Bug o’the Week – Green-striped Darner

Salutations, BugFans,

 

The BugLady had some good luck stalking dragonflies in the summer of 2014, even the elusive Common Green Darner sat still for her (finally).  She was also able to tiptoe up on some mosaic darners, and now she’s waiting for her identification skills to catch up.  Darners are a group of large dragonflies 2 ¾ to 3+ inches long) in the family Aeshnidae, within which the mosaic darners, aka “blue darners,” are in the genus Aeshna.  Why “mosaic?”  Because their abdomens are decorated with a mosaic of blue/green/gray spots (a mosaic is “a picture or pattern produced by arranging together small colored pieces of hard material, such as stone, tile, or glass:”).  Lots of birders get interested in dragonflies – they’re another good reason to be out in the field – and the BugLady figures that mosaic darners might appeal to the kind of birder who loves identifying sparrows or shorebirds.  Or gulls.

 

There are 20 or so Aeshna darners in North America, and identification can depend on colors and patterns that vary within a species, and on a good look at what Monty Python called the dragonfly’s “naughty-bits.”

 

Let’s demystify those naughty-bits a little.  The final (10th) segment of the abdomen of both male and female dragonflies bears a pair of structures called cerci (singular – cercus).  The male has an additional structure called the epiproct below/between the cerci; the female has an ovipositor or egg-laying pore, but it’s located on the underside of the eighth segment.  The female’s cerci, whose function(s) is/are not well understood, may be small or may, especially in the darners, look similar to a male’s.  The male uses his cerci to clasp the female at the back of her head and his epiproct to grasp the top of her head, sometimes injuring her eyes in the process (the joined male and female are “in tandem”), then the female bends the tip of her abdomen up to his abdomen, near the base of the thorax, where he has placed some of his bodily fluids (they are now in a “mating wheel”).  The BugLady wouldn’t have to be coy about this, but internet filters of certain BugFans who get BOTW at work have been known to reject episodes that use the Queen’s plain English.  In some species, the cerci seem more “brittle” and are known for breaking off.  Anyway, the cerci and epiprocts are shaped slightly differently in the various species of mosaic darners.

 

And so is the first stripe on the side of the thorax (lateral thoracic stripe) (not the one on the top of the thorax, directly behind the eyes).  Is it straight or notched?  Deeply, acutely notched or shallowly?  Is the stripe all the same color or does it blend from blue to green?  And what about those color patterns?   Females of some species, like the Lance-tipped darner (so-named because the male has a spine on the end of each cercus) may have yellow, blue, or green stripes on a brown thorax, while the background color of the thorax of others, like the Canada darner, may be almost black or light caramel brown (both species were mentioned in a previous BOTW episode about mosaics http://www4.uwm.edu/fieldstation/naturalhistory/bugoftheweek/not-green-darners.cfm.).  A not-universally-embraced method of identifying a few mosaic species depends on the shape of the pale markings on the top of the second abdominal segment.  And, oh yes – darners tend to have darker coloration on cooler days than on warmer ones.

 

The Green-striped Darner (Aeshna verticalis) is a Northeastern darner, found from Minnesota/northern Iowa/southern Canada to Nova Scotia to New Jersey; it is rarely found south of Ohio.  Its life story is similar to that of other mosaics.  Green-striped Darners may feed until dusk on small, flying insects that they are able to eat while on the wing; like other dragonflies, it can be found in feeding swarms far from water.  Kurt Mead, in Dragonflies of the North Woods, says that they have the “reputation of repeatedly hovering over the same area.”  In Dragonflies of Wisconsin, Legler notes that they “may be found resting on tree trunks or hanging from branches,” which is exactly where the BugLady found them, toward the end of the day.

 

The breeding habitat is marshy, sedgy wetlands, including ponds and sometimes slow streams.  Males patrol along the vegetation at the wetland’s edge, chasing other males away.  Females lay eggs in the stems of aquatic vegetation, just above the water line, using their impressive-looking spiny ovipositors to make slits (thanks to BugFan Freda for the shot of the mosaic ovipositor).  Young mosaic darners (naiads) prey on their aquatic neighbors from perches on aquatic plants and will even eat a tiny fish if they can catch one.  They overwinter under water and emerge in early summer of the next year.

 

Sources agree that its bright colors and an all-green thoracic stripe that is notched shallowly/obtusely are diagnostic for this green-faced dragonfly (the second, or posterior, lateral thoracic stripe blends from green to blue).  A North Carolina site claims that this dragonfly can be “called” in flight at 100 feet using binoculars, but the BugLady’s not there yet.  Sources add that it is similar to the “duller” Canada and Lance-tipped darners and that all three species have similar, paddle-shaped cerci.

 

Besides Mead’s and Legler’s books, the BugLady recommends the Beginner’s Guide to Dragonflies by Nikula, Sones, Stokes and Stokes for your thorny dragonfly ID problems.  On-line, try the Wisconsin Odonata Survey at http://wiatri.net/inventory/odonata/, the Wisconsin Dragonfly Society http://wiatri.net/inventory/odonata/WDS/, and, for an overview, Odes for Beginners, with its spiffy, dragonfly-shaped cursor (though the site can be hard to navigate) http://www.odesforbeginners.com/genus/darners/aeshna.aspx).  Thanks to BugFan Ryan for identifying one of the Green-striped dragonflies; as always, any misidentifications belong to the BugLady.

 

The BugLady

Bug o’the Week – Ostracods

Salutations, BugFans,

 

By now it’s no secret that the BugLady is enthralled by wee critters that swim about in the water, especially the water of ephemeral ponds.  Who needs charismatic megafauna!  (Reminder – the BOTW definition of “bug” borrows more from that of a first grader than that of an entomologist).

 

Once upon a time, there were ostracods.  How do we know that?  Because these tiny, aquatic critters, critters that you would never expect to contribute significantly to the fossil record, in fact managed to produce the most numerous fossils of all arthropods http://www.nhm.ac.uk/research-curation/earth-sciences/micropalaeontology/microfossils/ostracods/index.html.  Of all arthropods – that’s insects, spiders, centipedes, millipedes, and crustaceans.  Since the Ordovician period, 485 to 443 million years ago.  They’ve even been found in amber (fossilized tree sap), where they may have landed during a flood.  So pervasive are they that a system has been developed for evaluating ancient climates (paleotemperatures) called the mutual ostracod temperature range (MOTR), based on a measurement of the building blocks in the ostracod’s “shell.”  And, since the shapes of ostracod shells are indicators of their ecological milieu and of their feeding habits, they are used as paleoenvironmental indicators http://smithsonianscience.org/2014/06/climate-change-will-impact-even-deep-ocean-ecosystems-scientists-say/.  And, fossilized ostracods are used to date marine sediments.

 

In the etymology department, Wikipedia tells us that the Greek root “ostracon” means “shell” or “tile,” and that “the word ‘ostracize’ comes from the same root, due to the practice of voting with shells or potsherds.”

 

Ostracods’ most recent family tree seems to read: Phylum Arthropoda (“jointed appendages”) (yes – they have appendages), subphylum (formerly class) Crustacea, and class (formerly subclass) Ostracoda.  The Monterey Bay Aquarium website explains that because they look like a shrimp inside a seed pod, they are commonly called seed shrimp (and an older European nickname is mussel shrimp), but the BugLady thinks they look like pistachios.  Fellow Crustaceans include the familiar pill bugs, crabs, crayfish, shrimp, and lobsters, as well as barnacles, fairy shrimp, and minute aquatic forms like daphnia, and copepods.

 

Ostracods are found worldwide, and there are lots of ostracod species, both marine and non-marine, with many more waiting to be discovered.  The BugLady found estimates of 8,000 to 13,000 total living species, 2,000 of which are non-marine (non-salt water), with 420 of those non-marine species being found in North America.  As many as 50,000 additional species have been identified from fossils.  About half of the non-marine species are in the family Cyprididae, and the BugLady suspects that the ostracods she photographed in the ephemeral pond belong in that family because the family is noted for their ability to swim, and for tolerating stagnant, oxygen-poor waters and having drought-resistant eggs, larvae and adults – important adaptations for an ephemeral pond dweller.

 

If you can think of an aquatic habitat – running water, still, permanent, ephemeral, underground, surface, salt, fresh, hot sulfur, brackish, shallow, or ocean abyss – there are ostracods living in it.  They also occupy mud and sand, algal mats, clumps of wet moss, and damp tropical soils.  One species hangs onto the underside of the surface film in open water.  Freshwater species probably evolved from ostracods living in brackish waters that flooded frequently, so that they gradually adjusted to lower saline levels.  One source speculated that the biggest jump in new species of ostracods may come when groundwater is analyzed for their presence.

 

Many species are generalists, not limited to a single habitat, and while most freshwater species are “benthic” (creeping about on the substrate/debris at the bottom of the body of water), some are active swimmers and others are found on aquatic plants (but very few are planktonic).  In general, ostracods prefer the shallow water at the wetland’s edge, up to a depth of about three feet, and they are more active in light than in shadows.  They can tolerate a wide range of water chemistry and temperature, but they aren’t found in highly polluted waters.

 

Ann Haven Morgan, in her “Field Book of Ponds and Streams,” calls ostracods “another army of minute crustaceans averaging only a millimeter in length, and impossible to tell apart with a simple lens.”  What they have in common is two limy/calcified “shells” called valves that are hinged at the back and held together with muscles like a scallop’s.  This makes them look like teeny clams – teeny, hairy clams, because the outside of the valves may be covered with hair-like setae.  The body inside the “shell,” is somewhat flattened and is not segmented.  The head end has two pairs of antenna-like appendages plus two pairs of mouthparts (mandibles and maxillae).  Depending on the species, those all-purpose antennae, especially the second pair, may be used for digging, climbing, locomotion, and feeding, and males use them to clasp females.  The thorax area has three pairs of legs that are variously used for locomotion, respiration and grooming.  The rear end has two long “tails” called caudal or furcal rami that can also be used for locomotion http://www.bgs.ac.uk/discoveringGeology/time/Fossilfocus/ostracod.html.  The appendages can be tucked inside the valves and the valves pulled shut if the creature is alarmed.

 

Ostracods come in a variety of colors from dark gray to yellow to red to blotched, and species living on green plants are often gray, green or brown.  Most freshwater forms measure between 1mm and 3mm, but a South American freshwater species is about a half-inch long, and some marine species are giants at almost 1 ¼” (“as big as a meatball,” says one source).

 

Scientists tell us that when they collect ostracods, most of the individuals they find are female.  The number of males in a population depends on an ostracod’s species, and the type of reproduction is determined by the number of males in the population.  Reproduction by parthenogenesis (virgin birth) is common, especially in freshwater ostracods (in some species, males have never been found), but in species with more males, sexual reproduction is de rigueur.  Eggs are laid on rocks and vegetation or simply loosed into the water; they hatch into active Nauplius larvae that have appendages on their head for swimming and that shed eight times on their way to adulthood.  Eggs that are left in the mud when an ephemeral pond dries up will hatch when water returns, no matter how long it takes.

 

A diverse crowd like the ostracods shows up on many rungs of the trophic ladder.  There are carnivores/predators, herbivores, detritivores, and scavengers but ostracods are generally characterized as omnivorous scavengers.  They eat tiny organisms like algae, diatoms, bacteria, molds, and pieces of organic detritus that are present in the water or on vegetation.  In some, food is delivered to the mouthparts by a current set up by the appendages.  The BugLady found a picture of an ostracod straddling an aquatic leaf, rasping off food on both sides as it moved along the edge of the leaf.  Ostracods are eaten by hydra and other benthic organisms and by small fish, larval salamanders, and waterfowl; one species has been shown to be able to survive a trip through a bluegill’s digestive tract.

 

Whether swimming or creeping, ostracods locomote by extending their appendages from between the valves, with the valves “ajar” https://www.youtube.com/watch?v=F32fyIeVBAM.  Their main sense is touch, they move their antennae constantly and also have sensory hairs on their bodies.  The Nauplius larva has a simple eye, as do the adults of some species.

 

The Ward Science supply company will sell you some ostracods, but they urge consumer responsibility: “Never purchase living specimens without having a disposition strategy in place,” they say, later adding that “In order to protect our environment, do not release any of these organisms into the wild. When you are done with the crustaceans, add bleach to the culture and dump it down the drain.”  Good on you, Ward Science Supply.

 

Oh yes – several species of marine ostracods are bioluminescent (using luciferin and luciferase, the same two chemicals that lightning beetles use), and they glow blue at night in the water and on the sand https://oceanwire.wordpress.com/tag/ostracod-crustaceans/.  The light is in a secretion that the ostracod releases when it is disturbed.  The Japanese call them sea fireflies (umi-hotaru), and the BugLady came across an anecdote about Japanese sailors during WWII reading their instruments and charts by the light of bowls of luminescent ostracods.

 

Little bug – big story.

 

The BugLady

Redefining Nature Centers

Riveredge is more than a nature center. Its legacy of innovation, partnerships, and leadership in the areas of land restoration, research, and inquiry-based education throughout Wisconsin serve as strong foundation to its future initiatives.  Today, Riveredge is pioneering methods of redefining a community’s relationship to a nature center. Riveredge is achieving its mission by empowering and supporting communities to live in harmony with their natural environment…oh, and having fun it in too.

One way we are currently re-writing assumptions of nature centers is through school partnerships. Formal partnerships between local nature centers and school districts are an opportunity to deepen learning and life skill outcomes.  Partnerships that expand beyond field trips allow for deeper relationships between a local nature and their communities.  Riveredge Nature Center (RNC) and the Cedarburg School District (CSD) have completed two years of such a partnership.  We are sharing the information about our partnership as a way to spread the word and help other nature centers and environmental organizations consider perusing deeper relationships with their school districts which may positively affect not only the students, but the entire community.  If you’d like to learn more please consider the following items.  Thank you to the Wisconsin Environmental Education Board for funding our evaluation project of this partnership through a 2013-14 grant.

Our partnership with Cedarburg School District has led us to think even BIGGER at Riveredge.  How could we reduce barriers to outdoor and environmental learning within our formal education systems?Jewel & Megan

In five years’ time, we see the students of your school district healthier, happier, more creative, and inspired by the world around them. We envision a school system where the outdoors is interconnected to the foundation of every day just as technology is interwoven through all subject areas.  We witness schools that do not have to make the choice between less recess time and more reading time because teachers have learned ways of transforming their local outdoor spaces into classrooms. We see the evolution of the next generation of scientists.

The vision of this cutting-edge project is to work in a true partnership with local school districts to transform the culture of our formal education system through the integration of outdoor learning experiences, environmental science learning, and the implementation of sustainability projects and initiatives.

In its most basic description, the “Riveredge School Naturalist Program” will place a fully funded environmental educator into local schools or school districts four days per week for five years, to meet the needs defined by the school district in order to achieve this vision.

Interested in learning more?  Contact Jessica Jens, Executive Director (jjens@riveredge.us or 262-416-1068)

 

Bug o’the Week – The Swallowtail That Got Away

Greetings, BugFans,

 

Roger Tory Peterson once said that the secret of being a good birder is looking twice.  The same can be said of other natural history pursuits, especially dragonfly and butterfly-watching because butterflies and dragonflies, like birds, were issued wings, but not maps, and some routinely show up far away from their natural ranges (to the delight of all).

 

One fine June day in 2007 (early in her digital point-and-shoot days), the BugLady spied this beautiful swallowtail (family Papilionidae) in the middle of a field and was able to get a single shot of it before it left (“Hmm,” she thought, “What was that?”).  Not a Black swallowtail – Black swallowtails, to the BugLady’s eye, have a different “attitude” – they seem very “trim” and their movements are “tighter” than the loosey-goosey Tigers.  Turns out that it was a Pipevine Swallowtail (Battus philenor), a species that was not on her radar.

Black swallowtail

Black swallowtail

Pipevine swallowtail

Pipevine swallowtail

Wisconsin has two common species of dark swallowtails – the Black swallowtail and the dark morph female Eastern tiger swallowtail – and we host two dark species that are uncommon strays, the Pipevine and the Spicebush swallowtail.  The latter two are drifters whose caterpillar food plants are not native to Wisconsin.  The classy PS has a wingspan between three-and-a-half and almost five inches, varying intensities of blue on the upper surface of the wings (males are brighter) and flashy red, white and blue spots on the lower surface of the hind wing.  http://bugguide.net/node/view/651405/bgimage http://bugguide.net/node/view/444008/bgimage http://bugguide.net/node/view/389217/bgimage (about those symbols for male and female – the circle with the plus sign at the bottom, the “hand mirror,” stands for female) (someone put that mnemonic into the BugLady’s head in high school, and now she passes it on).

 

Tiger swallowtail

Tiger swallowtail

The natural habitats for this lovely wanderer include fields, parks, gardens, dappled woods, and edges from Central America through the southern US, wherever its food plants grow; and its travels take it as far north as Oregon, southern Canada, and New England.  PS caterpillars are specialists, feeding on Pipevine/Dutchman’s pipe and Virginia Snakeroot, plants in the genus Aristolochia in the Birthwort family Aristolochiaceae.  Only one member of the Birthwort family, wild ginger (Asarum canadense), grows in Wisconsin, but captive PS caterpillars reportedly will starve to death before they will eat it.  Adults nectar on a variety of flowers (and, like bees, can learn the benefits of “flower constancy” – that is, they can connect specific kinds of nectar with certain colors of flowers).  And then there’s “puddling.”

 

Male butterflies of many groups, not just swallowtails, also get nutrients from “puddling” – using their proboscis to soak up moisture, proteins, amino acids, and minerals from damp mud, sand, carrion and feces.  Concentrations of the desired compounds may be dilute, forcing the butterfly to consume lots of liquid and then concentrate the salts.  Why?  First, active insects need sodium for neuromuscular activity.  He is more active than she is, and the “salt-free” diets of both caterpillars and adults don’t supply much of that nutrient.  Second, some species of butterfly must imbibe a specific amount of minerals before they can produce the pheromones that will attract a mate (the female may rate her suitor by the quality of his pheromones).  And third, he incorporates sodium into the spermatophore (sperm packet) that he passes to the female.  She, in turn, distributes most of the sodium into her eggs, which increases her egg production and gives her offspring a salty survival “boost” (for an article about this check out the website of the Texas Master Naturalists Cross Timbers Chapter http://www.ctmn.org/archives/200309_2C.html).

 

The BugLady was pleased to be reacquainted with the excellent “Butterflies of Massachusetts” website (http://www.butterfliesofmassachusetts.net), which offers thoughtful analyses of 200-plus years of butterfly data and tells us that the PS was first reported in that state in 1840 and was not uncommon there for the next century, as people planted Dutchman’s pipe on their porches, trellises and arbors.  When that practice faded in the mid-20th century, PS reports dwindled.  PS’s overwinter in the chrysalis stage, and the chrysalis is considered to be cold-intolerant, but historically there seem to have been permanent PS colonies in parts of Massachusetts – and Wisconsin – where Dutchman’s pipe was planted.  Butterflies of Massachusetts posits that our warming climate may allow the host plants to move north, followed by their butterflies.

 

Dutchman’s pipe and Virginia snakeroot are poisonous, and the chemicals that render the aposematically (warningly)-colored caterpillars distasteful and toxic are ingested and processed by them, stored, and passed on to the body of the adult.  So, if you’re a Spicebush, a Black, or a black-morph Tiger Swallowtail (or even a non-swallowtail Red-spotted purple), looking like a PS is a good thing (less so here in God’s Country, where the PS is so uncommon that predators haven’t had a chance to learn their lesson).  Cashing in on another species’ defense strategy via imitation is called Batesian mimicry.  If black swallowtails and spicebush swallowtails also taste bad, and research suggests that they do, we can add Mullerian mimicry to the story (species with varying noxiousness imitate each other, resulting in a larger pool of “teachers” for their predators).  In Butterflies of the Great Lakes Region, Douglas and Douglas state that “the pipevine swallowtail is a ‘tough’ butterfly, with resilient, hard-to-crush cuticle that probably makes the butterfly more resilient if it is accidentally attacked by birds unaccustomed to its distasteful properties.” The similarities of the four species are illustrated here: http://louisiananaturalist.blogspot.com/2009/06/four-dark-swallowtails.html.

 

Red-spotted purple

Red-spotted purple

According to Mike Reese’s Wisconsin Butterflies website (https://wisconsinbutterflies.org/), “In the Summer 2001 issue of American Butterflies, an article called “The Pipe-dream Project” suggests that planting pipevines could help in increasing the distribution and abundance of this species, in a similar manner in which Bluebird houses have aided that species. Since the host plants do not grow here naturally, plantings of acceptable cultivated varieties (the underlining is the BugLady’s) of pipevines might be useful.”  A butterfly gardening website warns against planting tropical Aristolochias like Giant Dutchman’s pipe (A. gigantea), which the PS will oviposit on, but which is so toxic that it kills the caterpillars.

 

Males patrol for females; females lay clusters of beautiful red eggs on young, tender Aristolochia vegetation (http://bugguide.net/node/view/134202/bgimage) (the bigger the plant, the more eggs she lays), and the larvae feed gregariously for their first few instars http://bugguide.net/node/view/182969/bgimage, before becoming loners as they get older. The awesome red or black caterpillars are decorated with fleshy bumps and filaments http://bugguide.net/node/view/114704/bgimage (one source said that warmer caterpillars are redder caterpillars http://bugguide.net/node/view/146519/bgimage).

 

Like other swallowtails, the caterpillars possess an osmeterium, a retractable, fleshy, forked horn that appears when they are alarmed http://bugguide.net/node/view/765568/bgimage, looks like a snake’s tongue, and emits a foul odor.  PSs overwinter in the chrysalis stage (http://bugguide.net/node/view/4949/bgimage); there are two broods in the north and three or more at the southern edge of its range.

 

PSs have developed an interesting behavior, gathering in groups on the outer edges of treetops in late afternoon, perching overnight, and dispersing well after sunrise (there are anecdotal reports of feeding aggregations, too).  Research by Pegram, Han and Rutowski in Arizona showed that as many as two dozen PSs will gather in one spot and deliberately orient their wings in a plane/posture that makes the aposematic red and the iridescent blue even more conspicuous http://bugguide.net/node/view/389956/bgimage.  The timing of this “in your face” display (the BugLady’s term, not the researchers’) coincides with the times of day when insectivorous birds are most active; the tree-top location gives them maximum exposure to the last and first rays of the sun (the iridescence can even be seen for a while after sunset); and their location keeps them out of the reach of ground-predators that may hunt by smell, not sight.  In the experience of the researchers, the only butterflies taken by predators were those that had perched individually, away from the group.  It pays to advertise.

 

Look twice,

 

Kate Redmond, The BugLady

Bug o’ the Week – A Bevy of Tachinid Flies

Howdy, BugFans,

 

It’s Science Vocabulary Day.

 

A common prairie resident in late summer is a large, noisy, skittish Tachinid fly with a bristly, bulbous, shiny black abdomen; the BugLady wrote about them in BOTW’s infancy in 2008.  Tachinidae is considered the second largest fly family (after the crane flies!), and it’s suspected that once all the undiscovered species of Tachinids have been described and welcomed into the fold, it may become the largest fly family.  The term “house-fly-like” is used to describe the family, and many family members can be confused with house flies (family Muscidae), blow flies (Caliphoridae) and flesh flies (Sarcophidae).  But, in a family made up of more than 12,000 members (around 1300 species in North America) there is considerable variation.  Tachinids are found worldwide, but they’re most populous in the tropics.  Taxonomically speaking, it’s a fairly young group (they’ve only been around since the middle Eocene – about 45 million years ago).

 

By definition, Diptera (flies) have only two wings.  The hind pair has been modified into two knob-shaped organs called halteres that help the fly balance.  The front wings of tachinids and several related groups have disc-like projections of the fore wings called calypters (from the Greek “kalypter” for covering or sheath) that cover the halteres.  Other features that make a tachinid a tachinid are a bristly body (usually) and short, flat, three-segmented antennae with a modified bristle (called the arista) on the third segment that help it monitor moisture and temperature in its environment.  Some are brightly-colored but many are drab, and many have very large eyes.

 

Calypters

Calypters

Tachinids attract our attention because of what they eat.  The larvae of all species that have been studied are parasitoids (with a few parasites thrown in).  Remember, a parasite doesn’t kill its host (because what would it do then?) but a parasitoid does.  Parasitoids feed on the non-essential organs of its host first, and then the vital organs, timing the death of the host to correspond with the end of its larval stage.  Parasitoids may attack their hosts at any stage of the host’s life, but only larvae can be parasitoids.

 

It’s the organisms they choose for their hosts that make tachinids interesting to us (OK – the mechanisms are pretty amazing, too).  Hosts are chosen from throughout the Arthropoda (they’re mostly plant-eating insects with a few spiders and centipedes thrown in) and they include many (large, soft, slow-moving, conspicuous) caterpillars.  There are lots of agricultural pests on their menu, like sunflower moths, codling moths, cabbage loopers, and gypsy moths, plus true bugs, beetles and grasshoppers.  Their economic value as biological controls is huge, and non-native tachinids have been imported to attack non-native pests (on the other hand, some species also pick on honeybees and beneficial predaceous stink bugs and ground beetles, and sometimes, an imported tachinid “goes rogue” and impacts desirable native species like the giant silk moths).  Adults feed on nectar from flowers (they’re considered pollinators) and on honeydew from aphids that falls on the leaves; some species don’t feed as adults.  Most tachinids are endoparasitoids, feeding within their host, and most are generalists, with a range of species they prey on.

 

Within that basic game plan lay quite a variety of strategies, mainly around where the egg is laid and what stage the embryo is in when the egg is laid.  Plan A, a common (and probably ancestral) method is to lay a standard insect egg in a hard-to-reach spot on the outside of the host’s body (for example, on one of the last few segments of a caterpillar) or to inject it directly into the host’s body (this takes a little planning, probing for weak spots in a host’s exoskeleton).  The embryo develops, the larva (maggot) hatches, and it burrows into the host.  Females probably use sight and smell to guide them to the right plants and the right hosts, and possibly, auditory and tactile cues, too.

 

Plan B – Ovoviviparity.  Viviparous means that the young develop inside Mom’s body, but not in an egg.  Oviparous means that the female deposits an egg that will hatch.  Ovoviviparous means that the young tachinids develop in eggs in Mom’s body, but they hatch there before being deposited as larvae (in insects, synonyms are larviparous and ovolarviparous).  Females of many species carry a supply of ripe eggs and can hatch a larva “on demand” onto the host or onto flowers nearby, where it can stalk its own host.  In between Plans A and B are species that store the egg in the ovary so that it has only a very short incubation period after it’s deposited.

 

Plan C – Mom deposits eggs directly onto the plants.  A host may eat the egg while feeding, or the maggots may hatch out and go hunting on their own (in one group, Mom lays the eggs directly into the host’s mouth, but the BugLady doesn’t want to know any more about that). Tachinids that lay eggs on the vegetation or the ground, where connections to the host are random, lay more eggs than those that lay directly on hosts.  When more than one larva ends up in a single host; they may duke it out within the host’s body or may develop side by side.

 

Once on board, the first-instar maggot feeds on hemolymph, the insect equivalent of blood.  The serious feeding begins during the maggot’s second instar, when it feeds on its host’s tissues and fat, and when it also attaches itself to its host’s tracheal system so it can tap into its host’s oxygen.  During this stage, the host’s immune system attempts to encapsulate the invading maggot, but because of its access to oxygen, the tachinid maggot is usually able to free its head end from the capsule and keep on eating.  A host species’ susceptibility to this form of attack depends on the ability of its immune system to encapsulate a maggot successfully (one source referred to “coevolutionary arms races between parasitoid and host”).  In the third instar, the host’s vital organs are eaten, and if the food runs out early, the adult tachinid will be stunted.  Tachinid larvae seem to be unaffected by toxins its host has eaten.  The larva may pupate with the host’s body or exit and pupate elsewhere.

 

The big, hairy, jumpy tachinid flies that the BugLady wrote about back in 2008 were (probably) Archytas apicifer.  Adults can be seen on flowers, looking like mini-bumblebees, and their offspring are parasitoids of forest tent caterpillars, tiger moths, prominent moths, corn earworms, army worms, and tomato fruitworms.  Several Monarch butterfly sites list Archytas sp. as monarch predators.

 

Archytas apicifer

Archytas apicifer

The next tachinid that the BugLady found was the excellent Feather-legged Fly (Trichopoda sp), a completely different-looking critter (but with the same proclivities).  They specialize in stink bugs, squash bugs, and leaf-footed bugs, and it is hoped that they’ll develop an appetite for the newly arrived (in Wisconsin) brown marmorated stink bug.

fthr-lggd fly11 1

Feather legged fly

 

Since then, she has photographed a number of different-looking flies that, to her surprise, turned out to be tachinids, too.  Meet Gymnosoma sp. (you generally can’t identify these guys to species with a photo).  “Gymnosoma” means “naked body” and these house fly sized tachinids have few abdominal bristles.  They lay their eggs on adult and nymphal stink/shield bugs.  Adults drink nectar.

 

Gymnosoma

Gymnosoma

And Cylindromyia sp, a generalist feeder whose larvae develop in a variety of stink bugs that feed on fruit crops, moths, and on short-horned grasshoppers.  Cylindromyia mimics wasps in color, shape and posture (but wasps have four wings).  Its larvae also feed on some of the beneficial predatory stinkbugs, so it gets mixed reviews.

 

Cylindromyia

Cylindromyia

The BugLady thinks this is Belvosia sp, a predator of a number of moth caterpillars in the sphinx moth and silk moth families.  Buck moth caterpillars, species of species concern in Wisconsin, are among its target species.

 

Belvosia

Belvosia

Kate Redmond, The BugLady 

Bug of the Week archives:
http://www4.uwm.edu/fieldstation/naturalhistory/bugoftheweek/

Bug o’ the Week – Cornworms and Hornworms and Sqush borers, Oh My!

Howdy, BugFans,

 

Instar – the feeding stage between molts in an immature insect.

 

The New Year has arrived and with it, seed catalogs.  Gardeners, like women in childbirth, think mistily of the fruits rather than the labor.  Here are three moths that applaud our gardening efforts (alas, the chief contenders for the BugLady’s patio tomatoes are chipmunks, not bugs).  Those who don’t want to share can find a lot of information about pest control on-line and at your local Agricultural Extension office.

 

If you don’t look sharp, a bite of late-season sweet corn can be a “two-fer” – a carb and a protein in one buttery mouthful (the BugLady respectfully refers BugFans to the recent episode about Entomophagy).  CORN EARWORMS (Helicoverpa zea) (Zea refers to the scientific name for corn and maize), in the Owlet moth family Noctuidae, are as fond of corn as we are, but some of their aliases – Tomato fruitworm, Vetchworm, Bollworm, and Sorghum headworm – show the range of plants that they feed on.  CEws eat a variety of field crops, some of which, like sorghum and lettuce, are favored, and others, like spinach, broccoli, legumes, and squashes are secondary hosts.  They may damage fruit and flower crops, too.  In the wild, they live on various species of wild geraniums and legumes, and adults nectar on flowers.  More than 100 species of insects feed on the caterpillars, including one called the Insidious Flower Bug (Orius insidiosus), a tiny bug that is known to pursue early stages of CEw caterpillars but that also painfully and almost invisibly bites humans.

 

Corn earworm

Corn earworm

The CEws’ summer range extends throughout North America almost to Alaska and northern Canada, but their larvae are not very hardy; they can’t overwinter north of a line from southern New Jersey through Kansas and so must migrate back every year.  In fact CEws are great travelers, moving short distances within crop fields and greater distances flying nocturnally, with the wind, about 40 feet above the ground.  Large groups of moths engaged in longer migration flights may fly a half-mile or more above the ground and cover 250 miles.   Humans, via shipments of corn ears, assist in the dispersal of the larvae.

 

How does a larva get onto the corn?  A female CEw sends out a pheromone signal which the male follows, but if she cannot detect corn silk in her neighborhood, she won’t develop pheromones at all.  Up to 35 eggs per day (as many as 3,000 per female) are laid on corn silk and corn leaf hairs.  Emerging caterpillars must make a hole in the egg large enough to squeeze their head through, and they line the hole with silk to help the rest of their body slide out.  Once they’ve exited, they eat the egg and then start in on the corn plant.  Caterpillars may feed communally on any part of the plant during their first few instars (which is considered the more destructive phase of their lives); older CEw larvae concentrate on the kernels, where they will kill and eat the competition – their brethren.  They pupate in the soil below the plant and can enter diapause (a state of suspended animation) to wait out unfavorable climate conditions.

 

In the “Virtues of Chaos” category, the BugLady thinks that this lovely green-eyed moth that has been languishing for four years in the X-Files folder is an adult CEw.

 

Corn earworm moth

Corn earworm moth

You get remarkably different results when you Google “FIVE-SPOTTED SPHINX MOTH” (the adult) than you do when you look up its notorious offspring, the TOMATO HORNWORM.  The Five-spotted sphinx (Manduca quinquemaculatus) (“five spotted”) is in the same moth family, Sphingidae, as the White-lined sphinx that had such a dramatic population boom here in the fall of 2013.  The gray-to-brown FSSM is spectacular, with a four-plus inch wingspan, five spots on the abdomen and what looks like a snake head on its thorax http://bugguide.net/node/view/585174/bgimage, http://bugguide.net/node/view/107467/bgimage http://bugguide.net/node/view/579428/bgimage http://bugguide.net/node/view/921545/bgimage.

 

Tomato hornworm

Tomato hornworm

THw caterpillars can be found in gardens and agricultural fields in the eastern half of North America.  The three-to-four inch larva is both dramatic and well-camouflaged, and it can be told from the closely related tobacco hornworm by the chevron-shaped markings along its sides and by a dark/black horn (the tobacco hornworm has simple white slashes and a red horn).  Both species defoliate plants in the Nightshade family, Solanaceae (tomato, tobacco, potato, eggplant, etc.) (tobacco hornworms are adapted to metabolize the toxic nicotine and use it as part of its defense arsenal, but that’s a different story), and the caterpillar is said to consume as much in its final instar as in all of its previous instars combined.  Adults visit tubular flowers like Bouncing Bet and petunias in late afternoon and early evening.

 

Females lay eggs on leaves – usually on the bottom surface.  The eggs hatch quickly and the caterpillars feed for about a month before dropping down to pupate in a burrow in the soil.  There are two generations per year up here in God’s Country and more than that to the South; the final generation of the year overwinter as pupae.

 

Planting marigolds around your tomatoes is one way to deter THws.  Far more fun is nocturnal hand-picking, aided by yellow/amber filtered goggles and a UV light.  The tomato foliage will look deep red/orange and the caterpillars bright green.

 

Isn’t this a dynamite moth!  Alas, both its common and scientific names, SQUASH-BORER MOTH (Melittia cucurbitae) (cucurbit is Latin for gourd) tells us what its larvae are up to.  The SBM (not the “smiling by myself” communication acronym) is in the Clear-wing moth family Sesiidae, many of whose spectacular day/dusk-flying members are wasp mimics (an unrelated bunch of moths, also called clear-winged moths, includes the hummingbird moths in the Sphinx family.  Both groups have scale-less, transparent areas on their wings).  Sesiid caterpillars love to bore in wood or in plant stems, and the SBM’s stems of choice are melons, squashes, cucumbers, pumpkins, etc. (adults drink nectar).  They are rarely a pest in large agricultural situations where pesticides are used, but they can be a scourge to home gardeners.

 

Squash-borer moths

Squash-borer moths

As plants begin to bloom, the female zigzags around a field, laying eggs on stems, leaves, vines, petioles, and at the base of the plant, and the larvae that hatch toward the top of the plant make their way to the base before entering the stem/vine to feed http://bugguide.net/node/view/426659/bgimage.  They interrupt the flow of nutrients and water, causing the vine to wither, and by the time the withering starts, it’s too late to do anything about it (watch the stem for holes plugged with frass instead).  They feed within for a month, growing to an inch or so in length before leaving the stem and burrowing a few inches into the ground to pupate in a cocoon they spin of silk.  In the wild, SBMs use wild members of the gourd family, and they’ve been seen on milkweed.

 

Kate Redmond, The BugLady

Bug o’ the Week – Two-marked Treehopper

Howdy, BugFans,

2-mrkd treehppr Vib12 5b

The BugLady gets a kick out of these thorn-mimicking Two-marked treehoppers (Enchenopa binotata) (“two spots”); there’s something both dignified and comical about the cut of their jib.  Treehoppers are in the family Membracidae; the Greek word “membrax” meaning “a kind of cicada.”  Taxonomically, they are not far removed from cicadas; behaviorally – in the “how-in-the-world-did-the-early-namers-know-that?” category, treehoppers communicate with their prospective mates vocally, making what is described as a “cicada-like whine” that is inaudible to our naked ear. “Tree hopper?”  The odd source does mention that they hop (the closely-related leafhoppers sure do), and adults can fly.

 

There are about 3,200 species of Membracids, a.k.a Thorn bugs, in the world, and more are being discovered every day in the secluded canopies of rainforest trees.  They’re a tropical-temperate bunch, with zero species on Antarctica, only three more than that in Europe (one of which is the accidentally-imported American buffalo treehopper), and 266 species in North America.  They’ve have been around for at least 40 million years.

buffalo treehppr13 1

Buffalo treehopper

 

2-mrkd treehppr X14 10brzTreehoppers have a pronotum (the top part of the first segment of the thorax) called a helmet that is enlarged and can be pretty fancy http://bugguide.net/node/view/174830/bgimage, http://bugguide.net/node/view/552781/bgimage, http://bugguide.net/node/view/571292/bgimage, especially in the tropics http://grist.org/list/the-brazilian-treehopper-is-the-creepiest-raddest-insect-you-will-ever-see/.  Their first two pairs of legs are flattened, and their eyes are lovely, and you generally can’t tell males from females at a casual glance.  A two-marked leafhopper is about ¼” long.

 

Both nymphal and adult Membracids tap into the stems of woody and herbaceous plants with their beaks and feed on the sap, and treehopper species are often closely associated with a single food source.  Some species gather in groups as adults or nymphs.  Some have mutualistic relationships with ants (mutualistic means that everybody’s happy), which protect them in exchange for sweet honeydew (the two-marked treehopper seems not to be tended by ants).  Maternal care of eggs and even nymphs is seen in some species.  Most American species fly under the Exterminator’s radar, except for a few species that do minor damage to trees during egg-laying, when the female saws into a stem or bud in order to deposit an egg, and a few more dine on agricultural crops.  Tropical treehoppers can impact cacao and coffee crops, among others, and may be vectors of plant diseases.  One species is so spiny that going barefoot in its vicinity is not recommended.

 

The 2-marked treehopper, famously (among taxonomists, anyway), is a species complex (more about that in a sec).  2-MTs hew to the basic family plan, feeding on sap of specific plants.  They slit the bark of their host plant to deposit eggs within, covering the eggs with a secretion called “egg froth” that provides protection from desiccation in winter, may shield the eggs from predators, and that contains an attractant pheromone that brings other ovipositing females to the spot (where, like cows, they may line up, all facing the same direction).  The eggs hatch in spring when they are re-hydrated by the rising sap of the host plant as its buds open and its shoots start to grow.  The nymphal stages are awesome http://bugguide.net/node/view/196610/bgimage.  There is one generation in Wisconsin.

 

And here’s where things get interesting.

 

The 2-MTs are a well-studied species complex, kind of a continuum of eleven (or more) very closely related species that look alike and yet don’t interbreed.  Some species complexes occur geographically, with species replacing each other from east to west or north to south.  In the case of 2-MTs, several species can exist in the same geographical area, never meeting up with each other because they have different host plants.  They all have the same scientific name, followed by their host name.  This is Enchenopa binotata Viburnum (it likes Nannyberry).  If a male is forced to court from a non-host plant, he will sing his typical song, but he will signal less and the signals will be shorter.  If a female is forced to oviposit on a non-host plant (a “host shift”), she will lay fewer eggs, and both the hatching success and the nymph survival will be lower, but they will respond to the phenology of the new host (and a new species may be in the works).  2-MTs are evolving before our eyes, and with DNA analysis, our ability to separate them correctly is also evolving.

 

Adults can fly, and they do end up on non-host plants, staring at similar-but-different 2-MTs.  One study by Cocroft, Rodriguez and Hunt demonstrated that although more than 40% of courtships were initiated between different species of 2-MT, only 6% of the matings were between heterospecifics (members of another species).  Why? Behavioral isolation (signals that don’t match) trumps (and reinforces) ecological isolation (host plant/host plant phenology).

 

How does that work?  Boy and girl 2-MTs get together via a duet that he initiates.  According to Cocroft, et al, a male advertises his species via his song, producing a whining sound followed by pulsing that is transmitted through the substrate – through the stems and petioles of the plant he sits on.  He may sing sitting still or moving around or he may join a male chorus.  If she likes what she hears, a female will insert her own voice, allowing him to find her.  There is some individual variation in the sounds produced by males of her species, but the female “trains” males to stay with a range that she recognizes; different species on different host plants don’t interest her.  It gets even better – almost a quarter of the variability of his signal results from slight differences within the genotype of his host plant species.

 

Cocroft, Rodriguez and Hunt also wondered if the bugs’ vibrations “carried” differently on host vs non-host plants, and it turns out that a species’ vibrations transmit best on its ancestral host plant and are filtered differently by non-host plants.  2-MTs also use their voices to signal alarm.

 

About the blunt-horned treehopper (X).  The BugLady found several in close proximity to the adults on viburnum.  When she tried to match the image to one at the bugguide.net site, she found the following note from an expert:  “I also took a specimen like this – but in Nova Scotia. There is a slight possibility that this is an undescribed species, but a greater probability that it represents an abnormal reduction of the ‘horn.’ Please try to find the host, and watch for others.”  Exciting times!

 

Odd treehopper factoid – various treehoppers form mutualistic relationships with a variety of other animals, including ants, to whom they signal, via vibrations.  In Madagascar, some species of treehopper exchange signals with/enjoy a relationship with a few species of geckos, which are also allowed to harvest honeydew.

 

The BugLady

End of Year Letter from Jessica

I once read a book titled, “How to Poop in the Woods.”  I was on the eve of embarking on my very first backpacking trip – up to the Porcupine Mountains in the U.P. – with a group of three co-workers.  I was 22 years old and had absolutely no idea what the heck I was doing.   Yet, I was going to help co-lead this trip in a couple of weeks.  We all thought I should have some idea of how to, err, poop in the woods.  That trip, full of traverses of flooded rivers, good company around the campfire, and acres and acres of forests, brought me to my real home—the natural world.SAMSUNG DIGITAL CAMERA

This past summer, 15 years after that homecoming, my eight-year-old daughter, Aspen, and I waded in the Milwaukee River to catch crayfish. Her friends were there too as part of a week at Riveredge’s Trailblazers camp.  Throughout the summer she flipped upside down on ropes from the tree tops, swung—splashing and giggling—into  the river, and slid down the mud covered otter slide – all on this 379 acres of land so many Riveredge Kids call home.

The impact of Riveredge can be measured in so many ways, from the research made possible by our protected habitat to the number of schools and students who visit every year. But, it is the stories of Riveredge Kids that illustrate the transformational impact of our work.

Caroline Mosley is one of those kids. Five year-old Caroline, always the last to pull her strainer out of the pond, spent her summers in Riveredge camps.  She interned with Riveredge educators while completing her undergraduate degrees in Environmental Science and German at Creighton University, and last year, as a graduate student at UW-Milwaukee School of Freshwater Sciences, she presented on Phosphorus Recycling by Quagga Mussels at Riveredge’s 1st Annual Research Symposium.  Caroline’s next adventure will be in Washington, D.C. She is one of students awarded the prestigious University of Wisconsin Sea Grant Knauss Marine Policy Fellowships. Come February, she’ll spend 12 months working at NOAA and learning how policy becomes science.

Her story, and that of today’s Riveredge Kids like my daughter, was made possible by the vision and dedication of the handful of people who founded Riveredge in the face of encroaching development. We are privileged to be stewards of their legacy. It was their leadership that made Riveredge a pioneer in environmental education and a destination for best practices in environmental restoration. Of course, the human impact of their work can be seen in the 250,000 ‘Riveredge Kids’ who, since 1970, have discovered the natural world by wading in the Milwaukee river, sweeping the prairie, and  tapping the sugar maples.

Their vision and your support is the foundation for the future of Riveredge.  Join us in building on the Riveredge legacy. Make a year-end gift to the annual fund which pays for the yellow buses to bring kids to Riveredge, the purchase of pond strainers, the salaries of our educators, and the expanded adventure programming to engage a new generation of Riveredge Kids.

Make a difference today by supporting Riveredge. Together, we’ll help more kids find their home in the natural world.

 

Keep Smiling & Get Outside!

Jessica Jens, Riveredge Nature Center Executive Director

Why all the Orange?

orangeRiveredge Nature Center, in partnership with UW-Stevens Point and Treehaven Research Institute, is in the process of conducting a forest management study.   The orange markings on the trees, seen throughout the Riveredge sanctuary, indicate trees that are unhealthy or are negatively impacting the general health of our forests. 

Over the course of the next year, Riveredge will be actively managing portions of our forested landscape and determining how the forest responds to these management activities.  Future efforts will include removing dead ash (infested by the emerald ash borer), as well as trees that are diseased and/or impeding the health of the forest.

In addition to the active management activities, student interns will conduct research on changes of the flora within the forest due to these management activities.

Management Zones :

ManagmentZones

Oak/Hickory Forest: The oak/hickory forest is a distinct and major cover type in southern Wisconsin.  Now what was once vast oak savanna, prairie, and oak/hickory forest has been lost to development and agriculture. Management in this area will be mainly removing unhealthy and dying trees, while removing some species to help restore the stand and allow the remaining trees to thrive.

Oak Forest: This area will be managed to promote a healthy oak forest that will provide excellent wildlife habitat for years to come.  The lasting effects will be healthier trees that will provide more food and cover for wildlife.

Mixed Hardwoods: This area will be managed to promote and increase the diversity of the stand.  The closed canopy condition has prevented understory diversity and has limited the regrowth of other species.  By removing some of the dying White (Paper) Birch, sunlight will be allowed to reach the ground and allow for a variety of ground species to flourish.  The removal of other unhealthy and diseased trees will allow healthy trees to grow uninhibited and will allow light in to let seedlings and saplings grow into mature trees.  The large openings in and around the aspen are to allow for aspen regeneration to ensure aspen stay as a component of this stand for generations to come, while no conifers will be harvested, the increase in sunlight to the ground will allow for better regeneration of the conifers to increase the overall diversity.

Lowland Oaks:  In this area, the only trees that will be removed are the dying green ash, which are dying because they are infested with emerald ash borer. Emerald ash borer (EAB) is a beetle that bores into and eventually kills the ash trees it infests.  By removing these diseased and dying trees, we are opening up sunlight for other species like bur oak and white oak.  This will help  promote the oaks; creating an area that will be highly attractive to many wildlife species.

Sugar Bush: Riveredge Nature Center is known for its extensive sugar bushing operation.  In the areas where maple sap collection occurs, the management that is being implemented will allow the healthy maples to increase their crown diameter to help increase sap production.  Diversity will be maintained, but maples will be favored for the sugar bush operation.   Small canopy gaps will be placed to allow for the maple regeneration to grow and become the next generation of maples to be tapped.

 

For questions regarding RNC’s forest management plan, contact Mandie Zopp at mzopp@riveredge.us or call 262-375-2715.

 

Riveredge Gifts for the Holidays

Give the Gift of Pure Maple Syrup this Holiday Season! Grab a gift bag filled with Riveredge’s pure maple syrup and our very own pancake mix. Call Riveredge for information about shipping maple syrup gift boxes to family and friends through Dec. 18th. Download the order form here. 

We also have bunches of red osier dogwood for decorating as well as nature books, field guides, children’s books and many other nature related gifts.

All proceeds support Riveredge programs which foster a deeper understanding of the world for life-long learners of all ages.

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