Black Cherry Trees Invade Europe

Black Cherry flowers

We have long known that plant and animal species are successful in becoming invasive when they arrive in a new land without their usual predators.  Now there is more evidence to support this theory.
Black Cherry have long been successful in growing in our forests, sometimes to the point that they are sometimes considered a nuisance species.   Like most native species, they have reached a a balance with their neighbors without out-competing them. Our black cherry trees however have become an invasive species in Europe.
Pythium is a fungal pathogen which causes a disease in black cherry trees called damping-off disease.  The disease kills seedlings in fields and greenhouses.
Studies reported in Sciencedaily.com found that Pythium could be found in 20 comparable forests in North America and in Europe.  However, its ability to kill trees was far less in Europe's forest's strain.

"Reinhart and colleagues tested the virulence of each Pythium isolate. They then used DNA sequencing to identify each isolate. They found that some non aggressive Pythium types were common in both ranges, but aggressive types were found only among samples from the tree's native range."

This study suggests that Pythium serves as a natural control in our forests to keep the population in balance.  Human pathogens such as E. coli and influenza virus vary in their virulence or ability to cause disease.  This is evidence of the same mechanisms in plant fungi.

Egg Shell White?

Wild Turkey Eggs

What looks like a white egg shell to us may be an egg of a different color to a bird.  This is because birds see more color than we do.  According to livescience.com, ultraviolet pigments that are invisible to us may help birds distinguish between their eggs and those of another species.

"Unlike humans, birds can see ultraviolet (UV) light, and they have four – rather than three – color receptors in their eyes, allowing them to better distinguish between hues."

While we can recognized many of the differences between different eggs, we can't recognize the UV spectrum of short wavelength light seen by birds.  Nest parasites such as cowbirds and cuckoos lay their eggs in other birds nests.  Unsuspecting birds may nurture these eggs to the detriment of their own eggs.  Scientists suspect that the differences in UV colors play a part in the recognition and rejection of  these foreign eggs.
The article discusses the coloration of egg shells by two pigments and the mysteries of how and why these developed.  The basic egg is white from its calcium carbonate.  Any color which appears, solid or speckled, comes from a mixture of "blue-green biliverdin, and red-brown protoporphyrin, which are both breakdown products of hemoglobin."

While different colored eggs allows species to detect their own eggs, the colors also may serve to camouflage eggs from predators, act as a sun block or actually strengthen the shell.  Even a single bird's eggs may vary in color as the last eggs may have more speckles as the supply of calcium for egg shells is depleted.  Wikipedia on egg biology

Mysteries remain.  We are all familiar with the beautiful powder blue eggs of bluebirds, yet 5% of nestings produce all white eggs.  At times there is a slight pink or bluish tinge to the eggs but all the eggs will be the same color and produce normal colored chicks.  Apparently a bird will always produce the same color eggs.  If a egg of another color appears in the clutch it was dumped by another bird. 

Bluebird eggs- white

The biology and genetics of bluebird egg color is still in debate.  Some birds hatched out of white eggs subsequently lay blue eggs.  Sialis.org  has a lot more information on the subject.

Horsehair Worm

You may recall the amazing video we previously posted showing multiple parasitic wasp larvae emerging from caterpillars like something out of Alien.  How about an equally startling finding- stepping on a cockroach and facing this creature crawling out of it?  Tim Smith discussed this horsehair worm in his Fresh Afield blog in July.
I have seen these adult worms swimming around the edge of creeks and ponds but wasn't aware of their other life.  Their larvae emerge from eggs and then penetrate their hosts such as crickets, grasshoppers, cockroaches or beetles.  They inhabit spaces between their host's organs, absorbing its blood and lymph borne nutrients through their skin.
After several molts, they are ready to crawl out of their host (or emerge when it is stepped on as above).  They then start a free life in a moist environment, looking for love.  When they encounter a mate, they form a tight knot together, leading to their other name, the Gordion worm.   It is doubtful that they are aware that Alexander the Great sliced through the Gordion Knot or they might try another strategy.
You might think about them the next time you think about killing a cockroach- but I doubt it will stop you.
Details are in Wikipedia.

Dobsonfly is not a Fly

Dobsonfly- click to enlarge

When is a "fly" not a fly? When its name runs together, such as dobsonfly, mayfly, dragonfly, etc.  True flies including mosquitoes and gnats are distinguished by a single pair of wings.  Their common names are always separated such as house fly or fruit fly.
A News-Leader MDC article in July discussed the Dobsonfly (remember, it is not a true fly).  I had just identified one of these which had landed on my truck.  It is uncommon to see these adults which do not eat and live for only a few days.  They are five inches long nose to wing tips which extend far beyond the tip of the abdomen.
The adult male has impressive pincers used to grasp the female during mating.  They are so long that they don't have the leverage to pinch your fingers.  Not so for the female, whose short pointed pincers can hurt you.

Hellgrammite- Wikipedia

Dobsonfly larvae, called hellgrammites, are commonly found in streams and river bottoms and are beloved by stream fishermen.  These primitive looking creatures also come with a set of impressive pincers.  They live up to four years, going through molts and reaching up to four inches in length.  They are apparently considered a delicacy by trout and smallmouth bass and therefore of interest to the fishing set.
The hellgrammite breathes with gills along its sides and lives off of stream creatures which it grabs with its powerful pincers.  Rural children had a measure of bravery. It was tested by putting a finger under a rock and pulling out a pinching hellgrammite before pulling it off with the other hand.  Finally the hellgrammite crawls out of the water to pupate, forming the cocoon in which it will survive the winter.  Come spring, the Dobsonfly will emerge to resume the cycle.

Insect Eggs

Zebra longwing butterfly egg- NG

The latest issue of National Geographic has an story on insect eggs.
You can argue that insect eggs are the seeds of life, for without insects there would be no human life on earth.  Love them or hate them, insects are a critical part of the food chain and the web of life on earth.
These tiny remarkable structures are nearly invisible to us in our daily encounters with nature.  Demonstrating butterfly eggs at Springfield Conservation Nature Center's Insectorama last night, I didn't encounter a single adult who had ever seen an insect egg although they are constantly around us.
Where can you find insect eggs?  Look for them buried deep in wood by the female's ovipositor.  Also in soil, on leaves, floating in the wind, suspended by fine threads or attached to the backs of flies.  Some even lie in water, breathing through long tubes.
Life is hard if you are an egg.  You are a delicacy to surrounding life forms, while others will stick their eggs in you to feed their next generation.
The National Geographic article gives a brief overview of these complex structures.  The whole photo gallery can be viewed at this accompanying web site.

Butterfly House

The Bill Roston Butterfly House at Close Memorial Park has been humming with activity since May.  Actually the hum is more a murmur of amazed children and adults, seeing the whole life cycle of butterflies up close and personal.  Frequently they can see this on a single plant as a butterfly flutters between heads to deposit eggs on a plant all ready hosting several instars of caterpillars.
Occasionally an excited child will point out a new emergence from one of the many moth cocoons or butterfly chrysalis in the house.

Master Naturalists have been heavily involved this year in the project.  Many listed below have served as docents in the house during weekly hours of operation.  Others have manned the Caterpillar Petting Zoo and Lifecycle stations during the Butterfly Festival.  Also some such as Buck and Charley have risked death and injury (well then, maybe ticks and chiggers) while tromping through the wild collecting fresh butterflies for the house.

Hands on Experience

The House is open weekends from 10 AM to 6 PM, Tuesday and Wednesday 5:00 to dark, and to groups by appointment (860-8272). For more information got to
Thanks to the following MN crew:
Rose Atchley, Doris Ewing, Caryn Fox, Carl and Janet Haworth, Karolyn V. Holdren, Sue Jeffery, Connie Johnson, Buck Keagy, Barb and Bob Kipfer, Steve and Linda Kittle, Joe Kleiber, Marlyss Simmons, Carol Snyder and Sherryl Walker.

Plastics Potpouri

Our Oceanic Garbage Patch 
We have all heard of the Great Garbage Patches floating in the oceans.  One question has been why the patches are not increasing over 20 years with increasing plastic production and trash dumping.  This report in Live Science suggests that one reason may be that the plastic pieces are breaking down to particles too small to be retrieved in their nets.  While we may envision a huge floating island of bottles and bags, the area apparently looks normal to the naked eye.  The nets pick up fragments as small as 0.3 millimeters (think a period in this paragraph).  Fragments are sorted and counted by students during the Sea Education Association's SEA Semester annual voyages.

"The term "garbage patch" does not necessarily mean a visible island of trash floating on the waves, researchers said. Only 62 percent of net tows by ships have contained detectable amounts of plastic.

"What we're collecting are really small fragments of plastic from larger consumer items," Lavender Law explained. "If you're on the deck of a ship, you normally can't even see the plastic pieces."

Each half-hour net tow typically turned up just 20 plastic pieces equivalent to about 0.3 grams in all. By comparison, a U.S. nickel weighs 5 grams."

The tiny fragments have bacteria living on them which are not normally found at the oceans surface.  Do the microbes degrade and eventually dissolve the plastic, use it as food, or just a place to attach?  Stay tuned for further research.


BPA or Not-BPA?
 According to a column in "Harvard School of Public Health" researchers have found that college kids who drank from polycarbonate bottles showed a two-thirds increase of the chemical bisphenol A (BPA) in their urine." This has several interesting implications.

The good news is that (a) the levels were slightly higher than a trace, way below the "harmful" range and (b) it was outward bound in the urine.  The bad news is that it did pass through the bloodstream on its way to the kidneys and we don't know how much was stored in fat along the way.  Since we as a nation have accumulated more fat in recent decades, the national BPA storage facilities have increased.  A cynic could say that we may be reducing the environmental levels by our habits.

Does BPA stay in the body?  An article in Environmental Health Perspectives Journal suggests that it does.

"Vandenberg et al. (p. 1055) reviewed 80 published human biomonitoring studies that measured BPA concentrations in human tissues, urine, blood, and other fluids, and found that these studies overwhelmingly detected BPA in adults, adolescents, and children."

Does it matter and what can you do about it?  The risks of BPA in humans is currently unknown.  The article entitled Live Science has information on the numbers on containers that identify which plastics contain BPA.  Meanwhile, recycle and live green as the modern world will let you.