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A Fall Critter Spectacular in the Blue Ridge

Well those lazy, crazy days of summer have given way to cooler fall temperatures and an army of migrants is heading south; those species remaining have to make preparations to survive the winter. We have not yet had a frost, but it will come soon and a view of our front yard shows that leaves are falling, the marsh is browning, and fall asters are the predominant flower seen. Yet there is an amazing amount of life to be seen out and about.

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In the marsh there are lots of webs, especially of the large and spectacular golden garden and banded garden spiders. Many have grown to a considerable size during the summer and I show a photo of one adult female in our marsh. She will be laying her eggs soon which will over-winter while all of the spiders will die with the arrival of frost. Although it may seem sad to us that their lives are so short, they are obviously quite successful and may indeed outlive humans in the long run.

 

Just above the marsh in drier fields the milkweed bugs are congregating on the seed capsules of common milkweed. This photo shows some adults and juveniles together in a group, the function of which is unknown to me. The seeds are a source of food and aggregation could emphasize the bright protective coloration that advertises their toxicity due to consumption of milkweed juices. This group of bugs may also over-winter together in a protected location. Sort of an extended pajama party for bugs?!

 

One of my favorite beetles is the beautiful locust borer which is shown here on some of the last remaining blossoms of boneset. They seem to be a very good color mimic of the ferocious yellow jacket wasp which few animals other than skunks are willing to tangle with. Females lay eggs in the bark of black locust trees and the young will hatch, feed as larvae, and pupate the following summer and emerge as adults the end of the summer to start the cycle anew.

 

One of the strangest insects you may encounter is this monkey slug, the larval stage of the hag moth which I found on a leaf in our yard. It is difficult to even tell that it is a caterpillar and there is an intriguing hypothesis that the unusual shape is a mimic of a cast skin of a spider/tarantula. The adult female moth is a bee mimic and the male a mimic of a wasp. So the same organism is a mimic of three different animals depending on its age and sex, a remarkable example of the power of mimicry in deterring predation.

 

A caterpillar well known to everyone is the famous "woolly bear" which is an immature Isabella tiger moth. Few would recognize the adult moth but all children are familiar with the cute and cuddly caterpillar which dies not sting and is commonly seen this time of year moving about, possibly to find a site for over-wintering. Although the exact reason for so much movement is unclear, legend has it that the width of the orange band will predict the severity of winter. Of course this is not so, since not even the weather service has figured out a fool-proof way of predicting the future. There is much variation in this trait as well as changes during the growth of the caterpillar.

 

Several years ago I planted five small catalpa trees and three have begun to grow rapidly. To my surprise and excitement one small tree had a group of this catalpa sphinx moth caterpillar feeding on the leaves. A few of the caterpillars had the cocoons of parasitic braconid wasps attached to them; the wasps had fed on the caterpillar, pupated in the cocoons, and emerged as adults as can be seen by the small holes at the ends of the cocoons. Anyone who fishes for bass may be familiar with the use of this caterpillar as a bait; indeed I first encountered them when a fishermen on the New River gave me some extras he had although he called them "bean worms" in reference to the seed pods of the tree. I intended to use them not to catch but to feed my bass in a pond next to my house- the photo shows one of my "pet bass" which follow me around the pond edge. This apparently is a learned response to the fact that frogs jump into the pond when I walk by and the bass gets a free lunch. When I threw in a catalpa hornworm, it was immediately gobbled up by a sunfish- it may be too small to interest these large bass.

 

One of the prized migrant birds we watch for every year at this time is the marsh wren. This bird was photographed in a pond in front of our house which is densely planted with pickerel weed with some willows and bushes around the edge. The marsh wrens (at least two were present) are very secretive as are the sora rails which are also stopping as migrants in our marshes. They arrive on a very reliable timetable year after year.

 

One of the most unexpected wildlife observations I had this week was an encounter with two moles which were fighting very viciously. Who would have thought that moles (possibly two males in a territorial conflict) had more than worms and grubs on their minds? I scooped them into a bucket and they still continued to bite one another with great intensity. I show a photo here of the rarely seen front end of the mole illustrating the huge front feet for digging, the movable nose and the absence of obvious eyes (they are buried in the fur). Most people hate moles because of the burrows and holes they dig in lawns but they are our best biological control against the grub larvae of beetles that are quite destructive to lawns and shrubs.

 

So while I have been expecting that fall would soon bring down a curtain on wildlife activity, I have so far found just the opposite. Although the species involved and their behavior are different from the summer, the intensity of species interactions and the numbers of animals moving around and preparing for winter is impressive.

 


Bill Dunson
Galax, VA & Englewood, FL

wdunson@comcast.net

http://www.galaxgazette.com/blogs

http://lemonbayconservancy.org/dunson_archives.htm

http://lemonbayconservancy.org/wildflower.htm