Friday, October 30, 2015

Rotten Log Project

Velvety bark beetle - REK
Ventral view of the velvety bark beetle
We have been collecting specimens for a rotten log project, creating a worksheet of examples for teachers.  I came up with the two specimens below and struck out on my attempts to identify them beyond being in the Polyphagia suborder.   I sent this beetle photo to Bugguide.net and got a response within 10 minutes from Invertebrate Dude, one of many contributors who patrol the pages, helping to identify specimens.

This is the Velvety Bark Beetle, Penthe pimelia, a rather insulting name as pimelia means fatty.  It is a member of the Tetratomidae family of polypore fungus beetles.  They are usually found under the bark of fungus infested rotting logs where they eat the fruiting bodies of fungi.



The other beetle was more more formidable, equipped with jaws that meant business.  It was rapidly identified as a False Mealworm Beetle (Alobates pensylvanica)* by Blaine Mathison.  The name false mealworm suggests a short future for some of the larvae which are raised for fish food in some aquariums.  It is a darkling beetle, long and larger, its elytra shinning and dotted with small punctures.  It is found under the bark of decaying logs where both the adults and larvae are predators of other rotting log insects.

* "pensylvanica" is not a typo.  Latin avoided double consonants although some sources chose to use pennsylvanica anyway.

If you are looking for help in identifying or understanding insects, consider joining Bugguide.net.  It is free although they would not turn away your financial support.

Wednesday, October 28, 2015

Life on a Maypop


Maypop fruit - REK
On a WOLF school field trip to Wilson's Creek Battlefield, a student gave me a tiny caterpillar to identify later. After we passed a set of passionflower vines entangled in shrubs, I put a maypop fruit in my bag. When I returned home I found the caterpillar had escaped and was hanging on the fruit. Under magnification the white spots glistened like silver. Short of time, I sent it off to Kevin Firth who identified it as Euptoieta claudia, the variegated fritillary.

Purple passionflower- REK
Just by chance the captive caterpillar had found itself in my bag with one of its several host plants.  It is only fitting that the beautiful caterpillar has an equally beautiful host plant, purple passionflower, Passiflora incarnata.  Also called maypop, the flowers are long gone, replaced by the fruit whose popping sound when you step on them is the source of this common name.


We are feeding the caterpillar leaves of yellow passionflower, Passiflora lutea, until we can return it to its "owner."  Hopefully the supply of leaves will hold out until it pupates.  It will wander off its leaves and find a spot to hang on, spinning a silk thread and then enclose (form its chrysalis).


Dorsal view - Bob Moul
Chrysalis - Carla Kishinam-CC

This spectacular caterpillar produces an even more beautiful chrysalis, glistening white with black and orange bumps.  The wings are under the chrysalis covering and yet seem to be ready to fly away at any second. Once it emerges, it overwinters as an adult.
Variegated fritillary - Bob Moul
 Addendum:
A week later our caterpillar formed its chrysalis. When we started to move it to safety 8 hours later the chrysalis started a continual wiggling.  The interesting part is when I shined a small flashlight directly on it, the wiggle abruptly stopped and didn't start again. Now 6 days later I put it in the sun and it started dancing again for this video.

Monday, October 26, 2015

Woolly Bears of Winter

<h5><big>Isabella Tiger Moth Caterpillar <BR></big><em>Pyrrharctia isabella #8129</h5></em>
Woolly Bear headed uphill - Bob Moul

Woolly bear playing defense
What could be more warm and fuzzy than finding a woolly bear caterpillar?  When I pick one up it will usually roll up into a tight defensive ball and lay still until it decides I am not going to eat it.  Then it straightens out and starts back on its journey to an unknown destination.  It is hard to know which end has the head until it starts moving again.  It doesn't seem to have a reverse gear.

While having a warm and fuzzy image, this caterpillar phase of the Isabella Tiger Moth, (Pyrrharctia isabella), is built for winter.  On a WOLF School march through Wilson's Creek Battlefield, the were a lot of bears on the trail, out searching for the perfect patch of duff for a winter home.

Adult Isabella Tiger Moth - Bob Moul
P. isabella pupa - Britannica.com
The caterpillar will undergo six molts (instars) before forming a cocoon and emerging as an adult moth.  It has only a few days to meet and mate before dying.  One or two generations each year go through their life cycle in a few months but the last generation overwinters as a caterpillar.  Its body produces the cryoprotectant chemical glycerol (antifreeze), letting it survive even after being frozen solid.  In the spring it will crawl out of hiding, eat a variety of plants for a few days and then pupate, forming a cocoon from which the moth will emerge.

Head - Wikimedia
A woolly bear has another challenge when it lives in the Arctic.  Due to the short growing season, food is available for only brief periods.  Each instar may have to face the winter before molting into the next instar.  Reaching adulthood may take several years. The record is an amazing 14 years!

The Weather.gov describes how the woolly bear got its reputation for weather forecasting.  Folklore says that the wider the orange band, the warmer the winter.  It turns out that the caterpillar does indicate the length of the winter, but the previous winter.  The longer the previous growing season, the wider the black bands.  A mild winter lets it get out and start eating early, giving the caterpillar a head start that year and a longer time to feed.

Thursday, October 22, 2015

Purple Ground Beetle

I found this purple ground beetle, Dicaelus purpuratus, running on the gravel of our driveway at Bull Mills.  They are a Great Plains species found between Illinois and Arizona inhabiting fields and deciduous forests.  Considered infrequent but not rare, they are valued by beetle collectors.

Powerful snail-crushing jaws
This is a predacious ground beetle which specializes in snails.  Many beetles eat snails by reaching in the opening to pull out the innards but this beetle comes equipped with mandibles powerful enough to crush the shells.  Their larvae live under logs or in the duff and also consume snails.

Members of the Dicaelus genus are felt by many to be the most beautiful beetles.  It is interesting to see the color variations between copper, purple, black and green as illustrated in Bugguide.  The color changes partly with the direction of the light beam and I had trouble capturing the color I was seeing with my camera.

Beetle belly with a mite attached to its right hind femur
Many beetle species carry mites on their body, either to their benefit in a symbiotic relationship as in carrion beetles, or as parasites.  They are common on ground beetles although to my knowledge we don't know exact association in D. purpuratus, but there is one seen clinging to the right rear femur above.

Their elytra are hardened forewings, covering hind wings that are no longer functional for flight.  They escape danger by expelling a defensive chemical out their anus, a trait shared with their larvae.  It is described as smoke-like or dark colored liquid with formic acid which would burn a predator.  I can attest to the odor as this specimen left a large amount in my specimen box which I had to throw away.
  
This beetle was shown to be an early example of the converse Bergmann principle.  Back in 1949 this paper in Physiological Zoology showed that Dicaelus purpuratus specimens are larger as you head south. This gets a little deep for us laymen but either bear with me or bail out now.
"According to Bergmann's rule, body size increases with latitude, a temperature effect. According to the converse Bergmann rule, body size decreases with latitude, a season length effect."  oxfordjournals.org
The common application of the better known Bergmann's rule is that mammals tend to be larger in Northern climes (think grizzly and polar bears) where increased body size and fat reduce their relative surface area to weight ratio, helping them maintain body temperature to survive harsh winters.

The newer (to me) converse Bergmann's rule is seen in some arthropods where the species are larger in their southern range.  This is frequently attributed to the longer growing season which means more resources and time to consume them.  And that is where our purple ground beetle comes in.  They are larger in southern states than they are in Canada.

Congratulations, you finished!

Monday, October 19, 2015

The Hand of Man - Part II


The previous hand of man posting discussed how human activity has changed the Ozarks waters through the introduction of the zebra mussel, and its effects on our lakes and streams.  The other part of the picture above was sent to me as a challenge to identify it.


Chris Barnhart had sent me this picture from Bull Shoals.  This had been underwater until the lake level had dropped, leaving several of these high and dry.  The twig indenting the side showed that it was flexible.  It resembled a spotted salamander egg mass but wasn't transparent and there were no eggs to be seen.  I finally gave up and he identified it as the magnificent bryozoa,  Pectinatella magnifica.  I was somewhat relieved to discover that no less than scientists at the Virginia Institute of Marine Science were equally puzzled when first faced with a similar glob.  Here is their description.
"The object is about 4 feet in diameter. It has moved about 6 feet down the shoreline in the last 24 hours. It 'jiggles' when the waves in the lake hit it… when we prod it, it seems to be spongy feeling… The texture appears to be that of a rock with algae spots on it -- it is brown and yellow, with a pattern of some type."  Sciencedaily.com
Bryozoans are single celled microscopic aquatic invertebrates that live in colonies.  These colonies can form round jelly-like masses or even form irregular colonies resembling moss (bryozoa means "moss animal").  P. magnifica  forms round masses, sometimes up to six feet in diameter.  Missouri Department of Conservation describes the animals like this.
Click to enlarge - Lander.edu
"Each tiny individual bryozoan (zooid) is attached to a surface at its base. Its body has an outer sleevelike structure (cystid) and a mass of organs (polypide) that moves within it. An opening at the top of the cystid permits the polypide to slide outward toward the water, exposing a headlike structure (lophophore) crowned with tentacles, which filter food from water. At the slightest disturbance, the polypide and tentacles retract instantly."
A community of rosettes - CB
This animal is a basic as it gets.  They are found in the fossil record 500 million years ago, unchanged from today's structure.  Immersed in water, they absorb algae, surviving without a respiratory, circulatory or excretory system.  They cluster together, 12-18 zooids (animals) forming each rosette within the jelly-like mass which is 99% water.  The rosettes form a community in their jelly-like blob which usually is attached to a structure but can be free floating.  Although they seem to be entirely passive, one study showed that small colonies could move by coordinated pulses of the individual animals.  Imagine a tiny rowing team of single celled animals with no nervous system!


Now the hand of man throws the community a curve.   For millions of years they have been living in bodies of water that may slowly rise and fall.  Now they are faced with sudden changes in the water level as man-made dams contain and then suddenly release water, leaving them suspended in the air.  They must be looking at each other in their rosettes, scratching their head-like lophophores with their tentacles, asking why man has done this to them.

"Hey guys, what's going on?" - CB

Saturday, October 17, 2015

A Deer Odyssey

Photo of a white-tailed deer buck sniffing the air.
What is he thinking?  Where will he go? - MDC Noppadol Paothong
I received this story from Dave Shanholzer, the travels of a single buck wearing a radio collar in Pennsylvania.  What is fascinating is the extent of its travels on a single day, twice in its life.  Each of us can only speculate on its purpose, and I won't spoil it for you.  Just read The Life and Times of Buck 8917.

Thursday, October 15, 2015

The Hand of Man


The Good, the Bad and the Ugly
On a recent trip to Bull Shoals, Chris and Deb Barnhart took photographs which show rather dramatically how the hand of man has affected our Ozark waters.  The picture above demonstrates two of the effects that Europeans' arrival in the Western Hemisphere has had on the White River.  One is a dense collection of zebra mussels.

The threat of this invasive species is well known but somewhat distant in our daily lives.  They reproduce prolifically, coating rocks and gravel bottoms as well as water structures, blocking water intake pipes.  Their razor shells turn shorelines into no wade zones.  They out compete native mussel species and steal the food supply from fish at the bottom of the food chain.

Zebra bluff - click to enlarge
The threat comes home when it happens here.  Bull Shoals has a dense population of zebras, coating the bluffs exposed when the water level went down over 10 feet this year.  They prefer hard substrates such as rock and even the shells of native mussels, impairing their movement.  The varying density of mussels on the bluff may represent the variation of rate the lake levels decreased.

Once again, the question of are they good or bad is answered "it depends."  With all their faults, there have been some benefits.  Each mussel filters a liter of water daily, removing plankton, algae and cyanobacteria from the water, a benefit in polluted waters like Lake Erie.  This improves water clarity, allowing sunlight to penetrate deeper.  Their feces falls to the floor, increasing the biomass, available to bottom feeders.  In one lake the yellow perch catch has increased 5-fold.


While no one is proposing importing them to unspoiled lakes, there is some benefit and reason for hope in this.  Zebra mussels are not going to disappear, but nature has a way of compensating for change, restoring some sort of balance over the years.  Lake floor invertebrates and fish reap the benefits of their poop (hey, it has to go somewhere!)  Studies on Lake Champlain have shown that twice the number of invertebrates lived in areas with zebra mussels.

After the zebra mussel population peaks, it frequently drops off some and in one case they weren't found later.  While this is too much to hope for and results will vary by climate and lake, it isn't the end of lake as we know it.

Now to the center of the photograph at the top, this was an unknown posed to me by Chris, a challenge I totally failed.  If it puzzles you too, tune in to the next blog.  Hint: It started out underwater and was exposed by falling lake levels.

Wednesday, October 14, 2015

Lacewing Eggs

Green lacewing larvae, a.k.a. aphid lion - REK
Barb's "tiny something"
This story began with a chance finding of a tiny "something." Barb was working with Lisa Bakerink salvaging swamp milkweed along South Creek before  the concrete was removed to improve storm water drainage. They were joined by Cody Stice from the Department of Public Works who came out on his own time to help. He spotted some tiny threads on the milkweed leaves and Barb brought a leaf fragment home for me to see.  I required a magnifier to see the specimen that was bent into a curve from the ride home but she said they were all were originally sticking straight 90 degrees off the edge, horizontal to the ground.  After a few wrong guesses I sent the picture to Chris Barnhart who identified it as a lacewing egg.

Green Lacewing species - Jon Rapp
Green lacewings (Chrysopa sp.) are beautiful and delicate creatures that are the gardeners favorite.  They and their larvae are frequently predators of garden pests such as small caterpillars, mealybugs, psyllids, thrips, mites, whiteflies, and aphids.

Lacewing Eggs - John Meyer
Chrysoperia pupa - nbair.resv
The female produces single eggs, each on a silk strand off a leaf edge which presumably reduces predation.  In a few days a larva emerges, eating everything it finds including any unfortunate siblings.  It will munch its way through three progressively larger instar stages before pupating in a loose silk cocoon.  Adults overwinter in leaf litter.

Aphid lion contemplating dinner - REK
The larvae would probably not be considered beautiful by even their mothers.  Also known as aphid lions, they resemble a prehistoric alligator with a bad haircut and any student would guess they are predators based on their fierce pointed jaws.  They grab their prey and inject a paralyzing venom before sucking out their juices, leaving behind the empty skin as they grab the next victim.  I filmed this video to document their appetite for aphids.  Three rapid sequence photographs below show an aphid going from happy to sucked dry.

Grabbing a quick bite
First taste of a fat morsel.......
..... now shriveled down to nothing.
Many companies offer lacewing larvae in bulk to populate your garden as a treatment for aphids.  However they will eat anything they get in their pincers including butterfly caterpillars that we might treasure.  As an example:
"A 2007 Monarch Lab study determined that C. rufilabris larvae depleted 35 eggs from milkweed in 24 hours, seemingly unaffected by the monarch’s toxicity."  monarchlab.org
So are lacewing larvae good or bad?  Almost any time you hear that question the answer is "It depends."

Tuesday, October 13, 2015