The sound is so persistent that it fades from consciousness, but if you're near a window as you read this, listen.
At most times of day and even more so at night the insects are out, creating a delicate sound screen of late summer chirps, whirrs, and songs. These sounds signal that we're now in the transitional season; one foot still in summer, the other raised to enter into fall.
What are these creatures, and why are they compelled to incessantly make noise, especially at night?
I had vaguely imagined that these insects created sounds to find mates, and this turns out to be vaguely the case. The most loquacious insects in our area are cicadas, katydids, and crickets, and it's only the males that are the noisemakers. Lacking vocal cords, insects can't make sound with their mouths. Wings, legs, or other body parts vibrating or rubbing against one another generate the noise itself.
The cacophony is meant to announce the males' presence to females, who are willing to travel great distances in search of a mate. The risk of nuptial travel is greater during the day, when more predators are on the prowl, and so these calling insects often pursue most of their courtship in the cover of night.
The mating begins in mid-to late summer, and continues into the fall, depending on the species. Eggs are laid on tree branches (cicadas and katydids) or in the ground (crickets) where they overwinter before hatching in the spring.
The adults will not be so lucky to see another season. As the days grow shorter and the nights grow cooler, their songs grow slower, and become fainter as more of their population has finished their natural lifespan. By the time crisp October weather rolls around, there will be a day I stop and listen, and hear nothing.
Enjoy the sounds of summer while you can.