawfly larvae strip nutritious tissue from the leaf blade leaving only veins and a thin layer of epidermis behind. As leaves desiccate later in summer, they crinkle and turn brown as if toasted with a blowtorch.
It’s easy to see how the curled rose sawfly got its name.
Sawflies are unusual insects, an ancient branch of the bee and wasp clan. Unlike the larvae of bees and wasps that make their living by eating nectar and pollen or the flesh and blood of insects, the larvae of most sawflies are plant feeders. At first glance, sawfly larvae look like small caterpillars with slender bodies and distinct heads. Upon microscopic inspection, you can see that the posterior segments of the sawfly’s body bear small sucker-like appendages called prolegs. Prolegs adorn the abdominal segments of plant eating moth and butterfly larvae as well. But moth and butterfly caterpillars never bear more than five pairs of prolegs. Most sawfly larvae have six or more pairs. Another difference between these look-alikes is the presence or absence of small fishhook-like structures called crochets on the prolegs. Caterpillars have them, sawfly larvae do not. Crochets help caterpillars hold onto the smooth surface of a plant leaf. Larvae of the Roseslug sawfly were the perpetrators of the skeletonization I was seeing.
After spending the winter as immatures in the soil beneath rose plants, in spring when foliage returns the roseslug sawfly completes its development, and small wasp-like adults fly to leaves where they deposit eggs with an egg-laying appendage called an ovipositor. The ovipositor has teeth like a saw’s blade, hence the name sawfly. Eggs hatch and the larvae proceed to pillage rose leaves through May and June. Fortunately, only one generation of these scalawags occurs each year, but in some years they may be abundant enough that by the end of June they can make roses look like they have been assaulted by a flame thrower.
Not much left after the curled rose sawfly finishes a leaf.
In addition to skeletonization, several leaves had large chunks of leaf tissue missing from the edges of the blade. This defoliation was the handiwork of the curled rose sawfly, an insidious leaf-munching machine that is beautifully camouflaged. When not actively feeding along the margin of a rose leaf, it is curled on the underside of a leaf or on a bud where it blends in cryptically with plant. After several days of hide-and-go-eat, the entire leaf may be reduced to nothing but a mid-vein. When its development is complete, the larva bores into the twig where it pupates. Later the small wasp will emerge, mate, lay eggs and initiate a second seasonal generation.
By mid-summer roseslug damaged leaves turn brown and crinkled.
In May and June, I regularly inspect my roses for the telltale signs of skeletonization and defoliation. If sawflies are common enough to create problems for my roses, I simply squish the little buggers between my fingers or pluck them off and toss them in the lawn to become a feast for the ground beetles or lightning bug larvae lurking in the thatch. Several environmentally friendly insecticides listed by the Organic Materials Review Institute (OMRI) with active ingredients including insecticidal soap and spinosad work well against these sawflies. OMRI listed products are used for production of fruits and vegetables marketed as organic, and when insecticide applications are necessary I try to select from the OMRI list whenever possible. As with all insecticides, always read the label carefully and follow precautions, including those safeguarding bees and other pollinators that might be on your roses. Strong directed streams of water are also reported to dislodge sawfly larvae from plants. If you have roses, be on the lookout for these rose-eating rascals.
Two marvelous references, “Insects that feed on trees and shrubs” by W. T. Johnson and H. H. Lyon, and “Managing insects and mites on woody plants: An IPM approach” by J.A. Davidson and M. J. Raupp were consulted to prepare this episode.
Last week I had the pleasure of training Master Naturalists at Benjamin Banneker Historical Site in Catonsville, MD. This little gem of a park commemorates the self-taught African American who was an astronomer, surveyor of the federal District of Columbia, author of almanacs, and naturalist. A carful observer of plants and animals, his journal describes and predicts the occurrences of one of the Bug Guy’s favorite insects, Brood X cicadas, previously featured in several episodes of Bug of the Week. While guiding Master Naturalists at the Banneker Historic Site, we were amazed and delighted by swarms of amorous boxelder bugs intent on fulfilling their biological imperative of finding mates and reproducing.
Maple samaras will soon twirl to the ground and become food for developing boxelder bugs throughout the summer.
Like the brown marmorated stink bugs we visited last week, boxelder bugs have exited buildings and outdoor refuges where they survived the ravages of winter. Having depleted winter fat reserves, they now seek seeds and other sources of food to fatten up in preparation of finding mates, mating, and depositing eggs. Banneker seems to be exquisitely suited for boxelder bugs as the park is populated by many very large, old, silver maple trees, boxelder trees, and ash trees festooned with thousands of winged samaras, those little helicopter-like seeds that spin to the ground on a breeze.
boxelder bug feeding beak (proboscis) - YouTube
Ever wonder what the boxelder bug’s beak looked like?
Female boxelder bugs deposit eggs on many surfaces. Tiny nymphs will hatch and move to the ground to consume seeds and other plant tissues.
Once the mating game is completed, females produce hundreds of eggs which will be deposited on tree bark, fence rails, tool sheds, or directly on the ground. Later this spring eggs will hatch and tiny wingless nymphs will feed on plants during summer. Nymphs of boxelder bugs have black legs and short wing pads. Their exposed abdomen is red. As nymphs mature, their black wing pads grow longer and finally cover the abdomen as they molt to adulthood. Depending on geographic location, boxelder bugs complete one to three generations each year.
Boxelder bugs mating & laying eggs - YouTube
When mating, boxelder bugs remind one of Dr. Dolittle’s pushmi-pullyu with the female doing the pulling and the male scrambling along behind. Watch as she takes a break to lay a few eggs on the side of a shed.
Wing buds on the sides of boxelder bug nymphs elongate with each molt.
During late spring and early summer, the bugs move to boxelder, which is actually a member of the maple clan, and other seed-bearing trees. In autumn, swarms of bugs become a nuisance on sunny porches, siding, and around windows and doors as they seek overwintering shelter. They find their way into homes through cracks in the foundation, gaps in siding around windows and vents, and beneath doors if sweeps are in poor repair or missing. On cold winter days they are inactive, but when temperatures warm, as they have in recent weeks, restless boxelder bugs move about and make their presence known inside and out. Boxelder bugs are not harmful to humans or pets. They do not bite, sting, or reproduce indoors. However, if you squash them on your drapes or wall, they will stain.
Boxelder bug horde - YouTube
Thousands of boxelder bugs enjoy a day in the sum on the side of a heavily infested home.
Coprophagy, the consumption of poop, is practiced by many insects including, apparently, boxelder bugs. This is likely a way to obtain minerals or other nutrients found in a bird dropping.
To limit the number of boxelder bugs taking up residence in your residence, eliminate overwintering places such as piles of lumber, rocks, and branches close to the house. Weatherproofing your home can also help bug-proof it. Caulk and seal vents and openings where electrical and plumbing utilities enter and exit the house. Repair or replace door sweeps and seal any openings around windows, doors, and foundation. With the return of temperatures in the 70s and 80s, bugs know spring has arrived and it is time to get busy. Beneath an ash or maple tree, take a moment to catch a glimpse of these curious bugs dressed in red and black.
We thank Karen and Winnie for sharing Banneker’s boxelder bugs, the inspiration for this episode of Bug of the Week. The wonderful reference “Urban Insects and Arachnids: A Handbook of Urban Entomology” by William Robinson was used as a reference.
A tardy arrival of spring witnessed the arrival of lone star ticks and mason bees in recent episodes of Bug of the Week. With temperatures suddenly in the 90’s, stink bugs are on the move in homes and offices, accumulating on windowsills, walls, and doors and buzzing about indoor lights at night. Why all the activity at this time of year? The answer lies in the age-old pattern of life crafted by the stink bug to survive the ravages of winter and emerge just in time to take advantage of bountiful leaves and fruit found on plants each spring. Millions of folks throughout the nation were treated to invasions of stink bugs last autumn as the horde sought refuge in homes, schools, and office buildings. Many people mistakenly believe that stink bugs enter buildings in winter to ‘get warm’, but this is not the case. In the natural realm where stink bugs evolved over millions of years, stink bugs sought winter refuge in sheltered spots beneath the bark of trees or in rocky crags. Protected from the onslaught of winter, stink bugs chilled out and entered a season of inactivity akin to hibernation where they awaited the return of favorable temperatures and springtime food. Lengthening days and warming temperatures signaled the return of leaves, flowers, and fruit. With the return of food sources, stink bugs answered Mother Nature’s wake-up call and moved from their refuges to the greening landscape. During the past week with record warm weather, flowers, leaves, and yes, pollen, exploded on trees, shrubs, and herbaceous plants in the Washington metropolitan region. Inside attics or beneath the siding on homes, these warm days have convinced stink bugs that spring has arrived and that it is time to return to the wild to seek food and pursue the biological imperative of finding mates and laying eggs. On warmish days this winter, every now and then I collected a stink bug or two wandering about the kitchen or living room. But as of this week, these occasional sightings have turned into a steady stream and I collect stinkers daily.
Brown marmorated stink bug 2018 - YouTube
Temperatures in the 90’s have stink bugs watching me on the bathroom door jam and wondering when we are going to the coffee shop to get a little java.
As you deal with stink bugs this spring, here are some things to consider. Recently, I was asked if “stink bugs breed in my home?” To the best of our knowledge, the answer to this question is no. In the normal course of events, stink bugs move from winter refuges to plants outdoors where they feed for several weeks before they become competent to lay eggs. In your attic or an unused bedroom there is simply no food to provide the sustenance needed by stink bugs to produce eggs. Even if a stink bug laid eggs indoors on a windowsill or wall, there would be nothing to sustain the young bugs, which require plant food for growth and development. Having made this claim, I might back-peddle just a little, as we have received reports of stink bugs feeding on house plants such as orchids and potted ponytail palms. Will stink bugs lay eggs on houseplants indoors? One homeowner discovered a batch of stink bug eggs on a houseplant late in the spring. So the final answer to this jeopardy question is yes. The chances of stink bugs sustaining a population in your home probably lies somewhere between zero and nil, unless you have bountiful fruit bearing plants in your home and do everything to ignore stink bugs dashing about on your plants.
Another question that always comes up is “what should I do about stink bugs that appear in my home this spring?” Sweeping, vacuuming, or simply picking them up and disposing of them is still our recommendation for control indoors. Because they will be active for a relatively long period of time, we are not recommending the application of insecticides to indoor living spaces to control stink bugs as they appear. Exposure of children and pets to pesticides could be worse than exposure of children and pets to stink bugs. In fact, many pets and some children will be amused by a few stink bugs wandering about.
Will stink bugs be as problematic this year as they were in the watershed years of 2010 and 2012? Probably not. Although stink bugs have now spread to 44 states and 4 Canadian provinces, in our region most people agree that fewer stink bugs plagued gardens, homes, and farms recently than they did several years ago. Fascinating studies suggest that a combination of climatic events and Mother Nature’s Hit Squad of predators, parasites, and pathogens have conspired to smack down populations of stink bugs. Scientists at Virginia Tech found that rapidly plunging temperatures associated with weather phenomena such as the polar vortex may reduce survival of overwintering stink bugs. Studies conducted at the University of Maryland revealed that young stink bugs thrive only when the proper complement of microbes are present in their gut. These microbes pass from mother to offspring when youngsters consume exudates smeared on the surface of their eggs by their mother. Without this complement of microbes, survival and development of stink bugs is reduced. Authors suggest that high temperatures may harm this microbiome and thereby reduce colonization by stink bugs. Maybe our record warmth does some good after all.
With respect to Mother Nature’s Hit Squad, in previous episodes of Bug of the Week, we met vicious predators such as the Chinese Mantis, Wheel Bug, and Black and Yellow Garden Spider as these feasted on stink bugs. Scientists at the USDA found several species of indigenous predators such as ground beetles and katydids attacking eggs of stink bugs in orchards and vegetable crops. Researchers at the University of Maryland discovered several species of tiny native wasps metering out significant mortality on eggs of stink bugs in ornamental plant nurseries. And yes, stink bugs are susceptible to pathogens as well. Scientists at Cornell have described a tiny microsporidian parasite called Nosema maddoxi infecting several populations of stink bugs around the nation. Collectively, weather events and natural enemies are helping to win the war on one of the most serious recent invaders to arrive in our country.
To learn what to do when stink bugs get inside, and how to keep them out, watch the following video:
Brown Marmorated Stink Bug Control: Keeping Stink Bugs Out of Your House - YouTube
The following articles were used to prepare this episode:
“Cold Tolerance of Halyomorpha halys (Hemiptera:Pentatomidae) Across Geographic and Temporal Scales” by Theresa M. Cira, Robert C. Venette, John Aigner, Thomas Kuhar, Donald E. Mullins, Sandra E. Gabbert, and W. D. Hutchison.
“The Importance of Gut Symbionts in the Development of the Brown Marmorated Stink Bug, Halyomorpha halys (Sta˚l)” by Christopher M. Taylor, Peter L. Coffey, Bridget D. DeLay, and Galen P. Dively.
“Frequency, efficiency, and physical characteristics of predation by generalist predators of brown marmorated stink bug (Hemiptera: Pentatomidae) eggs” by William R. Morrison III, Clarissa R. Mathews, and Tracy C. Leskey.
“Field surveys of egg mortality and indigenous egg parasitoidsof the brown marmorated stink bug, Halyomorpha halys, in ornamental nurseries in the mid-Atlantic region of the USA by Ashley L. Jones, David E. Jennings, Cerruti R. R. Hooks, and Paula M. Shrewsbury.
“Nosema maddoxi sp. nov. (Microsporidia, Nosematidae), a Widespread Pathogen of the Green Stink Bug Chinavia hilaris (Say) and the Brown Marmorated Stink Bug Halyomorpha halys (Stål)” by Ann E. Hajek, Leellen F. Solter, Joseph V. Maddox, Wei‐Fone Huang, Alden S. Estep, Grzegorz Krawczyk, Donald C. Weber, Kim A. Hoelmer, Neil D. Sanscrainte, and James J. Becnel.