Bug o’the Week – End of Summer Scenes

Howdy, BugFans,

Wow!  The first day of fall!  Much as she loves a nice fall day, the BugLady clings to summer (maybe that’s why she keeps buying peaches even though she knows she’ll be disappointed).  If you want to find bugs, look at flowers, so the BugLady has been searching the riot of wild sunflowers, asters, brown-eyed susans, and goldenrod.  Here are some of the bugs that have posed for her in the past month.

This mothy-looking CADDISFLY is actually not too distantly related to moths and butterflies.  Caddisflies’ aquatic larvae use silk to form a portable shelter from bits of vegetation or tiny stones (https://curious.royalbcmuseum.bc.ca/caddisfly-architecture/), though some skip the case and spin a net on a submerged rock so they can stay put in swift currents.  What are they good for?  Two words – Fish.  Food.  Fish prey on the larvae and on the emerging adults, and fly-tiers copy the caddisfly hatch https://www.orvis.com/p/slow-water-caddis/12a9.

Tiny (wingspread under an inch) EASTERN TAILED-BLUES have several broods throughout the summer.  They’re on the scene from May through September, and according to the Wisconsin Butterflies website (https://wisconsinbutterflies.org/butterfly), a few hardy individuals have been recorded into the first week of November!  In September, look for them close to the ground, ovipositing on white clover in mowed paths.  If your eyes are spry, you can see the contrast between their slate blue upper wings and their pale blue underwings in flight.

OBLONG-WINGED KATYDIDS should be green, right?  It turns out that color is negotiable in some Orthopterans (grasshoppers, katydids, etc.).  This species comes in brown, orange,

tan https://bugguide.net/node/view/273155/bgimage,

yellow https://bugguide.net/node/view/139882/bgimage,

and Pepto pink https://bugguide.net/node/view/126381/bgimage.

Here’s a paper about their colors https://blogs.scientificamerican.com/running-ponies/in-north-american-katydids-green-isne28099t-the-dominant-colour-pink-is/, and here’s what they sound like https://songsofinsects.com/katydids/oblong-winged-katydid.

A female SWAMP SPREADWING damselfly deposits eggs into a plant stem as the male guards her by clinging to the back of her head.

This small TREE FROG bit off a little more than it could chew.  It managed to swallow the front half of a meadowhawk dragonfly, but it doesn’t seem to have enough room to swallow the rear half.  Lots of roughage in dragonflies.

OAK SAWFLY LARVAE – If you turn over a partially-skeletonized oak leaf in summer, you may find these cute little skeletonizers, which look like slightly gooey caterpillars but are actually the larvae of members of a primitive wasp family.  They eat the tender leaf tissue and leave the tough veins, and the end result looks like a macramé project.

A MELOE BEETLE, a male, based on that crook in mid-antenna, descended the side of the log and joined another Meloe beetle, and hanky-panky ensued.  Meloe/Oil beetles, in the genus Meloe, are members of the blister beetle family.  “Oil beetles” because when they’re alarmed, they secrete oily drops from their joints that contain poisonous cantharidin, which causes nasty blisters on skin and does serious damage if taken internally.

AUTUMN MEADOWHAWKS are the last dragonflies of the season, able to survive a few light frosts and operate in daytime temperatures down to about 50 degrees (although by then, there’s not much prey in the air).  This one chose a backdrop of colorful dogwood leaves.

The BugLady found this handsome JUMPING SPIDER, Marpisa bina, at a nearby State Natural Area (thanks, as always, to BugFan Mike for the ID).  Not a lot is known about the 10 species in the genus, but most are wetland-dwellers.

Well-camouflaged CAROLINA LOCUSTS hunker on the trails, waiting until the BugLady practically steps on them before taking off on yellow-trimmed, black wings, and imitating, briefly, butterflies.

BUMBLE BEES, honey bees, and wasps of all stripes are abundant on flowers these days.  Honeybees maintain their hives throughout the winter, but bumble bee and paper wasp nests are annual affairs – started from scratch by new queens every spring.  The activities of the nest will cease with the frosts, but nobody’s told the workers.

MULTICOLORED ASIAN LADYBUG – Oh sure, it’s cute now, but pretty soon it will be looking for a way into your house https://uwm.edu/field-station/asian-multicolored-ladybug-redux/.

MONARCH – What would a late summer round-up be without Monarchs?  About a week ago, the BugLady walked the prairie trails at Forest Beach Migratory Preserve and saw 249 crisp, new Gen 5 monarchs (the migratory generation), most nectaring on asters and goldenrods, sometimes 10 or 20 butterflies on a single clump of plants.  Quality nectar plants are critical on the leisurely trip south – a newly-emerged Monarch has about 20 milligrams of fat in its body, but it needs to pack in another 100 milligrams of fat before it arrives in Mexico (trace that journey here https://maps.journeynorth.org/map/?map=monarch-peak-migration&year=2020).  These fat reserves sustain it during the winter (if you never click on any of the BOTW links, please try this one https://fstoppers.com/documentary/drone-disguised-hummingbird-captures-incredible-footage-monarch-butterfly-swarm-480714).

Go outside – it ain’t over until it’s over.

Kate Redmond, The BugLady

Bug of the Week archives:
http://uwm.edu/field-station/category/bug-of-the-week/

Bug o’the Week – Common Green Darners– a Love Affair

Howdy, BugFans,

We’ve had a major emergence of migratory Common Green Darners in the past 10 days.  They’ve been feeding along Lake Michigan’s western shoreline, zigzagging over the roadway and fields, socking away calories (those floodwater mosquitoes are good for something), and roosting in the cedars.  Pushed south by cold fronts, they’ll cover seven or more miles a day, and it will take them weeks to get to their destination.  They’re on their way, and maybe a little part of those of us who see them, goes with them.

Common Green Darners (Anax junius – “the Lord of June!”), hummingbird-sized dragonflies that, yes, sometimes attempt to prey on hummingbirds, have graced these pages before.  Here are some links to past episodes https://uwm.edu/field-station/common-green-darner-rest-story-family-aeshnidae/ and https://uwm.edu/field-station/dragonfly-swarm/, and a quick review.

Dragonflies have been around for 275 million years.  Back in the day (the Carboniferous and Permian day) some dragonfly ancestors had wingspreads of two-and-a-half feet and weighed a pound – crow-sized, according to the University of Nebraska-Lincoln’s Entomology website.  There was more oxygen in the air then, and that allowed insects and other invertebrates, which take in air passively through holes called spiracles, more oxygen to nourish their cells.  Think six-foot millipedes.

Wisconsin has two populations of Common Green Darners (family Aeshnidae), and because of that, they can be seen in our skies from May through September.  The migratory crew arrives in mid-spring, fresh from their winter range in the Southeastern US, Texas, and Mexico, one of about a dozen kinds of dragonflies that migrates out of the 400-ish species in North America.  They mate, oviposit, and die off, but as they do, the resident population starts to emerge from the warming waters.  There’s a big difference in the phenology of their offspring (called naiads – or nymphs, if you must – but never larvae).  Naiads of the migrant darners mature quickly, ready to emerge from beneath the water by late August.  Naiads from the eggs of the resident population, deposited in submerged plant stems throughout summer, take about 10 months to mature.

Darner swarm

Big assemblages of Common Green Darners – swarms – may be seen from early August on, depending on the weather.  An aquatic entomologist who blogs under the name of “Dragonfly Woman” collects reports of dragonfly swarms.  Dragonfly Woman divides swarming behavior into low-altitude, static (mostly feeding) swarms and higher-altitude migratory swarms (and she wants to hear about both).  Static swarms tend to be localized, with groups of dragonflies milling around no higher than about 20 feet off the ground.  Migratory swarms are fast-moving “rivers of hundreds of thousands of dragonflies all flying in a single direction and covering large distances.”  Both migratory and feeding swarms can contain a mixture of species.

Explanation: The BugLady’s first internet connection, back in the dawn of time, was dial-up, and she’s still traumatized by it (she used to start downloading a picture and go wash dishes until it was complete), so she tries not to send huge picture files.  The attached “darner swarm” picture is a big file, but if you can zoom it, you can see a feeding swarm of darners glittering over a low, wet field at the end of August.  How many?

At this time last year, the BugLady spent parts of three or four days on a hawk tower counting migrating raptors, surrounded by a river of dragonflies – tens and hundreds of thousands of dragonflies, from horizon to horizon, moving steadily south.  It was a religious experience.  Primordial.  The fall dragonfly migration is no secret from the raptors, and several species of falcons grab the darners out of the air and dine on the wing.

The BugLady visited Forest Beach Migratory Preserve recently on a windy day when the Common Green Darners, various mosaic darners, and Black Saddlebags did not want to be aloft; they wanted to shelter in the grasses and trees.  As she climbed a low hill, darners exploded from the conifers at the top, circled, and settled back down, and it seemed like every plant stem and tuft of grass hid a few.  What a thrill!  She walked around the trail apologizing to the darners for kicking them up, and laughing at herself, because even though she imagines that she has a pretty good “dragonfly search image,” they almost always see her long before she sees them (and she confesses that in one of the pictures with two darners in it, she didn’t see the second until she put the picture up on the monitor).  In one shot, you can scan the edge of the mowed path, as the BugLady does, except that most darners aren’t pre-marked by red “X’s.”

She has said it before and she’ll say it again – with apologies to major conservation organizations everywhere – she is more concerned about the fates of dragonflies and other insects than of giant pandas, cheetahs, elephants and grizzly bears.

Go outside, park yourself on the edge of Lake Michigan, and enjoy the show.  And report your dragonfly swarms at https://thedragonflywoman.com/dsp/report/.

Kate Redmond, The BugLady

Bug of the Week archives:
http://uwm.edu/field-station/category/bug-of-the-week/

Bug o’the Week – Shore Rove Beetle rerun

Salutations, BugFans,

The BugLady is getting close to 600 of these episodes (probably would have done a few things differently if she’d known).  Some are memorable to her because the writing has stood the test of time, others because the star of the show is a particular favorite, and still others because the bug turned out to be just so cool!  That has been the fun of BOTW – discovering the amazing and sometimes surprising design features and super powers that insects have.  The shore rove beetle was one of those.  The BugLady found it by accident 6 years ago while she was doing something else.  She hasn’t seen one since, but it just stuck in her brain.

Sometimes (often), the facts about an insect do not come tied up neatly with a bow, and the research seeps out of the realm of the six-legged and raises as many questions as it answers.

In early May of 2014, the BugLady was photographing Equisetum/Horsetail (because it’s such a neat plant) not far from a wetland edge.  Field horsetail (Equisetum arvense), a common roadside species, first raises a tan, non-photosynthetic, fertile stalk topped by a structure called a cone, which bears the spore-producing sporangiophores (modified leaves).  Spores are released, and this stage is followed by a sterile, green plant that looks like a mini-pine tree and that photosynthesizes, its energy stored in a perennial rhizome.  In other species of equisetum, the fertile cone is located on top of the sterile stem (for an equisetum side trip and The. Most. Awesome. Video. EVER! see http://blogs.scientificamerican.com/artful-amoeba/flying-for-free-the-horsetail-spore-way/).

The BugLady noticed that the tops of some of the cones had been grazed.  Who did it?  Based on the height of the truncated stalks, the likely suspects are rabbits or red squirrels.  The BugLady found a lot of information about the unwholesomeness of the sterile Equisetum plants for livestock, and about its medicinal uses, but not much about the fertile stalk.  The spores pack no nutrients for the future plant – they do contain chlorophyll and some moisture – they have to hit the ground running (pollen, on the other hand, is rich in nutrients).  Are the spore-producing tissues nutritionally desirable?  Similar structures in certain fungi contain lipids and proteins.  The fertile Equisetum plant has apparently been eaten (with caution) for millennia, and the cone is listed as “edible” in a few (very few) foraging books.

She was not expecting to see any Equisetum– insect interactions, and yet she observed a sawfly ovipositing into a horsetail stem (a story for another day), and she found this small rove beetle in the genus Stenus, doing — something.

Rove beetles (family Staphylinidae) comprise the largest beetle family in North America (in the World, maybe, with the possible exception of the weevils), and they are a very diverse bunch.  The US hosts more than 5,000 species of these typically small, slender, speedy beetles, with their much-shortened elytra (wing covers).  Although they may look wingless, their wings are folded underneath https://bugguide.net/node/view/170319/bgimage (like Origami, said one source), and they are good flyers.  When alarmed, they posture like a scorpion http://bugguide.net/node/view/885251/bgimage, but they’re harmless (well, except for the caustic/nasty-tasting chemicals that some deliver from the tip of the abdomen).  Their lives are often lived under the cover of leaf litter.

The genus Stenus is in the subfamily Steninae, the Water Skaters/Water Gliders, and they’re described as semi-aquatic.  It’s a large genus, with 167 North American species, and for once, the BugLady is not going to try to guess which.  Turns out that there a number of super powers residing in that bug-eyed little body.

So, what was this rove beetle doing on the Equisetum?  Not eating it (probably…) – these are carnivores (OK, the Peterson Beetle guide says “all are believed to be carnivorous”).  They make their living hunting springtails, mites, aphids, and other tiny invertebrates along the marsh and stream edges they inhabit.  Whether Stenus is eating the plant tissue or going after another invertebrate feeding there, it would seem to be taking advantage of a break in the cone that was initiated by something larger.

Watch a shore rove beetle in action at: https://www.youtube.com/watch?v=P_MB6GHlXJY&index=91&list=PLzr0J2sWC1QiypVYj-TSWGdOzJlTmvN7r

Stenus has developed a pretty awesome adaptation that increases its odds of putting food on the table – a mouth part (labium) that it can extend like a telescoping pole just by increasing the blood pressure to that area.  Springtails have pretty fast reflexes, and sources disagree about whether that they are too quick for Stenus to be successful consistently (and springtails are covered with slippery scales that are sacrificed if they get grabbed).

Rather than being a sharpened “harpoon,” the labium is covered with a variety of bristles and by pores that secrete a glue that sticks to about any surface.  When it scores a bulls-eye, the Stenus retracts its amazing mouthpart, pulling its prey up to its mandibles (which are described as “sickle-like”) and injecting pre-digestive juices that soften the hapless critter.  The BugLady likes to photograph mini-critters, but the Scanning Electron Microscope (SEM) does it better https://scrubmuncher.wordpress.com/2010/01/15/ravenous-rove-beetles/.  This highly specialized mouthpart seems to argue against herbivory.

Stenus also enjoys Better Living through Chemistry.  Some, but not all, members of the genus live in close association with water, where they are small enough and light enough to scoot across the surface film (at 2 – 3 cm/second) without breaking through.  In the event that they do perforate the surface film or if they need to move more hastily, they can release a hydrophobic (water-repelling) alkaloid called stenusine from the tip of their abdomen.  Stenusine spreads quickly and forcefully across the water’s surface, and the “equal and opposite reaction” is that the beetle shoots forward at speeds between 45 and 70 cm/second (the equivalent, say the people who did the math, of a human-sized beetle being propelled up to 550 mph).  After a few such squirts, the beetle must replenish its stock of stenusine.

But Stenus species that are not intimately associated with water also produce stenusine.  Why?  Stenus rove beetles groom themselves.  A lot.  And they spread stenusine and a few related chemicals all over themselves (it’s called “secretion grooming” – isn’t scientific terminology grand?).  Why?  Turns out that these substances are toxic to fungi and bacteria that might afflict the beetles, and they act as “feeding deterrents” for the beetle’s predators.

Final “Whys” of the day.  Stenus beetles also manufacture a chemical called cicindeloine; it’s part of the anti-predator/anti-microorganism cocktail.  There’s a (European) rove beetle with the name Stenus cicindeloides https://eol.org/pages/3386562 that looks like a cookie-cutter Stenus.  But chemicals are generally named after the organism that produces them, and Cicindelidae is the family name of the Tiger beetles,.  So, why is there a rove beetle species and a rove beetle protective chemical named for Tiger beetles?

A day in the life of a BugLady.

Kate Redmond, The BugLady

Here’s an electric blue Stenus from Asia https://commons.wikimedia.org/wiki/Category:Stenus_fretus#/media/File:Stenus_fretus_Cast._(3211755041)_(2).jpg.

Bug of the Week archives:
http://uwm.edu/field-station/category/bug-of-the-week/

Bug o’the Week – Floodwater Mosquito –an homage

Howdy, BugFans,

Homage: “something that someone does or says in order to show respect or admiration.” (Macmillan).  In this case, it’s a grudging tip of the hat – we may not appreciate them, but we acknowledge that they are very good indeed at what they do.

The BugLady struck a deal with mosquitoes a very long time ago – she doesn’t bite them and they don’t bite her (alternatively, as one of her offspring suggested, she may just be tough and sour).  The only species that didn’t sign off on the pact, and the only species that raises a welt on her, is what she’s always called the “August mosquitoes” – the small, aggressive floodwater mosquitoes that seem to be biting with one end before they’ve fully touched down with the other.

There’s been a lot of rain in the BugLady’s corner of Wisconsin lately (including a localized 7” deluge that drowned the BugLady’s car in its parking lot, a story for another day).  Ample rain in the weeks before that had given the floodwater mosquitoes a start.  The BugLady will be trying to squeeze in a lot of trail time now, in an attempt to beat the inevitable population explosion.

Floodwater mosquitoes made the news here in 2018, when a dry July was followed by massive rainfall in August, which was followed by a massive mosquito hatch that made September miserable.  School groups that traveled to the local Nature Center for outdoor experiences were begging to go inside after only 15 minutes outside.

With some insects, you look at the common or the scientific name and wonder about the story behind it.  Not so with the floodwater mosquito/inland floodwater/freshwater mosquito.  The common names are pretty straightforward; the scientific name Aedes vexans comes from the Greek aedes, meaning odious or unpleasant and the Latin vexare, meaning “to annoy, torment, or harass.”  A century ago, it was called Culex sylvestris, the swamp mosquito.

They’re found in damp areas on five continents (they haven’t discovered or been inadvertently carried to Hawaii, Antarctica or South America yet), and they’re less common in far southern, far northern, and high-altitude North America.  Their needs are simple – food, in the form of nectar (him) and the blood of a large mammal (her), shelter, and a suitable place to deposit her eggs.

Males https://bugguide.net/node/view/1340555/bgimage, of course, are strict vegetarians, feeding on nectar and honeydew.  Females also consume carbs, but she needs protein from a blood meal in order to form eggs https://bugguide.net/node/view/11025/bgimage.  Larvae https://bugguide.net/node/view/1751200/bgimage eat bacteria and other tiny goodies they find in the water and on underwater surfaces.  For a Mosquitoes 101 review, see https://uwm.edu/field-station/the-mighty-mosquito/.

Their egg-laying protocol, which is typical of the genus, calls for the female to gamble.  She lays around 150 eggs, placing them on the ground, one at a time, near water at damp, grassy edges and in roadside ditches and depressions – spots that are destined to get wet – rather than directly into standing water like most mosquitoes.  She makes her choice based on her read of the existing soil moisture and on the presence of enough leaf litter to keep the soil damp until it floods.  When these areas become pools after a rain, her eggs can hatch into aquatic larvae within a week and emerge as adults in another week, especially in warm temperatures.  There are multiple generations per year, and they are with us throughout the mosquito season – one exterminator says that at any given moment, 40% to 50% of mosquitoes on the wing are floodwater mosquitoes.  The final generation overwinters as eggs, ready to get down to business the following spring.  Adults live for three to six weeks.

And if it doesn’t rain?  No worries – her eggs can dry out and wait for years for the right conditions to come along and rehydrate them.

Unlike other mosquitoes, floodwater mosquitoes are no stay-at-homes, traveling ten miles and more from breeding sites.  They are certainly tenacious – one sat on the BugLady’s wrist as she changed camera lenses so she could take its picture – denim does not faze them, and, they’re hard to photograph because most of them head directly for the ears, face, and neck.

When it comes to the floodwater mosquito’s epidemiological reputation, the reviews are mixed.  Aedes is a largely tropical/subtropical genus that contains some notorious disease-spreaders.  One source was relieved that, since there are so darn many of them, floodwater mosquitoes don’t carry diseases (on this continent).  Other sources say that they have the genetic potential for carrying several kinds of encephalitis, Zika, and West Nile Virus (and have transmitted them under laboratory conditions), but they are not a factor in transmission in the field.  Still others say that they do spread these diseases, plus dog heartworm, but they are “secondary vectors” – that is, other mosquito species, notably Culex species, do the heavy lifting and the floodwater mosquito simply dabbles.

Who would have guessed that laying eggs on land would be a successful strategy for mosquitoes!

Kate Redmond, The BugLady

Bug of the Week archives:
http://uwm.edu/field-station/category/bug-of-the-week/

Bug o’the Week – Summer Scenes

Howdy, BugFans,

 

It’s High Summer, and a lot has been going on out there.  Many species have already peaked and disappeared from the scene, assuming, until next year, whatever form they spend the majority of their lives in.  Others are coming into their own.  Here are some of the sights the BugLady has seen in local prairies and wetlands.

ANTS are everywhere, foraging for proteins and carbs, including milkweed nectar to take home to their families.  Some species of ants have workers that are essentially tanker trucks.  Ants are no great shakes as pollinators, due to their slippery little bodies and fastidious grooming habits, and besides that, they’re pedestrians, so the pollen doesn’t travel far.  (Family Formicidae)

BLUE MUD DAUBER WASP – Cup plants have “perfoliate” leaves that look like two “conjoined leaves” but are actually a single leaf whose base is joined around the stem, making it look like the stem is piercing it.  For a few days after a rain, reservoirs made by the cup plant’s leaves hold water that’s appreciated by all sorts of small animals.  The wasp uses mud to construct chambers for her eggs, but she doesn’t carry water to dirt, spit on it, and stir.  She may just be thirsty.  (Family Sphecidae)

STRIPED HAIRSTREAK – The BugLady found this small butterfly of dappled woods and edges while she was surveying water hemlock plants for an up-coming episode.  Adults nectar on available flowers, and Butterflies of the Great Lakes Region tells us that “Early in the morning, they will sip dew from leaves as they bask.”  They’re not-very-common – “scattered lightly over our landscape,” says “The Butterflies of Massachusetts” website, “widely distributed although nowhere abundant.”  The theory is that the eyespots on the hind wing confuse predators.  (Family Lycaenidae)

HORSEFLY – Just a glamour shot of a horse fly, that’s all.  (Family Tabanidae)

PARASITIZED – This dangling caterpillar was discovered in its infancy by a small, parasitic wasp that laid an egg in it.  The wasp larva hatched, and then it ate and grew within the caterpillar, which was trying to do the same, but whose existence had been repurposed.  When it was ready to pupate, the wasp dealt the coup de grace to its unfortunate host, exited, and spun a cocoon on the outside.  As Darwin once said of parasitoids, “I cannot persuade myself that a beneficent and omnipotent God would have designedly created the Ichneumonidae with the express intention of their feeding within the living bodies of Caterpillars.

AMERICAN CARRION BEETLE – The BugLady has seen a number of adult carrion beetles flying around –black and yellow and big and buzzy – trying to convince her that they’re bumble bees, but she rarely sees the larvae.  Adults lay their eggs on dead animals, and then stick around on the carcass doing “pest control” (eating the competition) before their well-armored larvae hatch and for a while afterward.  The larvae will also eat other larvae they find on “their” carrion.  (Family Silphidae)

EASTERN AMBERWING – The BugLady’s favorite insect is the Tiger Swallowtail, but the Eastern Amberwing is on her long list of second-favorites.  This feisty 0.9” dragonfly has an attitude way bigger than its size.  (Family Libellulidae)

A JUMPING SPIDER in the genus Pelegrina (thanks as always for the ID, BugFan Mike) is another critter with attitude.  You can see why jumping spiders have fan clubs.  (Family Salticidae)

COMMON BUCKEYE – The BugLady has way more shots of this beautiful butterfly sitting on the ground than on flowers (when it sits on flowers, it prefers composites); it typically flits along 6’ ahead of her on mowed paths.  It’s a Southern migrant to God’s Country, arriving in early summer, but the migrants produce a brood once they’re here.  The undersides of the wings of the migrants https://bugguide.net/node/view/1460171/bgimage and the later/fall broods https://bugguide.net/node/view/1301685/bgimage are different – if you’re lucky enough to see one with its wings closed.  If the Striped Hairstreak’s eyespots are meant to confuse, the Buckeye’s are meant to intimidate. (Family Nymphalidae)

CINNAMON CLEARWING MOTH – So cool!  So speedy!  Clearwing moths are in the Sphinx moth family Sphingidae; we have two species around here, and the BugLady has plenty of out-of-focus shots of each.  Like chasing sprites.

ROBBER FLY – Some robber flies are small and shy, but Promachus vertebratus is neither.  At about an inch long, it was almost the same size as the Halloween Pennant dragonflies the BugLady was photographing at the same time.  It makes “annoyed” sounds when you kick it up in the fields (attitude again).  These flies prey on anything they can catch – the BugLady has a shot of one holding a Clouded Sulphur butterfly.  (Family Asilidae)

WHITEFACE AND BLUET – The BugLady was stalking dragonflies at Spruce Lake Bog when a Dot-tailed Whiteface dragonfly grabbed a Marsh Bluet damselfly and sat down beside her.  Something buzzed the duo loudly – maybe a robber fly – and the startled dragonfly released its prey.  As the whiteface moved to a different perch, the damselfly shook it off and flew away.  No damselflies were harmed to make this picture.  (Families Libellulidae and Coenagrionidae)

 

Go outside – look at bugs!

 

Kate Redmond, The BugLady

Bug of the Week archives:
http://uwm.edu/field-station/category/bug-of-the-week/

Bug o’the Week – Dragonhunter

Greetings, BugFans,

 

Dragonfly July is drawing to an end.

 

The BugLady’s younger daughter and her friends have been taking to our northern woods and lakes this summer (where the cool bugs are), and she’s sent tantalizing pictures of her encounters.  A large Emerald dragonfly perched in the middle of her campsite, a spectacular darner, and this guy, a Dragonhunter, which apparently checked them out as they paddled, sat on a kayak, and even sat on one of the paddlers.  Shout-out and photo credit to BugFan Laurel.

The BugLady thinks of this species, like loons, as the voice of the north woods, and while it is true that it occurs in the northern half of Wisconsin, its range actually extends from the Maritime Provinces to Manitoba to Texas (except for southern Wisconsin/northern Illinois and the south end of Florida).  Look for it along sunny rivers and streams with a moderate/fast current, on lakes and bays, or foraging over open roadways or along woodland edges.

 

This is one spectacular dragonfly, and everything it does is larger than life; Kurt Mead (Dragonflies of the North Woods) calls it “a legendary insect.”  It is 3 ½” long and is often called our bulkiest/most massive dragonfly.  Its coloring is a stark yellow and black with black legs and black-veined wings (its naiad is unique, too).  Its behavior is aggressive – and inquisitive – and its choice of prey is startling.  Even its pedigree is unusual.  The Dragonhunter, aka the Black Dragon (Hagenius brevistylus), is the largest of our clubtails (family Gomphidae) and is an American specialty, the only member in its genus (its closest, relatives, equally large, are in the genus Sieboldius on the Asian continent).

Here’s what they look like when they’re not perched on the bow of a lime green kayak – an adult male https://bugguide.net/node/view/262939/bgimage, an adult female https://bugguide.net/node/view/1149299/bgimage, and a face to face https://bugguide.net/node/view/732248/bgimage.  The club at the end of the abdomen is pretty narrow, and the downward-curved tip of the abdomen is typical, even in flight.

Their long, strong wings allow them to chase fast-flying prey (they can hit about 25 mph) and their legs are equipped with stout spines so they can hang onto it.  Legler, in Dragonflies of Wisconsin, says, “When feeding it perches on dirt roads waiting for other dragonflies, including darners, to fly down the road. The Dragonhunter then swoops up after the darner from behind. Or it may perch on branches high in treetops. It then swoops down on passing dragonflies and back up to the treetop to eat.”  Dragonflies (sometimes even other Dragonhunters), make up a respectable proportion of their menu (here’s one with a Widow Skimmer https://bugguide.net/node/view/905550/bgimage).

 

So, too, do large butterflies https://bugguide.net/node/view/1104558/bgimage.  One author reported seeing a pile of swallowtail wings beneath a perch frequented by a Dragonhunter, and they also hunt for monarchs, especially when monarchs are numerous.  Monarch butterflies, of course, are poisonous due to the milkweed sap they ingest as caterpillars; the highest levels of toxins are in their wings, but the Dragonhunters discard those, preferring the butterfly’s thorax and abdomen.  When pressed by Dragonhunters, monarchs change their behavior, eschewing their preferred sunlight and feeding in the shade that Dragonhunters avoid.

 

And then there are hummingbirds.  The BugLady found a note in the journal of a Welsh dragonfly society about one of its members who, while on vacation in Canada, came across a Dragonhunter attempting to subdue a Ruby-throated Hummingbird that was about the same size.  He managed to separate them (carefully and with some difficulty) and they went their separate ways (Yes, there’s a picture.  Scroll down. https://www.cofnod.org.uk/OpenCalendarFile.ashx?ID=1122&AspxAutoDetectCookieSupport=1).

 

They seem impervious to the stings of bees and wasps, which they also catch.

 

The dark, quarter-sized naiads https://bugguide.net/node/view/1640761/bgimage, disguised among the fallen leaves on the river’s floor, eat small invertebrates including other dragonfly naiads, and young amphibians and fish.

 

Male Dragonhunters are territorial, showing off along the sunny edges of their waterways.  They mate in the treetops https://bugguide.net/node/view/302261/bgimage and don’t do a lot of tandem flying, and the female often emerges from the experience a little the worse for wear (as Ohio nature writer Jim McCormac says, “The courtship is Neanderthalish, no gentle New Age insect here.”).  Males have short, strong claspers, and his firm grasp often punctures her head or eyes.  Both male and female are polygamous.

 

Females fly across short stretches of open water, ovipositing by tapping the tip of her abdomen into the water or by tossing eggs in from above (Legler again, “Or, most remarkably, she sometimes swings her abdomen rigidly like a golf club knocking little a globule of eggs and water up onto the bank!”).  Eggs are gel-covered and sticky and are soon camouflaged by a layer of silt.  The naiad stage is a long one, lasting from four to seven years, depending on the water temperature, and not surprisingly, the naiads are pretty freeze-tolerant.  Like some other clubtails, they stage large, synchronized emergences in early summer, with naiads leaving the water en masse and crawling up onto the shore and even up tree trunks https://bugguide.net/node/view/23665/bgimage.  Adults live about three months.

 

Females are colored similarly to males, and unlike many other dragonfly species, are found around the water when not breeding (no one messes with her).

 

The Twentieth century brought an unneeded complication into the lives of Dragonhunter naiads, in the form of alien zebra mussels, immigrants from Europe that like to fasten to stationary objects (for more about zebra mussels see https://uwm.edu/field-station/a-tale-of-two-mussels-the-one-two-punch/).  Their round, flat shape and the fact that, unlike other clubtail species, the naiads don’t burrow makes them an attractive substrate to the mussels.  A small load of mussels doesn’t affect the naiad’s feeding but can hinder its final molt.

 

Paulson, in Dragonflies and Damselflies of the East, says that “Adults at water usually approachable” https://bugguide.net/node/view/706067/bgimage, and the Dragonhunter is sitting on the kayaker’s head, and that brings us to the BugLady’s friend Joe, who walked to the shore of a northern lake, put out his hand, and a Dragonhunter came in and sat on it.

 

Kate Redmond, The BugLady

Bug of the Week archives:
http://uwm.edu/field-station/category/bug-of-the-week/

Bug o’the Week – Powdered Dancer

Howdy, BugFans,

The BugLady is a frequent visitor to the Milwaukee River at Waubedonia Park in July, because that’s where the magic is.

Arrow Clubtails make their maiden flights up into the trees just 45 minutes after emerging from their nymphal skins (leaving the skins – exuvia – as signs of their passing).

arrow clubtail exuvia

Arrow Clubtail exuvia

Arrow Clubtail

Silvery, new Stream Bluets cling to plants while their elders fly in tandem;

Stream Bluet

Stream Bluet pair

Common Whitetails chase everything;

Common Whitetail

and incomparable Ebony Jewelwings teeter on reeds.

Ebony Jewelwing

And the number of American Rubyspot pictures that she’s taken there this year may be a personal best.

American Rubyspot

But – oh my – the Powdered Dancers!

The first time she walked the shoreline six years ago the river was low, and mats of Potamogeton (pond weed) undulated on the surface about 10 feet offshore.  And on those mats were ovipositing pairs of Powdered Dancers – slender damselflies taking their chances on a big river.

Along with bluets, sprites, and forktails, dancers are members of the Pond/Narrow-winged damselfly family Coenagrionidae.  At 1.5” to 1.7” long, Powdered Dancers (Argia moesta) are both the largest in their genus and the largest in their family.  Argia, inexplicably, comes from an Ancient Greek word meaning “laziness” (but they aren’t), and “moesta” means sorrowful, a possible reference to wearing ashes in mourning.

Powdered Dancer

Don’t look for Powdered Dancers around the edge of a pond – this species is found next to running water or on the shores of large lakes, especially where there are emergent rocks to sit on.  Their color camouflages them there and so does their habit of sitting with their wings folded at their sides rather than over the abdomen, which gives them a lower profile.

Pruinosity puts the “powder” onto Powdered Dancers.  As they mature, males produce tiny, waxy plates that coat their exterior and turn them from dark to pale (see the first picture in this series http://southwestdragonflies.net/damsels/PowederedDancerPierreDeviche.html).  Females come in brown and blue morphs, and they also change color during their three or four weeks as adults.  Blue morph females https://bugguide.net/node/view/1402906/bgimage look like Blue-fronted Dancers https://bugguide.net/node/view/1724345/bgimage, and brown form female Powdered Dancers https://bugguide.net/node/view/1713039/bgimage look like brown form female Blue-fronted Dancers https://bugguide.net/node/view/1573201.

Paulson, in Dragonflies and Damselflies of the East, speculates that “Perhaps pruinosity confers resistance to high temperatures, as this may be the only odonate active at streams on sunny days exceeding 37 degrees C.” (When the BugLady was in grade school in the ‘50’s, her teachers said “Learn the metric system – the US will be switching any day now.”  37 degrees is a scorching 98.6 degrees F.)

Back to the river.  Studies show that even though they are somewhat territorial, pairs of Powdered Dancers are attracted to floating leaves that have other pairs of Powdered Dancers already ovipositing on them.  It’s called an “oviposition aggregation.”  The presence of multiple pairs may cut down on harassment by unattached males and by predators, and also on the time a pair may search for a suitable spot to oviposit (which Paulson lists as 3 to 49 minutes).  Researchers found this out by populating floating leaves with tiny models of Powdered Dancers, some resting, some coupled.

In many species where the male contact-guards the female (maintains his hold on the back of her head) as she descends to insert eggs into/onto underwater vegetation, he is not quite as committed to total immersion as she is and will release her if she goes too deep.  Powdered Dancer males seem to be all in.  It’s not clear why – the dangers he is guarding her from are in the air.  Look at the picture that shows a few partly-submerged pairs at the left, and then look to the right for several pairs that are completely underwater (when he saw the picture, BugFan Bob said that there are some “Maybe this is deep enough” conversations going on down there) (he said some very scholarly things, too).

Pairs can stay under for an hour or more and have been found more than a yard (meter) below the surface.  The naiads https://bugguide.net/node/view/1380567/bgimage hide under stones and debris and overwinter in a late-stage, crawling out of the water to emerge as adults early the next summer.

Powdered Dancers are active, but they stay at home in a relatively short stretch of the river bank; and while females and immatures may fly inland, mature males seldom stray far from the water.

Damselflies eat other invertebrates, both underwater as naiads and in the air as adults.  Female Powdered Dancers are avid hunters whose diet includes other damselflies, even other Powdered Dancers.

Fun Powdered Dancer Fact: researchers in Ontario found midge larvae hitchhiking (harmlessly) on Powdered Dancer naiads, a phenomenon called phoresy.  The probable advantages for the midge larvae are a larger, more stable port in a current, and they don’t have to use as much energy moving around.  The damselfly naiads are not affected by the arrangement.

Kate Redmond, The BugLady

Bug of the Week archives:
http://uwm.edu/field-station/category/bug-of-the-week/

Bug o’the Week – Spatterdock Darner

 Howdy, BugFans,

The BugLady had a great June, hitting the trails and photographing insects.  Not surprisingly, many of the insects that wandered past her lens were dragons and damsels, so “Closed for June” may morph into “Odonates for July.”

Isn’t this a spectacular animal!!!  BugFan Freda (aka the Dragonfly Whisperer) found it and then showed it to the BugLady.

A few words about Freda’s discovery.  First, she wasn’t looking for it, and the spot where she found it does not look at all auspicious from the road (it’s a tiny, gravel parking lot surrounded by shrubs and small trees).  She stopped and looked because … well … because she did.  The BugLady suspects that Freda is tuned into the zinging of the Cosmos.

Second, the Spatterdock Darner isn’t even on the list for the county she was in (find county lists under the map icon at the lower right-hand corner at http://wiatri.net/inventory/odonata/).  In fact, it’s only been recorded in a few counties in the central and southeastern parts of Wisconsin.

Third, as she explored the vicinity a little more, she found more Spatterdock darners, possibly breeding, and she found another unlisted darner.  The moral of the story is that we should, metaphorically, stop and smell the roses/odonates.  If our travels take us by that low spot in the road where a guard rail marks a little pool or stream, or past a big swamp where we always see dragonflies in the air, we should pull off and take a look (with a nod to poison ivy, ticks, mosquitoes, deer flies, soft shoulders, and No Trespassing signs).

Spatterdock, AKA Yellow pond lily and Bullhead lily (Nuphar advena), is a floating-leaved aquatic plant that’s rooted in the bottom of the pond.  Spatterdock Darners AKA, Spring Blue Darners (Rhionaeschna mutata), are dragonflies in the family Aeshnidae.  Until 2003 they were classified with the mosaic/blue darners in the genus Aeshna (to review “mosaic darners,” see this episode about the Green-striped Darner https://uwm.edu/field-station/green-striped-darner/), but now they’re in a genus of tropical darners.

[Short grammatical aside:  the “c” in the genus name keeps popping in and out.  Absent in family Aeshnidae; absent in the genus Aeshna; present in darner genera RhionaeschnaBasiaeschna, and Gomphiaeschna.  It’s not just the BugLady’s capricious spelling.]

This is a big dragonfly, up to 3” long, that one source described (perhaps unnecessarily?) as “very blue.”  Its eyes are distinctive (but are shared by the equally-awesome Blue-eyed Darner http://wiatri.net/inventory/odonata/SpeciesAccounts/SpeciesDetail.cfm?TaxaID=170, a genus member that is also a Wisconsin rarity).  Females are slightly duller in color, and there are some brown form females.  Also distinctive is its flight period – as one of its common names suggests, this is an early dragonfly, aloft in Wisconsin from late May through June, before most of the mosaics that it could be confused with.

They’re found over a pretty large chunk of geography – Ontario to Kentucky, and then west to the Mississippi River – but they aren’t common anywhere within that range.  Their global conservation status is listed as “secure,” but they are considered endangered or threatened in most of the states where they occur.  Ontario Odonata calls them “one of Ontario and Canada’s rarest dragonflies.”

Habitat plays a role in that story.  Although they not as closely linked to water lilies as Lilypad Forktails are (https://uwm.edu/field-station/a-species-on-the-march/), they will use water lilies if they’re available.  Their habitat requirements are narrow – for reproduction, they prefer shallow, peaty, fish-free ponds, backwaters, open marshes, boggy waters, and sometimes ephemeral wetlands with lots of aquatic vegetation and with woody edges, and they don’t stray far away from those spots as adults.  Such wetlands used to be more common, but early settlers in this and other states put a lot of energy into draining and filling them.  Presumably, the species is rare in Wisconsin because it is new here and is just establishing populations.

It’s hard to make management plans for a species when we just don’t know that much about them.  Spatterdock Darner populations can be scarce and local – and transient – disappearing from sites they had previously occupied.  In one study, Minnesota researchers failed to locate them in an area where they had been reported just a year before, despite searching 25 likely wetlands in the area.  The researchers suspected that fish may have been introduced (not necessarily by humans – waterfowl carry fish eggs on their feet and in their guts) and were eating the naiads, but changes in water chemistry, pollution, oxygen levels, sediment, ground water, etc. may also have affected the breeding sites.

Much of what we know about Spatterdock Darners comes from the observations of Edward Bruce Williamson, a Michigan banker who was, in the early days of the 20th century, an acclaimed dragonfly expert.  He found Spatterdock Darners while surveying Vanemon Swamp in Indiana.  Writing for the Entomological News (July 8, 1908) he said, “In Wells County, Indiana, are a few remnants of a the old swamps which fifty years ago made the chills and ague of this county a constant menace to the early settlers and a perennial joke for those too wise to invade such an inhospitable wilderness.       On June 23 [1907] I was at the marsh early in the morning.  As soon as I arrived I noticed Aeshnas flying low over the marsh.  A small patch of spatterdock in open water was repeatedly visited, the Aeshnas flying slowly in and out, with much stationary fluttering among the leaf stems.      On bright mornings when the eastern sky was clear they were hunting over the west side of the marsh at 4:45 o’clock.  One cloudy morning they did not appear at all.  After 9 or 10 o’clock their visits to the marsh were rare and they were more wary, leaving the marsh when any attempt was made to approach them and flying directly to or above the tree tops.  Aeshna mutata spend most of the day after 9 or 10 A.M. either resting in the trees or flying about over the tree tops, probably the latter.”

[He also wrote that “In early spring dainty crustaceans (Brachypus vernalis) [fairy shrimp] in half invisible schools pulsate their aimless ways.”]

Adults catch flying insects in sunny patches at wooded edges, and males patrol for females over open water or along its edges.  In Dragonflies through Binoculars, Dunkle says that “Males patrol low over the vegetation with a leisurely, erratic flight for 10 to 15 minutes at a time, paying special attention to flowers of plants such as spatterdock.”  According to the Massachusetts Division of Fisheries and Wildlife’s Natural Heritage and Endangered Species Program, “Spatterdock Darners are active on sunny days. Males patrol breeding sites, typically flying lengthy beats several feet above the water’s surface.  When more than one male is present, aggressive interactions are frequent and often end with one male chasing another high over the tree tops and out of sight.     The appearance of a female generally results in a moment of fevered chaos as one or more males tries to seize the female.     Once successfully coupled, the pair flies off high into the nearby woodland to mate.

Spatterdock females oviposit (lay eggs) in emergent or aquatic vegetation at the water’s surface.       Females have been observed ovipositing in the stems of spatterdock (Nuphar sp.), pondweed (Potamogeton sp.), and the dead stalks of cattails (Typha spp.).    The eggs probably hatch within 30 days, but the nymph may take as long as 3–4 years to reach maturity.”

The naiads hatch and don’t stray far from their natal plant, stalking their prey as they climb around in the thicket of underwater stems.

The BugLady has heard that there might be a 12-Step Program for dragonfly enthusiasts (but -– why???).  An alternative to the Program might be a new camera lens or a pair of those nifty binoculars that allow you to focus on dragonflies that are only a few feet away.  Group therapy will be provided for dragonfly addicts at the Riveredge Nature Center annual Dragonfly Count (this year, combined with the Butterfly Count), which will be held on July 11, from 9:00 a.m. to 3:00 p.m.  Come for part or all of the day, and bring your own munchies, sunscreen, and plenty of water.  For more information or to register, contact Mary at mholleback@riveredge.us or 262-416-1224.  Pre-registration is required, as are face masks while checking in, while indoors and where social-distancing is difficult outdoors.  (A $5 donation per attendee is welcomed.)

Kate Redmond, The BugLady

Bug of the Week archives:
http://uwm.edu/field-station/category/bug-of-the-week/

Bug o’the Week – Gypsy moth

Howdy, BugFans,

The BugLady heard from BugFan Joanne recently, from out of state.  Her State Department of Agriculture was doing aerial spraying for gypsy moths, and Joanne was having a Silent Spring moment.  “Today it seems remarkably bug free around our yard,” she said, “and I am worried.”  Here’s a slightly-revised BOTW (some new words and pictures) from ten years ago in which the BugLady did a little sermonizing.

Nota bene – the opinions expressed below belong to the BugLady, who doesn’t have a single bit of vegetation that could be accused of being a horticultural planting.  Don’t beat up on the various wonderful organizations that archive BOTW.  Also, the BugLady does not like collateral damage.

Grab a snack – this is a long one.

We all know the Gypsy Moth story; it’s the poster child of Invasive Species.  Gypsy moths (Lymantria dispar) (Lymantria comes from a Latin word for “destroyer”) were imported from Europe to the Boston area in 1868 by French scientist Leopold Trouvelot.  M. Trouvelot planned to do a little genetic tinkering to develop a hybrid gypsy moth/silk moth caterpillar that was hardier than the native silkworms.  America’s wild silkworm moths, family Saturniidae, include the spectacular Luna, Cecropia, Polyphemus, and Promethea moths (https://uwm.edu/field-station/giant-silk-moths-family-saturnidae/) along with some lesser-known, smaller species.  Their cocoons are rarely unraveled for their silk.  Our silkworms are not related to the domestic silk moth (Bombyx mori) in the family Bombycidae, and they’re not related to gypsy moths (family Erebidae) either.

Anyway, some of his breeding stock (inevitably) escaped.  The first recorded outbreak was in 1889, and gypsy moths now occupy a wedge of the US from New England to the Carolinas to Minnesota (to see a nifty, animated map that only goes to 2007, check out (http://en.wikipedia.org/wiki/Gypsy_moth_in_the_United_States).  They are considered to occupy about 1/3 of the area they could potentially expand into, and in the past 150 years they have stripped gazillions of leaves from billions of trees in the territory they do occupy.  Gypsy moth caterpillars feed at night on some 500 kinds of plants, and they are considered a major pest of hardwood (deciduous) trees.  Adults are short-lived and do not feed.

Caterpillars are bristly (some people suffer skin irritations from contact), with two bulbous tufts of hairs in front, and two more aft.  Gypsy moth larvae get around pretty well – newly-hatched caterpillars use silk to balloon to greener pastures.  Caterpillars feed for six weeks, generally in the treetops.  The youngest (black) caterpillars chew holes in the middles of leaves, and when they are slightly older they eat the leaf from its edge toward its center.  “Teen-age” caterpillars – more colorful, with paired red and blue spots – climb down to the ground to take shelter during daylight hours, returning to the treetops at dusk (during a heavy infestation, they may feed during the day, too).  If/when they have defoliated a tree, they hike overland, en masse, to find another.

Males grow through five instars (an instar is the eating phase between two molting phases) and females have six instars before they look for a place to pupate (which may be on a tree, a porch, a stack of firewood, a travel trailer, etc.).  After pupating for two weeks, males emerge before the females so they are lined up when the females emerge, and the wild rumpus begins.  Adult females are flightless and are stuck wherever they pupated – they use pheromones to lure flying males to their perch, and then create an egg case on the same spot.

What’s all the fuss about?  It’s estimated that gypsy moths defoliate more than a million acres of forest a year – sometimes significantly more – and they consider trees on suburban lawns to be as tasty as those in the woods.  And then there’s the “Ick Factor.”  During a large infestation, roads, patio furniture, and outside walls are thick with the sights and sounds of caterpillars crawling and munching and of frass (caterpillar poop) raining down.

Tell us, BugLady, after 150 years of noshing, are there any trees left in the eastern US at all?  Why yes, Dearies, there are.  Ever driven the Mass Turnpike (which is close to gypsy moth Ground Zero)? There are huge forests of large trees, miles and miles of trees (though forest composition may have changed some).  For many trees, the defoliation is only a temporary nuisance.  A tree’s potential for recovery is based on what percent of its leaves are eaten, on its species and health, on the amount of soil moisture, and on whether this is defoliation number one, two, three, or more.  Most healthy trees will survive a couple of consecutive years of 50%-plus defoliations, re-foliating by mid-summer (although re-foliating saps their energy reserves).  Stressed or compromised trees may be killed by the next outbreak.

When caterpillar numbers are low (not every year is a BIG year), birds, shrews, mice (there’s a fascinating connection between levels of acorn production, mouse populations, and gypsy moth infestations), chipmunks, raccoons, wasps, ants, flies, fiery searcher beetles https://bugguide.net/node/view/535769, and weather (very cold winters and roller-coaster springs) are effective caterpillar controls.  In outbreak years, flocks of blackbirds and several bacteria, fungi, and viruses have joined the fray.

To these, we have added imported tachinid flies (of previous BOTW fame), whose maggots parasitize the caterpillars.  Tachinid flies that were imported to eat the imported gypsy moths, however, have acquired a taste for native caterpillars, especially caterpillars of our large silk moths, whose numbers have dipped.  We also wage chemical/biological warfare on them, in the form of the bacterial pesticide, Bacillus thuringiensis (Bt), and with chemical pesticides – contact poisons that affect a larva’s digestive tract (and that may damage humans, too).  In some parts of Britain, test areas were “flooded” with pheromones to overwhelm the male gypsy moths’ senses and keep them from finding females.

The $64,000 question is “Should something be done about gypsy moths?  The answer seems to depend on whether people see a lot of caterpillars on the landscape or only a few.  Eric R. Eaton and Kenn Kaufman, in the Field Guide to Insects of North America state that “Probably more damage has been done by the huge amounts of poisons sprayed on forests in ill-conceived attempts to control the moth.”  Most control methods are not specific to gypsy moth larvae (to repeat – MOST CONTROL METHODS ARE NOT SPECIFIC TO GYPSY MOTHS), and the blanket elimination of generations of larvae (collateral damage) affects the predators of the larvae and the predators’ predators and a whole lot of innocent bystanders.  The ripples move out, and maybe some ripples fetch up on the shores of insect-impoverished landscapes and barren July 4th Butterfly Counts (seems you can’t be a butterfly without being a caterpillar/larva first).  And yet people who go to municipal meetings to question community spray policies are accused of being “anti-tree.”

BugFan Naomi shared this personal experience: “I am out for the week in the Driftless area of Wisconsin, where my family has owned a piece of land for 40 years.  Our land is a lovely piece of oak savanna but there has been this horrible “bloom” of gypsy moth caterpillars.  The trunks of the trees are positively hairy with them, an alarming concentration that is hard to fathom.  Just when one could despair that all was lost, we noticed that they were dying on the trunks, head down.  They explode into a goo when touched.  This turns out to be the work of some fungus they have ingested that is killing them.  So although as youngsters they are doing some damage on the lower branches, they are meeting their demise before going to the next stage.  Now the trunks are covered with hairy ‘skeletons’ (what do you call the furry, leggy remains of a caterpillar?).”

“Empties,” Naomi, they’re called empties, and one of two agents is at work.  One is a Nucleopolyhedrovirus (NPV), a naturally occurring, gypsy-moth-specific virus which causes a “wilt disease” that leaves the critters hanging from tree bark (and which is now used by the US Forest Service under the name of “Gypchek”).  The other is a gypsy moth-specific fungus called Entomophaga maimaiga (EM).  According to the Midwest Biological Control News, EM, a native of Japan (which has its own gypsy moths), was released near Boston in 1910 in an attempt to control outbreaks. Subsequent tests failed to detect residual fungus in the environment, so the experiment was halted. In 1989, analyses of bunches of mysteriously-dead gypsy moth larvae in the Northeast revealed that their deaths had been caused by EM, but where it had been for 65 years is a mystery.

Trees themselves may have a solution.  Bill Bryson, in A Walk in the Woods, offers this story (whose “science” the BugLady verified with her plant guy).  Oak trees that are heavily infested with caterpillars emit a chemical (distress) signal that travels to trees downwind.  As a result, the downwind populations of trees produce higher levels of tannins, chemicals that make the leaves unpalatable.  To this the BugLady says “Wow!”  When the BugLady was taking science (and dinosaurs roamed the earth) a list of plant attributes did NOT include the ability to send/receive/process/react to this sort of external stimulus.

Kate Redmond, The BugLady

Bug of the Week archives:
http://uwm.edu/field-station/category/bug-of-the-week/

Bug o’the Week – Spectacular Summer Dragonflies

Howdy, BugFans,

 

This episode originally appeared in 2011 under the title of “Confusing Summer Dragonflies.”  They are confusing in that they all have dark patches on their wings – interspersed with white patches in mature males but not in juvenile males.  The word “pruinose” rears its head again, as the abdomens of males of today’s dragonflies develop some degree of “hoariness,” due to the production of waxy scales, as they age.

Represented by 103 species in North America, the Skimmer family (Libellulidae) contains our most common and conspicuous dragonflies – Pennants, Meadowhawks, Gliders, Corporals, Pondhawks, Whitefaces, Saddlebags, Skimmers and the like.  According to Sydney Dunkle in Dragonflies through Binoculars, they are colorful but not metallic, often have patterned wings, and their eyes contact each other at the top of their head.  Skimmers are often sexually dimorphic, with colorful males and not-so-colorful females.

 

A female Skimmer doesn’t have an ovipositor like females of other dragonfly groups so instead of “inserting” her eggs into the water, she jolts them from her abdomen by smacking its tip on the water’s surface above submerged vegetation.  Males generally “hover-guard” while their ladies are thus engaged, preventing them from being shanghaied by rival males.  Widow skimmers, Whitetails and Twelve-spots prefer shallow ponds and lakes, and very slow streams with lots of organic muck on the bottom.  Submerged aquatic plants are great, but they don’t care for floating duckweed leaves that coat the water.  They are effective predators of mosquitoes and other aerial insects.

 

Today we take to the air with three big dragonflies that belong to a group called the “King Skimmers” – the genus Libellula.  Four-spotted and Slaty Skimmers are also in the genus, and Chalk-fronted Corporals (Ladona julia) are sometimes included in the group.  Dunkle calls the King Skimmers “the quintessential dragonflies” – strong fliers, feisty, territorial, stout-bodied.  Compared to the damselflies, these are giants; a few damselflies could easily sit on each of their wings.  All have dark eyes; the males are pretty distinctive, but the females can be a bit confusing.

 

As with most dragonflies, the information sites on the internet are logarithmically outnumbered by the zillions of photography sites that feature the work of happy dragonfly stalkers, and there is a lot of dragonfly merchandise available on the web.

 

 

TWELVE-SPOTTED SKIMMERS (Libelula pulchella) are the largest of the three (pulchella means “little beauty” but their body is about 2” long and their wingspread is 3”).  Males, females and juveniles all have 12 dark spots on their wings, and mature males add white spots between the dark (a correspondent of the BugLady’s says they look like checkered flags).  They used to be called Ten-spotted Skimmers by people who were counting the light spots instead of the dark ones, but that name didn’t describe the female. The wing spots of female Twelve-spots are similar to those of female Common Whitetails, and they both also have dark abdomens, but if you can get one to sit still, you’ll see a “solid” light/yellow stripe” along each side of the Twelve-spot’s abdomen.

Female

The BugLady frequently sees them perched on last year’s weed stalks in her grassy field, far from the waterfront properties where they woo and win female Twelve-spots.  When they’re chilly, they face into the sun and raise their abdomens, to maximize exposure.

Juvenile male

Male

Males characteristically fly, stop and hover, and then chase off in a different direction, and when disturbed, they will often return to the same sentinel post.  They patrol a territory, chasing off dragonflies of all species and psyching out other Twelve-spot males by executing vertical loop-the-loops around them.  Some of the Atlantic Coast Twelve-spots migrate in fall.

 

COMMON WHITETAILS (Libellula (sometimes Plathemislydia) are the flashiest of the three.  They’re just under 2” long and a little chunky-looking, and the male’s spectacular pruinose, white abdomen (powder blue in younger males) contrasts with his large dark wing spots (just one on each mid-wing).  Females can be distinguished from female Twelve-spots by a white/light line along each side of the abdomen that is broken/zig-zag, not continuous, and the edges of her dark wing spots are more jagged, too.  Juvenile males’ bodies are marked like females, but as they age, the pruinosity covers the abdominal markings.

Dunkle says that adults are attracted to the dark of mud, where they often perch (of the three, they are most often found on the ground), and they often sun themselves on rocks.  They are most uncooperative, jumpy photographic subjects.  Males fiercely defend a territory about 12 yards long over open water and pond edges.  Dominant males display their bright tails; submissive males lower theirs.  Females lay their eggs in the shallows where there is a lot of submerged vegetation (the habitat their naiads prefer), and the naiads are tolerant of low dissolved oxygen in the water.  If she wants to lay eggs on his prime real estate (up to 1000 eggs in a sitting, repeated every other day), she must mate with the owner.  According to Legler in his wonderful Dragonflies of Wisconsin, a naiad that is ready to transform into an adult may crawl as far as 150’ from its watery home before emerging.

 

The exquisite WIDOW SKIMMER (Libellula luctuosa) is the BugLady’s favorite of the three.  Widows are so named because they oviposit without the protection of their mates (one source reports that luctuosa means sorrowful and compares their wing color to mourning crepe).  They perch down in the tall grasses and fly up unexpectedly as the BugLady explores, spotting her long before she spots them.

They’re just a bit bigger than Common Whitetails but, to the BugLady’s eye, they look sleeker.  In both sexes, the base of the wing is brown (in the Common Whitetail, the dark patch is toward the middle).  Males have big bluish-white spots next to the brown, fading to clear-ish patches at the wing tips and may have a blue tinge/pruinosity on the abdomen.  The center of the female’s abdomen is a black stripe, bordered on each side by broad, gold stripes that merge at the thorax like an inverted V.  Juveniles start out looking like females, and the juvenile male’s abdomen gradually changes color.

 

When there aren’t many Widows around, males each defend their own territories (up to 250 square yards), but the territories move daily.  Defense of their home turf can be a contact sport.  With overcrowding, a dominant male emerges and he gets all the ladies.  In dense populations, the male will guard his female as she lays eggs; if she gets raided by an intruder, he will discard his rival’s reproductive material and replace it with his own.

 

Besides the Legler and Dunkle books, the BugLady recommends Dragonflies of the North Woods by Kurt Mead, Dragonflies and Damselflies of the East, by Paulson, and the Stokes Beginner’s Guide to Dragonflies.

 

Kate Redmond, The BugLady

Bug of the Week archives:
http://uwm.edu/field-station/category/bug-of-the-week/