The lazy, crazy days of summer have given way to cooler fall temperatures sending an army of migrants heading south to make preparations to survive the winter.
The first frost will come soon, leaves are falling, the marsh is browning and fall asters are the predominant flower. Yet there is an amazing amount of life still to be seen out and about our farm in Galax, Va., before we head south soon ourselves to our Southwest Florida home.
In the marsh there are lots of webs, especially of the large and spectacular golden garden and banded garden spiders. Many grew to a considerable size during the summer.
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The rare marsh wren makes annual migrations.
An adult female in our marsh will soon be laying her eggs soon - all of the spiders will die with the first frost. Although it may seem sad their lives are so short, they are obviously quite successful and may indeed outlive humans in the long run.
Milkweed bugs are congregating on the seed capsules of common milkweed just above the marsh in drier fields. Adults and juveniles group together for a function unknown.
The seeds are 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. It is sort of an extended pajama party for bugs.
Fact Box
William Dunson, Ph.d., professor emeritus of biology at Penn State University, splits time between Southwest Florida and his farm in Galax, Va. He can be reached at wdunson@comcast.net.
The beautiful locust borer, drawn to the last remaining blossoms of boneset, is a good color mimic of the ferocious yellow jacket wasp, which few animals will tangle with other than skunks. 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. It is difficult to tell it is a caterpillar. 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 does 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. 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 catalpa sphinx moth caterpillars feeding on the leaves. A few caterpillars had cocoons of parasitic braconid wasps attached; the wasps had fed on the caterpillar, pupated in the cocoons, and emerged as adults through 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 -my "pet bass" 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 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 and some willows and bushes around the edge. The marsh wrens are secretive as are the sora rails, which are stop as migrants in our marshes on a reliable timetable year after year.
One of the most unexpected wildlife observations this week was an encounter with two moles fighting 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 quite destructive to lawns and shrubs.
So while fall is expected to ring down the curtain on wildlife activity, it does just the opposite. Although species and their behaviors are different from summer, the intensity of species interactions and the number of animals moving around and preparing for winter is impressive.
