Monday, September 15, 2014

Ants and Scale Insects

If I’m just out looking around, I never fail to investigate anything that draws the attention of the Allegheny Mound Ants.  If the ants are involved, there is undoubtedly something of interest to be seen.


In this case, I was led to a colony of Scale Insects.  Scale insects spend most of their lives immobile on the branch of a tree and create a thick dome-like casing that hides their entire body.  They feed by drawing sap from the tree through a tube shaped mouth that is permanently imbedded into the tree’s bark.  These were feeding on Tuliptrees, Liriodendron tulipifera.  I’m going to go out on a limb here and call these the Tuliptree Scale, Toumeyella liriodendri.


The affected trees were all small and growing out in the open.  A large colony of sap draining insects could cause severe damage to a tree of this size.


Despite their protective covering, Scale Insects are plagued by many predators.  Fortunately for the Scales, the ants are on hand to ward off any potential threats.


Guard duty is not a free service.  It is a benefit resulting from the ant’s actions to protect a valuable source of food.  Like many sap consuming insects, some Scale Insects produce a sugary byproduct called Honeydew that is regularly secreted.  The ants are quick to imbibe this liquid as soon as it becomes available.  The ant on the right in the above photograph has an abdomen distended to a point of semi-transparency by honeydew.


Large Tuliptree Scales found during this time of year are all female.  They are just reaching the end of their year long life cycle and like this one, are soon to die and fall from the tree.  As the immobile females develop, they lose many of their extremities, but the three basic insect body parts are still recognizable.  In the above photo of the underside of a mature Scale Insect, the head is toward the top and the sections of the abdomen are still visible in the lower half of the body.


 
The female of this species holds the developing eggs inside her body until they hatch.  The newly hatched insects are then held inside the waxy shell until they have developed enough to strike out on their own.  The dark mass to the left is a mass of developing eggs.  Eggs hatch and young are released over a two to three week period.  When the last of the eggs has hatched, the female dies.

The young crawl from beneath the shell and spread out over the tree.  Once they find a suitable site, they will attach themselves to the bark and begin feeding.  The females will never move from that site.  Males will form a shell in which they will pupate next spring. Sometime in early summer, winged males will emerge and search out females with which to mate. 


Females typically grow a dome with a large oval-shaped base.  When conditions get crowded, irregular shapes are formed to fit available space.


The ants have gathered cedar needles and used them to form a temporary shelter at the base of the scale infested tree.  The ants will use this as a base as long as there is honeydew to be collected.
 

Construction of temporary nests is a common activity among Allegheny Mound Ants.  I’ve seen them make these shelters anything from baseball to basketball sized and use them for weeks or months before once again merging with the main colony.  I have yet to see any activity that gives clues to how the bounty collected by this satellite group is shared with the colony.  I may just have to camp out with the ants until I figure it all out.

Friday, September 12, 2014

Army of Caterpillars - Datana ministra

Now for more hungry caterpillars.  This is Datana ministra, in the same genus as the Major in the previous post.


I found this species feeding on a small Blackjack Oak, Quercus marilandica.  It was evident from quite a distance that this tree had seen caterpillar damage.  Many of the upper branches were left with nothing but stout petioles where there should have been leaves.


The caterpillars are all final instar and have spread throughout the tree.  They are numerous enough to defoliate an oak of this size.  I made a count of nearly 50 individuals and may have missed a few.


Body size and shape is nearly identical to D. major, but the coloration is not nearly as bright.  The body is basically black with several yellow lines.

This species is commonly called the Yellow-necked Caterpillar.  Yellow just behind the head along with this showy orange patch are responsible for that designation.


These caterpillars displayed an interesting feeding strategy.  A pair would team up, with members of the pair working opposite sides of the leaf.  The result is a leaf that still retains its balanced shape.  Many predators search out caterpillars by targeting irregularly shaped leaves resulting from caterpillar feeding activities.  Synchronized feeding helps hide the fact that the leaf is being consumed.


The effects were not always perfect, but the result usually looked much like a naturally formed leaf.


This pairing was not an isolated incident.  Many feeding pairs were found on the tree.


The pair would feed until there was no leaf left and then would back down the petiole and move off to another leaf.


Of course, the plan was not always executed perfectly.  When three caterpillars end up on the end of the same stalk it begins to get silly.  We should stop here before things get out of hand.

Wednesday, September 10, 2014

Army of Caterpillars - Datana major

Caterpillars eat.  Their life is one of consuming and processing food until they move on to the next step of development or are themselves eaten.  Towards the end of summer, when the nights begin to get cool, caterpillars seem to go about their task with an increased sense of urgency.  Most will survive winter as a pupa and they must reach that stage before temperatures get low enough to bring their metabolic processes to a halt.


I imagine there are caterpillars in every tree or shrub you see.  Add to those the multitude of species that feed on grasses and forbs and I doubt that you are ever very far from a caterpillar when in the field.  The trick is in finding them.  This Deerberry shrub is showing signs of the recent dry weather.  Dead leaves are piled beneath the plant and live leaves all show signs of discoloration.  I wouldn’t pick this as the most likely place to find caterpillars, but I always give the Deerberries a check when I’m out.


The view from three feet away reveals what was totally obscured at ten feet.  The shrub is full of caterpillars.  These are larva of the Major Datana Moth, Datana major.  Early instars of this caterpillar are gregarious and feed as a group.  When they reach their final instar, they tend to disperse and feed individually.


It’s hard to imagine such a brightly colored creature blending into its surroundings.  The pattern however, does harmonize with the mosaic of greens, reds and browns in the leaves and the grays and blacks of the stems.  As you come into range, the materialization of the caterpillar image is similar to the moment your eyes reach the proper degree of focus to reveal the subject of one of those 3D Magic Picture prints.  It’s a definite “Ahhh” moment, not to be confused with the more cerebral “Ah-hah”.


The appearance of the caterpillar changes as it moves from one instar to the next.  The individuals with black bodies and broken white stripes represent the final instar prior to pupation.  The brown and white striped caterpillars will soon be proceeding to that final instar form. 


The profusion of cast off skins indicates that the transformation to final instar caterpillars has been a recent event.  These fragile skins are easily dislodged by wind or rain.  In fact, several fell from the branch as I maneuvered it for better viewing.  We haven’t had rain, but the open field in which the Deer Berry grows has experienced an abundance of wind.


Leaves are rapidly disappearing from the  Deerberry.  Dispersal of these larger caterpillars is necessary in order for each individual to feed without disturbance.  The caterpillars have moved out through half of the shrub and a few individuals have arrived on neighboring shrubs.  They will soon make their way to the ground where they will create a chamber in the earth in which to pupate.  Adult moths will emerge next spring to begin the process anew.


The red legs become quite visible when the caterpillars are positioned below the branches.  It’s interesting that so many colorful caterpillars eventually emerge as drab adults.  For some reason, the coloration of these caterpillars makes me think of 1950’s era vinyl patterns.


The hairs on this caterpillar serve no defensive purpose.  When threatened, the caterpillar raises its head and tail with thoracic legs thrust upward like horns.  In addition to the threatening appearance, a bit of ingested material is regurgitated at the mouth and a droplet of liquid is released from the anus.  I’m assuming that both of these substances are unappealing in some way to predators.  The anal droplet is visible in the photo as a honey colored sphere on the end of the upraised tail.  Quite an interesting little creature.

Monday, September 8, 2014

Horseflies

This has been a great year for Horseflies.  By that I mean there are a lot of them around.  I realize that many people would prefer this particular nuisance disappear entirely and to them I imagine this would be a bad year for Horseflies.  I have always been fascinated by these large flies and enjoy having them around.


My favorite species has always been the Black Horsefly, Tabanus atratus.  This beauty with its soot black finish appears to have been assembled by fine craftsmen.  Female Horseflies feed on fresh blood, primarily taken from large mammals.  Males feed on nectar and pollen and I suspect sweat, since I’ve been buzzed by male Horseflies that land on my sweaty shirt, but do not bite.


The key to sexing Horseflies is the space between the eyes.  The eyes of the male meet on the top of the head.


In the female, there is a spacer that separates the eyes.


I believe this is a female Tabanus calens.  I’m quite impressed with the brightly colored antennae.  Their shape reminds me of some Klingon weaponry, but these are sensory organs, not defensive structures.


If there is any weaponry involved with the Horsefly, it would be the cutting mouthparts protected by the two light brown sheaths located below the antennae.  The cutting mouthparts pierce the skin to allow the blood to flow.  The blood is then taken up by the labella, that dark sack-like structure located below the sheaths.  Human blood is readily taken by Horseflies, much to the discomfort of the donor.  Fortunately, the larger species of Horseflies are quite noisy in flight and can be heard long before they settle down to bite.  I’ve noticed that if you wave and swat at a circling Horsefly, it just widens its circle until you calm down.  If you catch the Horsefly in your hand, hold it for a moment and then release it, it will fly straight away and not come back.  That bit of information probably won’t help many people cope with their Horsefly encounters, but it is interesting.


Most literature states that Horseflies lay their eggs in or near water on plants and rocks near the shoreline.  I’m used to watching Horseflies cruise above small pools and suddenly drop down to smack the water and fly quickly away.  They have been making daily assaults on my Water Garden for the past several weeks.  The image above is the closest I could come to capturing this activity.  I have always assumed that these flies were females depositing eggs, but I’ve never read anything that affirms that assumption.


Maybe smacking the water is some type of cleaning activity intended to rid the flies of external parasites.  Carrying along a mite of two seems to be all the rage this season.  I can’t remember when I’ve seen so many of these red riders on the bodies of large flying insects.  Some may be permanent residents and others just hitching a ride.  Whatever they’re up to, they always make their host a bit more interesting.

Friday, September 5, 2014

Fence Repairs

Along one mile of my property line is a fence that has been in place for close to 50 years.  The effective lifespan for a fence expected to contain livestock is 20 years.  Since my neighbor and I neither have livestock, the fence needs only to serve as a visual indicator of where the two properties join.  This fence is primarily bordered by woodland.  The combination of falling trees and deteriorating posts results in a fence that sags and at times lays flat on the ground.


The fence wire is rusty, but is still strong and functional.  I periodically select a section of fence where I will splice broken wire and replace non-functional posts.  This year I chose an 1100 foot stretch and spent five days cutting and setting posts, cleaning obstructions from the fence line and attaching the fence to the new posts.


Posts are cut from cedars in the woodland that died long ago from lack of sunlight and have stood long enough since death to lose their outer coating of bark and sapwood.  A typical tree will give three eight foot posts with diameters ranging from eight inches at the base to four inches at the top.  The red inner wood of these posts is rot resistant enough to survive for many more decades.  Notched poles are used to hold broken posts in place until I’m ready to attach the fence to the new posts.


My primary fence building tools are the spade, spud bar, and posthole digger.  The star of the show, and the tool I would most like to leave in the barn, is the 18 pound spud bar.  The chiseled end is used to break up rock encountered while digging postholes and the flattened end is used to tamp in the earth used to fill the holes after post placement. 


This is a common sight in most of the postholes.  Shallow bedrock is responsible for the conditions that allow such a diversity of rare and unusual life to exist at Blue Jay Barrens.  I remind myself of that fact as I chisel away at the rock with my spud bar.


My work is helped along somewhat by the condition of that rock.  The meteor that hit this site 350 million years ago fractured, and in some cases pulverized, the bedrock.  Much of the time, I’m able to break out chunks of rock by applying pressure to already existing cracks.  There are times though that the spud bar rebounds from the rock with the sound of a clear chime and I know that I’ve found a bit of rock that is both massive and unbreakable.


Even when it does break apart, dealing with rock is tedious and time consuming.  Sometimes I accumulate a nice pile of rocks.


In some locations the limestone bedrock occurs in thin beds sandwiched between clay.  These beds, usually an inch or less thick, eventually yield to the spud bar.  Getting the first break in each layer is the hard part.  After breaking through, it’s fairly easy to chisel an opening large enough to accommodate a post.


The most uncommon experience is to encounter no rock at all.  This was my only rock free posthole.  It just served to remind me of how quickly I can set a post when I don’t have to deal with rock.  That made the rock filled holes that much more aggravating.


The fence isn’t pretty, but at least it’s recognizable as a fence.


I’m pretty good about staying on task while I’m out working, but occasionally I’ll take some time to look at nearby things of interest.  I was wondering why there always seemed to be a shaft of sunlight breaking through the tree canopy at just the place I was working, when I noticed the chewed condition of these Prickly Ash leaves.


It didn’t take long to find the cause of the chewed leaves, the caterpillar of the Giant Swallowtail butterfly.  This is one of those bird poop mimics and its camouflage is quite effective.


I had to pull the branch down in order to photograph this guy and in the process, I annoyed it enough that it displayed its red osmeterium.  The osmeterium is a defensive mechanism designed to discourage predators not put off the bird poop appearance.


I also found several clumps of Indian Pipe just beginning to emerge.  Indian Pipe is a saprophytic plant that lacks chlorophyll and harvests its energy from decomposing organic matter.


I had my own fan club of Hackberry Butterflies.  These butterflies love to lap up sweat and I sweat enough to support legions of these guys.  Most of the butterflies were going for my back and shoulders, but a few found that I had imparted enough sweat to my tools to make them a convenient place for a drink.  Though they seemed to have abundant energy, none of the butterflies helped with the fence building in any way.