Summer is in its waning weeks. The birds have gradually stopped singing. The red maples have started to shed a few leaves, while the oaks and hickories are laden with mast. The squirrels can’t wait for the nuts to fully ripen and have already start cutting them from the trees.
The sun sets noticeably later now than it did just a few weeks ago. The sun shines also shines at a noticeably different angle, leaving shadows upon the foliage. The broom sage is in flower. In a few weeks, the ugly stalks of that pernicious weed will dry, leaving ugly stalks that will reach above the fluffy blankets of the first snows.
From the pods on the milk weed to the screams of the blue jays, everything points to demise of summer. But summer never goes out without a recessional.
And every year, that recessional is played by the same orchestra. In the meadow grasses, the field crickets sing their courting songs. All summer, one could hear their faint chirps, and as the crickets reproduced, they have grown in numbers. Now, their little chirps are are a veritable cacophony that rises from the pastures and roadsides.
The katydids rock out in the night. Because they are so beautifully camouflaged, they are rarely seen. However, there must be thousands of them singing their mating call, which seems to sound like an argument between two people- one seems to say “Katy did” then the other seems to say “Katy didn’t.”
But the main instrumentalists who sing away summer are not the crickets, the katydids, or the jays. No, the sound that dominates this orchestra resonates from the trees. It is an alien sound, half buzz and half hiss, which rises in its intensity with the heating of the day. The hotter the day becomes the louder this sound rises through the forest.
Of course, I am talking about the annual or dog day cicadas (Tibicen) . When I hear these insects, I know that summer has begun its swan song.
They have spent two or three years as ugly nymphs. They lead a subterranean existence under the forest floor and live on a diet of tree roots. After those three years, on some late July or early August night, they arise from ground and climb up the tallest trees. Then the backs of their thoraxes split apart, and from the that split, a winged insect emerges. The nymphs are now in their adult form called an imago. They leave behind their little exoskeletons that they had as nymphs, and when I was growing up, I used to collect the cast-off exoskeletons beneath the bigtooth aspen trees at my grandparents’ house. I found it rather amazing that the hissing, buzzing bugs of the trees had originally emerged from the ground as such bizarre-looking creatures.
The sound the male imagos make is made by vibrating their intestinal membranes which shake noisemakers on the sides of their abdomen called timbals. Enlarged chambers in their tracheas act as resonance chambers. When the trees are covered in thousands of male imagos, the sound is amazingly loud. It is also unusually haunting, even a little bit beautiful. The male imagos sing these songs to attract mates.
Annual Cicadas singing:
After they mate, the female imago uses her ovipositor to put her eggs beneath the bark of a tree. She lays several hundred eggs, usually in several different trees.
Then the imagos die. They have passed on their genes to the next generation. When the eggs hatch, the newborn nymphs go to ground to live for two or three years. Then they will emerge and sing and mate and die, just as their parents did.
It is a strangely moving story of life and death. The cicadas spend most of their lives in darkness, only to arise for a few weeks in the sun where they sing and mate. And their little songs are summer’s recessional.
The annual cicada is not the only species of cicada that lives here. The most famous cicadas are the 17 year species (Magicicada). These live 17 years underground, and then emerge in early summer. Where I live, the batch for this particular type of cicada, is Batch V. When these cicadas emerge, they come out in vast numbers. It is something like a plague, which is why the folk name for cicadas in West Virginia is “locusts” (one of plagues from Exodus, although we all know locusts are actually large grasshoppers.) The last time this batch matured was in 1999, so the next time they will come above ground as imagos will be in 2016.
These cicadas make an entirely different sound.
Lots of things eat cicadas. They aren’t poisonous, and their main defense is simply to come out in vast numbers. In such large numbers, the predators can eat their fill and still some of the cicadas are able to reproduce.
However, where I live, the cicadas have to worry about a specific threat. We have a species of wasp called an Eastern cicada killer. As its name suggests, it hunts cicadas but not for its own consumption. These large wasps don’t actually kill the cicadas when they capture them. What happens is rather macabre.
Female cicada killers dig nests in the sand or loose clay, and then they go hunting. When they catch cicada, they sting it. Their stings paralyze the cicada, which the female wasp carries home alive to her nest.
She then places the cicada in her nest and lays an egg on it. She covers the nest. When the larvae hatch, they eat the cicada alive. Male eggs get one cicada to eat, but the females are given two or three. After two weeks eating the cicada, the larvae build a cocoon in which they overwinter. They hatch as mature wasps in the spring, and as adults, they live on nector and tree sap. But when mating season comes, the adult females become hunters.
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