Walking in the park near
twilight in these early days of Spring, when the shadows stretch deeply onto
the far bank of the pond, it is difficult to miss the odd humming sound in the
air.
The unmistakable murmur
of cicadas in the midst of their mating ritual, the droning buzz rushes out
across the surface of the water like a swarm of bees passing through a hollow
log.
It is an evocative music,
the cicada song. For the wanderer in the park, it recalls magical nights of summers
long past, and the hidden joy of sudden encounters with the living presence of
nature in the midst of a warm summer's evening.
In the case of the
insects themselves, however, the humming represents the soundtrack of a brief,
remarkable cycle of life that bespeaks both the wisdom and the wonder of
nature's strange logic.
While "annual"
varieties of cicadas appear every year, the particular insects now in the park
are most probably of the Magicicada genus — the so-called
"periodical" cicadas.
These cicadas live
underground for a period of 13 or 17 years, and then emerge in
massive numbers for a brief mating period before they die, leaving their
progeny to begin again the long cycle of nurture underground.
The sound of the cicada's
song is produced by the rapid vibration of membranes on the insect's abdomen.
The vibration of the membranes, which are properly known as tymbals, produces a
chirping that is then amplified by chambers within the creature's respiratory
system. Male cicadas "sing" the song in large choruses to attract
females.
In accordance with the
science of the identification system devised by entomologist C. L. Marlatt in
1907, the insects in the park are most likely Brood II cicadas, of the 17-year
variety.
It is the poetry of their
appearance, however, that leaves a lasting impression. After 17 years
underground — a period in which the human world routinely sees the utter
transformation of leading personalities and technologies and societies — these
tiny creatures struggle upward through a foot or more of soil to emerge, all at
once, in the still-chilly air of the early hintings of summer.
They spend their brief
time on the surface in the pursuit of a mate, in the interest of ensuring the
propagation of their species. Then, after a period of several weeks to several
months, their course is run, and their song withers to the last few chirrups of
those who remain at the end, like the sound of a valiant heart drumming its
last in the moments before death.
As all falls silent, the
purpose of the cicadas' brief time on the surface is accomplished in the
production and hatching of their eggs, ensuring the promise of a new
generation.
The newborn nymphs fall
like raindrops from the twigs where the eggs were laid, and upon landing on
grass or soil, they burrow downward, to begin another long cycle of life
underground.
Meanwhile, their song
sung, the adult cicadas die off. The tone and timbre of their particular sound
vanishes once more from the landscape, hidden away in the dust of the Earth and
the promise of their descendants, not to be heard again until the first chilly
days of Spring, 17 years on...
© Patrick J. Walsh
No comments:
Post a Comment