Tuesday, August 23, 2016

Cloudless Sulfur Migration

Cloudless Sulfur - Bob Moul
In recent weeks we have been seeing a sulfur butterfly, larger than the usual varieties of small yellow sulfur butterflies flitting around our plantings.  This is the Cloudless Sulfur, a visitor that migrates to Missouri and neighboring states from the south in late summer.

When it comes to insect migration, we think of the dramatic Monarch migration, one of the wonders of nature.  Dragonflies like the Green Darner can sometimes be seen migrating in dramatic numbers.  There are however a lot of other smaller scale migrations that are so subtle they are often overlooked.  Most migrations of insects are noted by the appearance of seasonal increases in a regional population.

The Cloudless breed continuously in the tropics and twice a year in the southern US.  Some migrate north as far as Canada in middle summer where they find the warmth they need.  They feed on woody and herbaceous legumes which span from alfalfa and soybeans to the leaves of black locust.  Whether they are driven to migrate north by host plant availability or by temperature gradient is known only by the butterflies and they aren't talking.

The migration of Monarchs tends to occur at higher altitudes while the Cloudless travel in a zone from within 10 feet of ground level.  When they encounter a house or some other obstacle they tend to fly over it rather than temporarily change direction.* 

Cloudless survive the winter as adults and they don't tolerate cold.  In the fall, large numbers move south in response to cooling temperatures.  Those that chose not to go or take off too late will mostly perish.

The Cloudless sulfur, Phoebis sennae, looks superficially like other sulfur butterflies in its usual wing folded position.  The underside of the wings is between a yellow to pale green color with two small silver spots and a black rim on the hind wing which defy the naked eye when they are resting.

Dogface Sulfur - REK
Clouded Sulfur - Wikimedia

The upper wing surface is easier to identify but virtually impossible to photograph without capturing the insect.  The above chilled and released Southern Dogface shows its namesake and the Clouded Sulfur has "clouds" on the dorsal wing edges.  The Cloudless shows the clouds are gone.
 Cloudless Sulfur - ColtonEnto
The caterpillars are usually light green with a yellow stripe on the sides.  If they feed on a host plant's yellow flowers they are yellow with transverse black bands in later instars.

  Terry Schiff CC
  Sue Carnahan CC

Many other lepidoptera migrate including the Red Admiral, Common Buckeye, American Lady and the colorful Alianthus Webworm Moth.

* More details of Cloudless Sulfurs and their migration is at this University of Florida Entomology site.

Friday, August 19, 2016

Dog Bane

Silvery Checkerspot on early dogbane blossoms - REK
There are scattered patches of dogbane in our grassland, a species that most true farmers would consider a weed and try to kill but we save it for fiber.  Its scientific name is Apocynum cannabinum, the Apocynum meaning "poisonous to dogs," hence the bane of dogs.  It can also be toxic to cattle so we hay around the patches.

Milky latex
Its reddish stems ooze a white milky latex which can cause skin blisters. It is described as bitter tasting (there is always someone to try tasting) and contains cardiotoxic glycosides, the same family of chemicals as digitalis.  The roots had been used therapeutically in the past to treat heart failure.  With its bad taste, only a desperate horse or cow would continue eating it, but 15-30 grams of dried leaves reportedly will kill one.

Dogbane grows freely in fields and open areas, prefers moisture but is thriving on our upper hayfield.  The "cannabinum" might stir excitement in a lawman's heart but it comes from Cannabis as a fiber plant like hemp, and fiber is one reason why we protect it, but more on that later.

Spittlebug home - REK
There are a lot of insect associations with dogbane which add diversity to our otherwise boring fescue and Johnsongrass fields.  In spite of its toxicity, spittle bugs seem to love dogbane.

During the early summer most of the dark red stems have a little bit of drool concealing a tiny green bug, butt up in the air, blowing froth of dilute digested xylem out its rectum.  If you set aside the yuck factor and wipe away the bubbles, the little guys are actually cute!  These are the nymphs of froghoppers, little athletes capable of hopping 2 feet in the air.  They are well worth the blog focused on them alone.

Spittlebug exposed - REK

The broad head of flowers attracts a wide variety of pollinators including bees, flower flies, wasps, butterflies and moths.  The USDA/ NRCS ranks its value to pollinators as "very high."  Pennsylvania leatherwings (Chauliognathus pensylvanicus) are attracted to their pollen and their larvae attack many other insects.  Tachinid flies visit the flowers and lay their eggs on stinkbugs, Japanese beetles and other pests where their larvae grow up eating inside them until they die or at least don't reproduce.  Birds even use the fibrous fluff of the seeds for nesting material.

Milkweed is in the dogbane family (Apocynaceae), and a variety of "milkweed" insects visit ogbane as well.  Small milkweed bugs (Lygaeus kalmii) are attracted to them.  Dogbane is a host plant for several caterpillars including our beloved snowberry clearwing moths that mimic hummingbirds, nectaring without touching down.  Monarchs nectar on the flowers but their caterpillars can't survive by feeding on the plant.
Dogbane Beetle
I have left out one of the best for last, the dogbane beetle.  This gem literally changes color depending on the angle of the light, its metallic green sheen blending into gold and all shades in between.  According to Illinois State Museum:
"Chrysochus auratus iridescence "changes color because of stacks of tiny slanting plates, under which is a pigment.  Some light rays reflect from the surface of the plates, and other light rays reflect from the pigment underneath. At different angles, the light reflects at different speeds, causing interference and resulting in our seeing different colors that shine."
The eggs are laid in the soil or on the plant and the larvae tunnel in the soil to feed on dogbane or milkweed roots.  The adults are able to defend themselves by giving off a foul odor like many other beetles.  The best approach to them is to photograph them and enjoy them at a distance.

Colors we can't reproduce -  Nature Web
Dogbane cordage - REK
Ah yes, the fiber!  Hemp dogbane has been used for cordage by Native Americans for at least several thousand years.  The individual fibers that are found under the dry bark in the fall are stronger than cotton of the same size and found multiple uses from bowstrings to sandal soles.  Primitive skills instructors demonstrate the process at the Nature Center each year and you can learn to make your own cordage at this site.  We will be harvesting the dogbane this fall for the Wonders of Wildlife classes.

Wednesday, August 17, 2016

Thread-waist Wasp

Thread-waist wasp - Eremnophila aureonotata - REK
Silver-white shoulder patches
I watched this dainty insect flying slowly around at knee height for some time.  Finally it got tired of looking around and landed on the deck to rest. The long thin stalked abdomen put it in the Sphecidae family of Thread-waist wasps.  The silver-white patches on the side of the thorax is diagnostic of the genus Eremnophilia. and Eremnophila aureonotata is the only species north of Mexico.

Satellite fly - Patrick Coin
This species is commonly found in old fields near woodlands.  Adults feed on nectar while the larvae are fed moth and skipper caterpillars.  The female digs a burrow, places an egg in it and delivers a large caterpillar, a long term provision.  Some satellite flies commonly follow them, sneaking in to lay their eggs on the caterpillar.

Capturing a Notodontidae Moth caterpillar - Benny Mazur CC
I was fortunate this specimen landed on our deck for pictures.  Many of the online photographs are of mating couples on large flower heads such as Queen Anne's Lace, both slowing them down and getting them at camera height.  Rather than nibbling on her ear, the male grasps the female's neck with his mandibles and hangs on.

"This won't hurt much" - Grasping the female's neck -  Tam Stewart

Monday, August 15, 2016

Fuzzy Orange Galls

Callirhytis furva - R. Curtis
I found a few of these galls on a bur oak leaf.  A photograph online identified them as Spiny Oak galls and said they were caused by a Cynipid wasp, Acraspis prinoides,but nothing else was available on itAnother white oak leaf gall that might be confused with it is produced by Callirhytis furva, but this one is more hairy than spiky.

 Acraspis erinacei - Charley Eiseman
I would have described them as hedgehog galls so on a whim I searched that name and hit the jackpot.  Charley Eiseman, who has literally written the book on galls and other signs* as usual had  described my gall on Bugguide.   He identified the Hedgehog Gall Wasp as Acraspis erinacei and even had a photograph of the wasp.

The life cycle is a bit complicated.  The process begins when a fertilized female lays eggs on an oak leaf.  The hatchlings cause some damage and the leaf responds by creating the gall around them. The gall contains three to five larval cells, each holding a female that will emerge in the fall and lay eggs on leaf buds without mating.  After being exposed all winter, the larvae stimulate other galls, and adult males and females will emerge to mate and start the cycle over again.

Tracks and Signs of Insects and Other Invertebrates: A Guide to North American Species

Saturday, August 13, 2016

Red-spotted Purple

RSP - Belle
My 10 year old naturalist friend Belle sent me this photograph of a Red-spotted Purple (RSP) butterfly that reminded me of a past exploration into the caterpillars.  The RSP, Limenitis arthemis astyanax, is a forest butterfly that is well adapted to suburban areas with trees.  In flight it resembles Pipevine and Spicebush Swallowtail butterflies, a protective coloration called Batesian mimicry as a bird having tasted one of those toxic species is likely to leave the RSP alone.

Viceroy - Wikipedia
The RSP has an unusual trait of occasionally mating with the closely related Viceroy butterfly Limenitis archippus, usually in the lab but occasionally in the wild.  One definition of a species is their ability to breed so once again the definition of species is challenging.
RSP or Viceroy? - REK
Since the two species are close enough that they occasionally interbreed, it probably should not be a surprise us that their larvae can look similar.   They are the only bird dropping mimic caterpillars that have horns. The RSP is less spiny than the Viceroy.  I photographed the caterpillar above from many angles and yet we were never able to decide which species it was.  Only the mother knows for sure.

Southern Viceroy - Mark Fox
RSP - Carmen Champagne CC

Bird dropping mimic with horns - REK

The RSP rarely feeds on nectar from flowers, preferring fermenting fruit that is "spoiling" for us but tasty for it, tree sap and even animal dung.  They also will drink from moist gravel and mud puddles, acquiring the minerals they need for reproduction.

Thursday, August 11, 2016

Ganoderma On Our Roots

I generally like to see various fungi on the ground but this is not one of them, especially when it is in our front yard.  We had a large native thorn-less honeylocust tree when we moved into our new house in 1973.  Over the years it has provided shade and served as a perch for many different birds.  Now these are appearing on the exposed roots.

Mark Bower confirmed that this is Ganoderma sessile, a parasitic fungus on hardwoods.  Species names get dicey as they frequently change or get reassigned by DNA.  As some have suggested, naming a new species is frequently making a species hypothesis.  In this case a related species Ganoderma curtisii looks somewhat like it.

Ganoderma fungi are white-rot saprophytes living on dead organic material in the soil.  They produce enzymes that digest lignin and cellulose that provide the structural strength of wood.  When it encounters cut or damaged roots it can parasitize the living tree, its hyphae spreading through the roots.  When it gains a sufficient spread it is ready to reproduce, creating its "flower," the mushroom that will produce spores, its method of spreading to other areas.

Our tree has been struggling in its urban setting for years  It was growing on a thin layer of soil before we came, its roots extending well beyond the diameter of the crown.  First the street and then our house and driveway construction constrained the root expansion.  Next a sweetgum was planted to the south that slowly encroached on its sun.  It grew anyway, loyally providing afternoon shade to the house.

Ganoderma - Mole's eye view
The thin layer of added topsoil supported a lawn but provided no depth for growth of the feeder roots.  They reached the surface 20 years ago where they were occasionally scarred by lawnmowers.  This likely provided the entrance wounds for Ganoderma to attack the roots.

Shallow soil, uprooted trees
In recent years the tree started to lose branches.  Ganoderma will also spread into the structural roots that hold the tree upright.  Our locust tree is plagued with rocks and shallow, poorly drained clay soil that prevents deep root penetration any way, increasing the risk of uprooting in a storm.  Now our arborist, Chris, has delivered the "last rites."

The tree shaded us for over 40 years, reducing air conditioning bills and providing a refuge for squirrels.  Now with the tree gone, Ganoderma will continue its role of saprophyte, converting the remaining roots into soil nutrients to feed the tree we will be planting soon.

Tuesday, August 9, 2016

Redbud Mummies

Hiking a trail at Valley Water Mill Park I came across a small redbud tree with two branches covered with the cases above, over 200 total.  They were fastened on dead and green leaves as well as on the stems.  Most had a hole where a previous occupant had exited but some were still intact.  It was obvious that what ever these had been they were quite gregarious.

Campoplegine - silk cocoon underneath

I sent photographs to Dr. Scott Shaw.  He has written extensively on parasitoid wasps and he quickly responded that it looked like a "campoplegine ichneumonid. That would be the case if you can see the parasitoid silk cocoon underneath. Rogadine braconids cause a complete mummy of the caterpillar (no silk cocoon visible)."  A side view confirmed that suspicion.

Identifying a host caterpillar was a vexing problem.  After several dead ends I searched for "gregarious caterpillars redbud" and eventually came up with four suspects, Redhumped caterpillar-Schizura concinna, White Flannel Moth-Norape ovina, Io moth-Automeris io and Yellownecked caterpillars-Datana ministra.  I started from the top and found this Redhumped caterpillar Bugguide link, a photograph with parasitized specimens identical to mine.
Redhumped cats - Tom Murray CC

RH Moth - Tom Murray CC
Redhumped caterpillars (RH) are colorful and actually pretty, that is if they aren't skeletonizing your redbud leaves in mass.  They feast on a wide variety of woody plants and when they gang up on a leaf they are easy pickings for a parasitoid wasp depositing one egg per customer.  They will become a rather nondescript moth which has the cute habit of resting with its butt up in the air.

First instars - Edna Woodward
I was comparing the color and size of the RH cats and realized that these were parasitized at an early age.  The leaves hadn't been severely damaged and they were probably in the first instar when the wasp found them.  The literature suggests that a wasp can lay 100 eggs so this must have been a super fertile female or had a friend.

H. fugitivus - UC-IPM
Searching for parasitoids on Redhumps I came across this UC IPM publication listing two parasitic wasps attacking them, Hyposoter fugitivus, and Cotesia Schizurae.  This photograph of H. fugitivus from UC-IPM looks like a perfect fit.  I am waiting for confirmation.

I took several leaves home for study and after photographing them under the microscope I stored those without holes in separate containers. Two days later we announced the arrival of a bouncing baby wasp.  I watched it crawl around in its clear plastic box until I had to freeze it to photograph without it flying away.  Considering that over a hundred of its siblings had already emerged, I don't think this disrupted the cycle of nature.

Hyposoter lifecycle- UC-IPM
Life began for these wasps when their mother laid an egg in each of the small caterpillars.  As the larva emerges and starts to eat, the caterpillar continues to grow.  By the third or fourth instar it dies as the larva emerges and spins a cocoon to form a pupa.  This includes the flattened silk attachment to the leaf, tight enough that when I was pealing it away from the cocoon case it frequently brought some leaf with it.

When the male emerges, it will likely hang around to mate with emerging females, a steamy meeting described in this 1967 paper with the unromantic title of Sexual Behavior In Hyposoter fugitivus Hymenoptera Ichneumonidae.  The male touched the female's antennae, wiggling his alternating sides.  Then he started "vigorous wing fluttering" and.....we you know the rest and this is a family blog. 

A pair of these H. fugitivus and a few representative cocoon cases are in the mail, sealed in alcohol on their way for conformation and will become voucher specimens in the University of Wyoming Insect Museum, a long trip for a little wasp.

Special thanks to Dr. Scott Shaw for patiently sharing his knowledge this last week.  He is Professor of Entomology at the University of Wyoming, Insect Museum Curator and the author of Planet of the Bugs.