This was something I came up with due to OldDog’s pestering ;-)
Hope you enjoy…

Crawling, sniffing, pausing, launching
To furiously circle and crash face-forward
Again and again.

I can see the sun
I cannot see a barrier
Though I inspect its surface.

All else is dark-
That way is light;
The faintest leak of air
Tells me “that way is home”.

So I flail and beat
Against that which I cannot see-
Untill finally I rise no more
My curled dry husk gathering dust
With the others,

The brittle dry corpses
Of the windowsill.