Tuesday, September 17, 2019

Life on a Spicebush

Life on a spicebush leaf -Tonya Smith
I borrowed these photographs from Tonya Smith MN who has recently become addicted to macro photography.  Recovery is seldom possible so I am using this blog as a warning to others who might be spared.  She found this on a spicebush leaf and sent it in to Bugguide on September 5th as a Bug Track.  On the 10th, she had this reply.
"This is a row of eggs inserted under the leaf epidermis. The little lid-like appendage at the top of each one suggests Heteroptera, and my first guess is Miridae (plant bugs), but I don't have any experience with their eggs, so it would be great if you could collect the leaf and see what pops out. Great photos!"… Charley Eiseman, 10 September, 2019 - 5:49am
Closeup with "lid-like appendage on top" - Tonya Smith
There are several lessons to be learned here.  First, there is a community of fellow "macrophiles" out there who are willing to give a helping hand, although some like me can be wrong at times.  Charley Eiseman, quoted above, is the guru and has helped me out several times and is generous with his expertise.  After years of assisting me in my gall addiction, he has ventured into life "in a leaf."

Leaf miner on Verbesina virginica - REK
While chasing chasing tiny critters on leaves I frequently see these scars.  They may occur on the upper or lower surface, sometimes on both.  I had always assumed that they were caused by something browsing the epithelium but it turns out to be something much more interesting. 
A leaf miner is any one of numerous species of insects in which the larval stage lives in, and eats, the leaf tissue of plants. The vast majority of leaf-mining insects are moths (Lepidoptera), sawflies (Symphyta, close relatives of wasps), and flies (Diptera), though some beetles also exhibit this behavior.  Wikipedia
Leaf miner tunnels with trails of frass - REK
Note that it says "lives in."  These tiny larvae mine in between the upper and lower surface epithelium, frequently leaving little tiny strings of dark frass (insect poop).  Eventually they emerge, leaving through a small exit hole which you may see under magnification.

If you want to pursue leaf miners beyond the Wikipedia reference, Charley has just published  Leafminers of North America.  It is 1857 pages long (plus a 54-page table of contents, 20-page glossary, and 68-page bibliography), illustrated with thousands of color photographs.  To prevent injury to the UPS delivery drivers it is only available as an ebook but it is a great reference.  "Abandon all hope, ye who enter there" for I have sampled the incredible deep dive into my copy and it is hard to emerge.

He and Noah Charney wrote Tracks & Sign of Insects and Other Invertebrates which is an indispensable book for those who wander through nature wondering "what made that?" be it a gall, egg case, pupae, exuviae or an engraving left by an insect. 

Sunday, September 15, 2019

Little Stinkpot

Saturday's field school for the Master Naturalist training class turned up a cool cold-blooded specimen in the creek, an eastern musk turtle, Sternotherus odoratus, the smallest Missouri turtle and one of the smallest on the planetOdoratus is Latin for "fragrant" and its alternate common name of stinkpot sounds ominous.  This is because of scent glands from the edge of its shell which can release a foul musky odor. possibly to deter predation.  Realizing that these were naturalists, it held its fire (or maybe he was just too young for his hormones to arrive.)

"Just call me spike."
Working with the WOLF School, the students almost always give a name to a turtle, snake or even a worm.  I tend to refer to specimens I pick up as "he," a trait that frequently gets me in trouble with my wife.  In this case I am justified as Wikipedia says that "males can usually be distinguished from females by their significantly longer tails and by the spike that protrudes at the end of the tail.

This is a very wise looking turtle, somewhat anthropomorphic but said with affection.  The MDC Discover Nature Field Guide described it this way.  "There are normally two thin, yellow stripes on each side of the head and neck. Small projections of the skin called barbels are present on the chin and throat."  To me it looks like it missed a few spots on its chin while shaving.  Technical note: even male turtles do not shave.

The MDC Field Guide describes its diet writing "A variety of small aquatic animals are eaten by this small reptile, including aquatic insects, earthworms, crayfish, fish eggs, minnows, tadpoles, algae, and dead animals."
"This species is most abundant in slow-current sections of rivers and larger streams of the Ozarks, the swamps, sloughs, and small ditches of the Bootheel, and in a few rivers in the northeastern part of the state. They can also be found in reservoirs. It favors shallow water but also basks on logs, rocks, or small, horizontal tree trunks"
You can't buy Master Naturalist fun like this!  Photos by Becky Swearingen.
For more details go to this Virginiaherpetologicalsociety.com link.

Wednesday, September 11, 2019

Velvet Ant Revisited

Some years ago I was out with some young naturalists.  All kids are naturalists if given a little freedom and encouragement.  They found this critter running rapidly through the cropped grass and weeds by our swimming hole.  The consensus among my young colleagues was "Wow, look at that ant!" and they were partially correct.  It is a velvet ant, an "ant that ain't," actually a solitary wasp of the family Mutillidae.

I chased this swift creature for several minutes before I was able to get it into a bug box.  Due to its formidable appearance, I was never tempted to touch it during the chase, a wise decision.

Male velvet ant - C. S. Lewallen - Entnemdept.ufl.edu
Velvet ants are characterized by their dense hair in vivid shades of red, orange or yellow.  The males have wings and usually have different coloration from the wingless females.  Bright colors in insects are frequently warnings of toxicity or the ability to hurt predators like us.  Other harmless insects may also have these colors, a form of mimicry.

Their other name is "cow-killer" which probably gives you a hint of their defense. The name derives from the female's stinger.  Although one species of velvet ant has a sting rated as a three on a one to four scale, many species' venom strength is less than a honey bee.  The Schmidt sting pain index was created over the years by entomologist, Justin Schmidt, prompting insects to sting him and then grading them on the severity of the pain in terms usually reserved for a wine connoisseur

Adults feed on nectar and water.  The male flies looking for females on the ground. They are parasitoids, rearing their young which slow feed on other species, eventually killing them.  Finally they emerge, the male flying off and the female crawling away as a warm and fuzzy "ant" - well maybe not so warm.
"Male mutillids fly in search of females; after mating, the female enters a host insect nest, typically a ground-nesting bee or wasp burrow, and deposits one egg near each larva or pupa. The mutillid larvae then develop as idiobiont ectoparasitoids, eventually killing their immobile larval/pupal hosts within a week or two." Wikipedia
Ant Petiole - UCIPM
One way wasps differ from ants is by their thicker pedicel ("wasp waist"), the connection between abdomen and thorax.  Ants have one or two petiole nodes between thorax and abdomen.  For identification of a velvet ant, just go by the color, don't bother picking it up to see this detail.

Monday, September 9, 2019

Pawpaw for WOLF

This week we had a record harvest of fruit on the pawpaw trees growing along the trails.  We ended up with 17 pounds, 4 times our average year.  Many of the biggest ones were hanging in clusters.  We go after them with a long pole with a hook on the end, pulling down all we see.  We have learned that when you think you have reached all of them on the tree, give it a good shaking and more unseen fruit is likely to come raining down on your head.

Pawpaws have a tight green skin, firm until they ripen, then soft, squishy and  full of the sweet odor of a over ripe banana.  Inside, there is a pale custard-like pulp with several brown seeds.  Fortunately those characteristics make some people dislike them which means more for us.  The pulp makes wonderful pawpaw pudding, the consistency of a moist cake.  It also can be used for pawpaw bread or served on top of ice cream.

The pawpaw tree (Asimina triloba) is much more important for wildlife.  Their fruits are popular with squirrels, raccoons, and bears.  In season we see bear scat filled with seeds, the pawpaw tree's method of transporting its offspring out of the neighborhood. 

Pawpaw flowers, fresh, dead and frost damaged - REK
Bud ready to flower
Pawpaws bloom early in spring and sudden freezes turn them into shriveled dark brown blobs, robbing them of the chance to make fruit.  Their survival trick is to spread out their flower bloom times.  We have noticed over the years that the flower blossoms develop and open up sequentially over 4-6 weeks in the spring.  On the same branch there may be shriveled frozen buds, tight buds both ready to open and fully opened blossoms, the whole spectrum on a single tree. 

Pawpaw also reproduce by suckers, roots extending out to establish trees nearby in an expanding community.  Left alone they could cover a large area but as a forest matures over years around them, their expansion is controlled.

Pawpaw flowers in full bloom - REK
Like other species producing dark brown to purple flowers, the pawpaw flower smells bad, somewhat like rotting flesh.  This attracts insects that normally seek out dead animals.*  Their flowers are pollinated in a hit and miss fashion by flies, beetles and other species.  In some limited attempts to grow pawpaw commercially, growers actually hang dead fish and other lures to attract these morbid pollinators to their trees.

Zebra swallowtail - Chris Barnhart
All of these insects are important to the pawpaw but one that totally depends on it is zebra swallowtail caterpillars, Protographium_marcellusThey can only eat pawpaw leaves.  If these trees disappeared, so would the butterflies.

Zebra swallowtail egg already perched on the first unfolding leaf of the year!  REK
Megan McCarthy CC
Several years ago I was out in the woods and checking a number of pawpaw trees.   I found a few leaf buds opening and then felt the sudden thrill of discovery.  There, on a tiny unfolding leaf, sat a glistening pale green egg of a zebra swallowtail.  A female zebra swallowtail very carefully lays an individual egg on the underside of a leaf.  It seems to know that its offspring don't play well together so it lays only one egg per leaf.  When the zebra caterpillar emerges, it eats the egg case for energy, and then may eat neighboring eggs if they are available.  Since the only likely species on a pawpaw are zebras, it doesn't pay to invest the energy in eggs that will not survive.  It is interesting to contemplate how this trait occurred.

*Further information on pawpaw odors is in this paper.
Previous pawpaw blogs have covered zebra swallowtail eggs, the  butterfly's premature delivery and the Asimina webworm moth that lives curled up in pawpaw leaves.

Friday, August 30, 2019

Rough Bulletgalls

Galls with a house fly, Musca domestica
I have been dissecting these rough bulletgalls which were clustered all over the branches of a small bur oak at Wonders of Wildlife.  Courtney Reece who teaches at the WOLF School had noticed wasps and flies swarming the tree and sent me the whole story.  She also researched it and came up with a diagnosis of rough bulletgalls.  These galls are produced by a rough bulletgall wasp, Disholcaspis quercusmamma.

She warned me that there was a large number of yellow jacket wasps on the tree.  The numbers were down by the time I arrived but the wasps were on their sugar high and paid no attention to me.  While they are notorious for attacking people threatening them by walking over the hole of their nests in the ground or running a mower over them, these didn't seem to be bothered by my camera a few inches away. 

So why all the insect traffic?  These galls exude a sugary juice that is an invitation to party to a number of sweet-loving insects.  According to Bugwood, "Rough bulletgall wasps produce a woody, generally rounded gall on bur oak, with a slight point. Very heavy infestations can occur that largely cover twigs, reducing growth rate of the tree. The galls also exude a honeydew-like sweet material that is attractive to bees and wasps and fosters growth of sooty molds."

Bulletgall wasp - Whitney Cranshaw - CSU
D. quercusmamma has an interesting life history. 

"Females emerge in late October and early November, after a hard frost. (A small circular hole in the gall indicates emergence.) Eggs apparently are laid in the terminal growth during the fall. winged and wingless forms are produced; males apparently are unknown.

Gall opened
In late spring, the developing insect stimulates a pocket of stem tissue to produce a large rounded gall, in which the young wasp develops. Galls are pale brown and soft in early stages, later darkening and hardening. Only a single wasp develops in each gall, although sometimes other insects (inquilines) also share the gall. The larva pupates within a small cell in the center of the gall, emerging in early fall. There is one generation per season." Bugwood Wiki

Three layers surround pupa case
Pupa, case and umbilical connection
The gall is firm and leathery, hard to cut open.  The outer layer is woody and tough, covering a thick middle layer the consistency of a dry apple that breaks off in chunks.  A thin third layer surrounds the pupa case leaving an open space around it.  The case its self connects to the inner layer of the gall with a knobby stem, somewhat like an umbilical cord which provided nutrition to the larva.

Syncophila sp. parasitoid wasp - Tom Murray
In attempting to raise the gall wasp, you can't just assume that what emerges is the cause of the gall.  Like Forest Gump's box of chocolates, the life and food web doesn't end there.  There are at least five Sycophila sp.  of parasitoid wasps that  live in D. quercusmamma larvae. Sometimes other insects (inquilines) also share the gall.
More on bulletgalls in general is at this Ohio State University site.
A sharp eyed WOLF Student examining the galls noticed a tiny 1/2" patch of eggs on a leaf.  We kept the leaf in the box to see what would emerge.  There were tiny 1mm black dots in the box 3 days later.  The best macroscopic photograph I could manage showed enough in profile to call it a "ladybug" (beetle actually) larva.

H. axyridis
It is most likely a European lady beetle, Harmonia axyridis.  It is now commonly found in gardens and fields, especially where humans influence the landscape.  This isn't a bad or invasive species although it does tend to out compete with some of our native species.

H. axyridis larva
H. axyridis pupa

Friday, August 16, 2019

Another Jumping Spider

I saw what initially looked like a small ant slowly scouting the surface of a patio table.  It was less than a quarter inch long (5mm) and skittish when I got too close.  I was able to get these pictures with my cell phone, a bit blurry when blown up but good enough to ID it on INaturalist as a Common Hentz Jumping Spider, Hentzia palmarum.

It has impressive front legs that resemble a crab spider.  When I got too near it jumped several inches over the table edge and dangled by a trailing strand of silk before climbing back up.  Jumping spiders don't build webs but also use their silk to create a burrow to hole up into.

H. palmarum - Large central eyes - "The better to measure the jump on you with"  - Wikipedia
H. palmarum  David Hill - Wikipedia
They hunt by relying on their large eyes in front as they stalk their prey (See last month's blog for a discussion on their binocular vision).  The long front legs holds their prey while they inject their venom.  The black and white striped structures in this photograph are their pedipalps or jaws.  The large pedipalps and dark color generally identify this as a male.  There is a good video of H. palmarum in action at this Youtube link.

Female H. palmarum - Brandon Woo

There is a dramatic difference in appearance between the male and female, making them look like separate species.  According to Bugguide "Females are hairier, paler in color, often marked with forward pointing triangles along the center of her abdomen."

Brandon Woo's specimen looks warm and cuddly compared to the males, unless spiders aren't your thing.

Monday, August 12, 2019

Milkweed Munchers

Barb was dumping plant debris into the compost pile when she noticed this bug crawling around in it.  Lifting up some of the old scraps revealed even more of them.  They measured 3/8" (10 mm) and required magnification for final identification as small milkweed bugs, SMB - Lygaeus kalmii.

Box elder Bug
On first glance it resembles a smaller version of the box elder bugs that swarm later in the year. They tend to migrate into the house, occasionally using their plant-sucking proboscis to puncture the skin, causing slight irritation.

The distinctive coloration of SMB made the identification relatively easy.  It has a bright orange incomplete "X" on the back and the upper black marking is somewhat heart shaped.  The anterior edge of the pronotum (the plate covering the first portion of the thorax) has two small black spots.  L. kalmii also has a small red spot on the back of the head extending forward, visible only with magnification.

When I think of milkweed, I associate it with the poster child of lepidoptera, the monarch butterfly.    SMB feeds on milkweed seeds as well as the nectar from other forbs.  They can also predate on small insects when other food sources are depleted.

The adults lay their eggs on milkweed in the spring and the larvae require milkweed to grow.  They absorb and store the milkweeds toxin glycosides which are harmless to them but serve as a defense against predators.  Actually at least four other insects feed on milkweed without ill effect from the toxic chemical.

Large milkweed bugs - Wikimedia
The large milkweed bug, Oncopeltus fasciatus is nearly twice the size and has a different pattern of the same colors.  Both the adult and larval forms feed on milkweed juice and seeds when available.  O. fasciatus is commonly used in science due to ease of rearing and ease of dissection, a trait that is probably not of significant survival value to the bug but is a boon  to science and education. 

Milkweed beetle-Wikimedia
The milkweed beetle, Tetraopes_tetrophthalmus likewise stores the toxins and advertises its distastefulness.  All the above species share the black and orange aposematic coloration, as does the monarch, warning potential predators that they are toxic. After the eggs are laid on stems at or just below surface, larvae bore into stems, overwinter in roots, and pupate in spring.  The adults appear in the early summer to repeat the cycle.

Our final contestant lacks aposematic coloration.  The milkweed stem weevil,  Rhyssomatus lineaticollis, can be quite destructive of rare and endangered milkweed species.

Milkweed stem weevil - Ken at Bugguides
"Adults initially feed on the apical leaves and then, after feeding, female weevils walk to lower parts of the stem and chew several sequential holes in the stem, creating a continuous scar. Females lay a single egg per hole and larvae complete development inside the stem while feeding on pith tissue."  bugguide.net
A mastication of caterpillars
We have previously written about the Milkweed Tussock Moth.  There are lists of special names for groups of animals such as a "murder of crows."   The "official" name for the group of caterpillars is "an army of caterpillars" but I like Kevin Furth's naming of a "mastication of caterpillars."  They are enough to make crow vomit as seen in this blog.

All insects that have milkweed in their diet at some part of their life cycle are poisonous to their predators because of the toxic cardiac glycosides contained in milkweed sap.  Brightly colored or not, don't eat them!

MN Members:
Got Milk-weed seeds?  MDC is collecting them for monarchs.  Store them in a plastic bag and we will get them to MDC at a later time.

Tuesday, August 6, 2019

Becky's Decorated Moth

Find the caterpillar on a zinnia flower head - Click to enlarge - BS
Becky Swearingen sent us this photograph to identify a caterpillar feeding on the composite flower head of her zinnias.  We couldn't even find it until we had closeup macro views.  After zooming in on the photograph above, watch her video here to see it in action.

Dressed up for a date with a flower - BS
This cool cat is a waved-lined emerald larva, Synchlora aerata, also known at the camouflaged looper.  It decorates its back with fragments of the flower heads it eats, (Aster, Rudbeckia, Liatris, Solidago, etc.) changing its appearance depending on the host plant.  This gives more meaning to "You are what you eat."
The fresh fragments blend in with the flower head, concealing the caterpillar until it moves.

Loopers or inch worms are members of the Geometridae family, from the Greek meaning "measure the earth."  The earth may be a slight exageration but they certainly can pace off a flower head.  They come equipped with only two or three pair of legs on the back end instead of the usual five pair of other lepidoptera larvae.  They use the hooks on the front legs to hang on while bringing up their rear to clasp before stretching forward again.

Decorated cocoon - Wikipedia ES
When the larva molts, the decorations remain on the old skin (exuvia) and gives it a chance to develop a whole new look, as by then its decorations have dried and turned dull.  Likewise, when it forms its cocoon, the decorations remain, giving it some further camouflage.

Wavy-lined emerald moth - Wikipedia
The larva decorations are a unique trait among moth caterpillars, found only on
S. aerata and S. frondaria found along the east coast.  The technique is different from the bagworm moths, Psychidae, that spin their case of silk and leaf fragments, carrying it along like a light weight motor home.  There are a few other species of insects which decorate their backs, the subject of a future blog. 
Thanks to Phil Koenig from BAMONA for information on the genus Synchlora.  Also to Dr.  Becky Swearingen for the inspiration, the caterpillars and the photographs.