Nature Blog Network

Monday, July 28, 2014

Arrowhead Spider

A trip through the woods this time of year includes eating a lot of spider webs suspended between the trees.  Many spiders are hard to identify without close inspection of their eyes, palps, etc.  One of the most common species that ends up dangling from my clothes is this distinctive spider with its sharply outlined light colored triangle.

V. arenata - legs tucked up
This is a female arrowhead spider, aka triangular orb weaver, Verrucosa arenata.  Only the females have the bright triangle on the dorsal abdomen, varying between white, yellow or orange, its tip pointing away from the head.  The males have no distinctive characteristics, don't build webs, and are only found on the females' webs during courtship and mating.

It typically builds its web at head height, making it one of the most commonly seen species. Unlike all the other orb weaver spiders which cling to the web head down, V. arenata is usually found head up.*  Another distinctive trait is its tendency to sit with its legs tucked under the body instead of extended.
Spined Micrathena - Micrathena gracilis - female
Spiny Orb Weaver - Photo by Richard Hover
M. gracilis - Wikimedia
Another common spider found on the trails is the spiny orb weaver, Micrathena gracilisIt is also called the CD spider as its tightly woven circular web can look like a CD when the light is right.  The spider's huge abdominal structure is frequently confused for something that it has captured and is carrying away.  Although this growth seems cumbersome and energy wasting, it apparently serves its unknown purpose.  The male has much smaller spines.  It is usually only seen while mating and often ends up being eaten, giving a whole new meaning to a "dinner date."

In both species only the females build webs; circular structures suspended vertically from strong silk lines stretched across trails and openings between woody vegetation.  These are pathways frequented by small flying insects and incidentally, humans.  They specialize in tiny flying insects like mosquitoes, gnats and flies.  After the prey hits their sticky, closely woven silk, the spider bites it, injecting its venom which digests it internally.  The spider then returns later to suck up its predigested juices.

The female needs all the energy she can get as she will continue to produce egg cases as long as the weather holds.  The adults die over the winter and the new generation emerges from the egg cases the following spring to continue the cycle.

More research on V. arenata's head up position and its effect on speed and web construction is at this Pubmed article.

Details on the arrowhead spider are at this MDC xplore page.




Thursday, July 24, 2014

Mushroom Flower

"Mushroom Flower" - Gerronema strombodes
Michael Baird found this mushroom on our hike.  From a distance it looks more like a flower than a fungus.  I couldn't find it in any of my field guides and turned to my friendly neighborhood mycologist, Mark Bower.  He also initially struck out and sent it to MOMS site (Missouri Mycological Society) where it was identified as Gerronema strombodes.


You would think that a striking fungus like this would have a common name and in absence of one, I am naming it mushroom flower.  It is the most commonly found of the uncommon to rare Gerronema species in the Eastern US.  

G. strombodes is a saprophytic fungus, growing on decaying wood.  It is usually found during damp periods.  Michael Kuo at MushroomExpert.com gives a colorful description of his first attempts to identify it.  He too was led on a merry chase including translating a description from German.   His extensive description gives you an idea of some of the features used to differentiate the species.

 

Most experts discourage trying to identify a mushroom by thumbing through a guide looking at pictures, so it was refreshing to read that even the great are occasionally reduced to my most common method when "keying out" fails.  A simple example of a mushroom key is this one from Kuo.

Using a key is becoming a little less daunting with computer programs such as MycoKey but you still have to learn the descriptive language.  Or you contact a friend.  Sometimes who you know trumps what you know.



Monday, July 21, 2014

Harlequin Bug


Harlequin bug eggs - Nathaniel Gross
Several years ago, Adam Millsap sent me the picture of harlequin bug eggs like those above on the underside of his kale at Urban Farm just a few blocks southwest of the Springfield square. They are stacked together in bunches of 8-10 like miniature barrels.  As he noted, they are so beautiful that he hated to crush them, but as he grows veggies for a living, crush them he must.

Harlequin bugs mating - Scott Nelson
Only the adult survives over winter. They emerge early in the spring, just as we are preparing our gardens. They lay around 12 eggs together in a line resembling a row of kegs with black hoops.  The eggs hatch in 4 to 28 days depending on the temperature.

Harlequin bug nymph-ventral - REK
Harlequin bug nymph - REK











The nymphs go through 5 to 6 cycles (instars) before they become adults.  These stages progress from pale orange to black with distinct orange and white decorations.  The sexually mature adult develops the most showy colors.  They are 3/8 inch long, a flattened oval shape with crossed wing covers forming a "V."

Even their belly is beautiful - REK
Adult harlequin bug - REK









The harlequin bug (Murgantia histrionica) is a serious pest which attacks cabbage and related species preferentially, although it is capable of attacking almost any garden crop and even fruit trees. Unlike beetles which chew leaves, they suck the juices which tends to kill the whole plant.

Adult harlequin with a single egg - REK

Brightly colored insects are frequently advertising that they are bad tasting or toxic (think Monarch butterfly).  This is called aposematic coloration the bird version of a skull and crossbones sign.  While sometimes insect color is deceptive, the harlequin bug eats crucifer plants (cabbage, brocolli, etc.) and not only absorbs their glucosinolates which are toxic to birds, but is able to concentrate and store it within its tissues.  I can just hear a mama harlequin saying, "eat your veggies or a big bad bird will get you!"

These are a type of stink bug, so pinching them with your fingers may come at an olfactory cost.  Of interest, the harlequin bug originated in Mexico and was first reported in Texas in 1864.  Its progress northward was followed and reported through the turn of the century and it now occurs across the US, generally south of Colorado and Pennsylvania.

Hand picking the bugs, larvae and eggs may prevent the recruitment of large armies requiring chemical measures.  Given their destructive habits, I can forgive Adam for destroying this mobile form of art in his garden.
More at this link.

I want to acknowledge all the "amateur" naturalist photographers like those above who post their works on Bugguide.net and graciously allow us to use them.  Much of the entomological identification and public education is being performed by passionate non-professionals like these.

Thursday, July 17, 2014

A Fringetree for Your Yard

C. virginicus in bloom - Wikimedia
From Jennifer Ailor, Master Naturalist

Fringetree range - Wikimedia
For years I’ve heard about the beautiful but rare in these parts fringetree, Chionanthus virginicus L. It’s a native of the south and eastern U.S., whose northwestern range just barely reaches into the border country of southwest Missouri/northwest Arkansas. I finally bought one from Wickman’s Gardens in Springfield, though Garden Adventures of Nixa also carries them.

My tree bloomed the first year: lacy clusters of fragrant white blossoms hanging in fringes like finely shredded strips of paper. What a beauty! Mine bloomed in early May both years I’ve had it, lasting for about two weeks. The tree can grow to more than 30 feet in the wild, but in gardens 12-20 ft. is more common.

The tree grows in full sun to partial shade and prefers moist, fertile soils. In the wild, you’ll find it in rich, moist woods and hillsides, moist stream banks, limestone glade margins and rocky bluffs and ledges, according to the Missouri Botanical Gardens. You’ll need to water it in prolonged droughts.

The tree is dioecious (separate male and female plants) but may have flowers on each plant. Male flowers are more showy. Fertilized female flowers produce clusters of olive-like fruits that ripen to a dark, bluish black in late summer—good food for birds and wildlife. Mine must be a male tree because I haven’t seen any fruits.


Waved sphinx moth - REK
Editor's note:
As an added benefit, the fringetree is a host plant for larvae of the rustic, waved and fawned sphinx moths.  We commonly see the waved sphinx moth, Ceratomia undulosa at our deck light along Bull Creek.  By a wild coincidence, Chris Barnhart just sent me these pictures of the C. undulosa larvae just after hatching.


Hatchling C. undulosa larvae - Chris Barnhart

Later instar C. undulosa larva - Chris Barnhart

Monday, July 14, 2014

Ants in the Mail


After 30 years of using the same mailbox, suddenly over 24 hours these ants and pupae appeared.  One day no ants, next day filled. The box is in a brick structure with a board on the base of the box which has been slowly disintegrating over the years. It had been raining heavily daily x 3 but the box and inside structure was dry. There were no ants on the outside.


Curious to learn more, I sent the pictures to my myrmecologist* James Trager who promptly sent me this reply. "Every spring, these same ants - Tapinoma sessile or Odorous House Ants show up in the mailbox, in stacks of flower pots and various other places up off the wet, cool ground, in order to incubate their brood. "


Our ants closeup -  REK
The Odorous House Ants, Tapinoma sessile, act like they have had way too much sugar, and indeed they have.  Their primary food in nature is honey dew, the sugary liquid produced by scale insects and aphids as well as plant nectar.  When humans came along they found another source of "honey dew," in kitchens and garbage.   Just like squirrels, crickets and mice, they liked what they found and moved in with us.  They will also eat dead insects when available.

   T. sessile  Tom Murray
Dr. Eleanor** describes the species in her own colorful way.  Rather than biting to defend themselves, they run around erratically, spraying a defensive odorous fluid from their anal glands.  She describes the odor of a squished ant as smelling like blue cheese.  Fortunately I had sprayed them first and thus didn't chance ruining my taste for salad dressing.

Odorous house ants have a habit of moving their nest every few weeks which may account for how they showed up overnight in our mailbox.

* Word for the day - myrmecology - the scientific study of ants.  James Trager is a member of the AskAnt Team.  They answer questions on an interesting blog at antweb.org/antblog/.
** If you are yearning to learn more about ants or even become an amateur myrmecologist, a great free I-book, Dr. Eleanor’s Book of Common Ants
is available on line here
More detailed information on T. sessile is available at this link.




Thursday, July 10, 2014

Black Trumpets


We were hiking through the woods with Michael and Teri Leigh Baird when Michael pointed to the scattered black spots, looking like holes in the dark moist forest floor.  These were the famous black trumpet mushrooms, Craterellus cornucopioides.  They are notorious for being hard to see, even if you are looking for them.  Once we learned to focus on them we found trumpets in clusters scattered all around on the damp dark soil.

Find the trumpets - Click to enlarge
Black trumpets may start life as light brown, turning black with time. They are said to be associated with oaks but there is some debate over whether they are mycorrhizal (associated with tree roots) or purely saprophytic, breaking down and recycling dead vegetation in the soil.  Either way they are usually found on moist shaded soil in the forest, sometimes associated with moss.


They are highly sought after as an edible mushroom.  Maxine Stone in our edible mushroom bible,  Missouri's Wild Mushrooms*, gives them her highest **** "choice" rating.  They can be preserved by drying which we resorted to after finding five pounds of them.  She has recipes for using them in soups and egg dishes.

MDC Nature Field Guide
More on Black Trumpets from Michael Kuo.
*Great information and recipes.   Missouri's Wild Mushrooms

Monday, July 7, 2014

Male Black Widow Spider's Rhythm

Black widow spider dorsal view - Click to enlarge
A recent story on Nature World News described a set of "good vibrations" produced by the male black widow spider, Latrodectus mactans.   Like many other spider species, the female black widow may eat the smaller male that is coming in to mate if his intentions are not perfectly clear to her. Many spider species have distinctive mating rituals or courtship signals.  Not so the male black widow which relies on rhythm.  When approaching the female, the male shakes her web at a particular frequency, signaling that he is coming to mate and not coming as dinner. 

Unlike the way we were traditionally taught, the female black widow doesn't commonly eat its mate, the basis of its name "widow."  Any insect or other prey, including other spiders, will set off a vibration by their touching the web.  The research, published in Frontiers in Zoology, found that the male black widow consistently produced a distinctive web vibration, creating low-amplitude ‘whispers’ of love.   This gives a whole new meaning to the term "safe sex."

Black widow egg cases - click to enlarge
I was reminded of this research when I got a call from our neighbor Sheila who had found what looked like a black widow but was "too big."  It was guarding two egg cases and it looked too big to me also.  I had to manipulate it for some time before I could see the distinctive ventral abdominal red hourglass.

Black widow egg cases and spiderlings - click to enlarge
I put the egg cases in a small plastic box, sealed to prevent their release in the creek house and an early end to our marriage.  The next day we had a whole box full of spiderlings, suspended in a 3-dimensional array with tiny strands of silk.

Black widow spiderlings - click to enlarge
The hatchlings are light colored and become darker with each molt until they reach the smooth black color of adulthood.  The female's abdomen is globose (round) while the male's is more oval.  Females' abdomens are said to be wrinkled and somewhat deflated after they have laid their eggs and spun the sacs.  A female may have 3 or 4 egg sacs at one time, each containing anywhere from 100 to 900 yellow eggs.  As our spider was still tightly globose and had only two egg sacs, I suspect she wasn't through her cycle yet.  Over a lifespan of 1 to 2 years a single female may produce 9 to 15 egg sacs!  No wonder she can looked shriveled.

More detailed information on L. mactans is at www.spiders.us.