With September comes the end of summer.† Birds are migrating south, social bee colonies are collapsing, ground hogs are settling down for a long winterís sleep, fawns are losing their spots, and the bucks are rubbing off their velvet, getting ready for next monthís rut.† Ant colonies now produce winged males who will mate with queens in large clouds of flying workers, males and queens.
Yet, the warmth of September tells us summer is still with us.† The open fields and meadows support much seasonal activity.† Flowers of the composite family, such as goldenrods, asters and thistles dominate the scene.† Gentians and ladyís tresses orchids are found in the wet meadows of the higher elevations.† Second broods of butterflies and moths still search for pollen, nectar, and mates.† And the hard mast of oaks and hickories are being greedily downed by birds, insects and mammals alike.† Yes, nature is busily readying itself for the coming season of energy deficiency.
The forests abound with the common white wood aster and white snakeroot.† Itís also the prime time to search for ginseng in the forests, easily spotted by the bright red berries.† The porcelain white berries of dollís eyes can also be found at this time.
One thing I look forward to at this time of the season is the massing of walking sticks.† Iíve seen literally hundreds on a six-foot red cedar tree in old fields.† More often, lesser numbers are found (or, more often, overlooked) in wooded environments.† Of course, these large gregarious congregations are for the purpose of mating, with females dropping about 100 eggs from the shrubs onto the ground, where they will over winter in the duff of the forest floor.† Unlike most large insect families, there are only 8 species of walking sticks that exist in North America.
September is the month for listening to grasshoppers, crickets and katydids.† These members of the Orthoptera Class number some 1,000 species in North America.† Primitive insects, they have spent the summer molting through about five instar stages until this time when they metamorphose into adults. It is only at this time that they develop wings and sexual reproductive parts. The musical sounds of the crickets and the lower-pitched scraping sounds of the grasshoppers are made by the rubbing of the scraper of one front wing against the file on the other front wing. In the case of crickets, the songs are also warnings to other males to stay out of their territories.† This aggressive attitude is so pervasive; it has led residents of Asia to raise fighting crickets as a sport.
The sounds of crickets are quite descriptive.† There is even a CD recording of Orthopterans.† The mating calls, made generally by males only, increase in pitch and speed as a function of increasing temperature.† In fact, several of the species, including the common snowy tree cricket and field cricket can be used to determine the temperature.††
For the most part, grasshoppers, crickets and katydids complete their life cycle in one year, over wintering as eggs.† This is a far cry from the longest living insect, the 17-year cicada, which lives as a nymph on tree roots for seventeen years prior to their mass exodus.† Of course, last spring was our regionsí opportunity to experience these wonders of the natural world.† I have heard from a few people who heard the 17-year cicada this spring.† Itís not surprising that a few have genes that enable them to emerge a year earlier or later.† Thatís how nature adapts to environmental change.
Speaking of fall insect sounds, the annual cicada dominates the diurnal forest community.† The name notwithstanding, this cicada we hear every year does not have a one-year cycle.† They live on tree roots for about three years before metamorphosing into screaming adults.† Itís just that there are numbers that metamorphose every year, so we hear about a third of the total population every year.†
If youíre into astronomy, check September 17 on your calendar.† This is the full moon known as the Harvest Moon.† I had always heard the moon rises about 51 minutes later each night, but I now know this is only the annual average.† Take a look at the table below (taken from the NASA Science website).† Youíll see that the moon rises 70 minutes later each night in January, and only 30 minutes later at this Harvest Moon.† This is a function of the small angle that the moonís path (ecliptic) makes with the eastern horizon in early autumn.† Only at this time of the year does the Earth, sun and moon line up so that the plane of the moonís orbit is at a low angle to the eastern horizon.
You may also notice that the moon seems to sit near the horizon for a long time.† This is also a function of the low path of the moonís orbit at this time of the year.† Near the spring equinox, the moon will rise in the Northeast at about an angle of 73 degrees, so it appears to rise very quickly.† At this vernal equinox, the angle is only 27 degrees, thus, it appears to stay near the horizon for quite some time.
One more thing you might notice about our Harvest Moon.† It often shows hues of orange and red.† The reason for these hues is the same reason we have orange and red sunsets.† Itís all about the wavelengths of color as it comes from the sun.† Blue has very short wavelengths while red has very long wavelengths.† Having short wavelengths, the blue light will hit more particles in our atmosphere than the longer wavelengths of red.† Thus, at sunset (or when the moon is near the horizon reflecting sunlight to earth) most of the blue wavelengths are scattered by the thick atmosphereís particles up into the sky.† What we see are more of the longer red wavelengths, which are reflected less than the blue.† This same phenomenon is responsible for our blue skies.† The longer red waves come straight down to the earth, while the blues are bounced around in the sky, thus making up a larger proportion of the visible light rays in the daylight sky.