While hiking the Sugarloaf Trail, Tammy and I kept getting tricked into thinking it was about to rain. The occasional clouds that obscured the sun, and being under the canopy of trees, caused the light to sometimes dim as if rain clouds were rolling in. And then we would notice the sound of what we thought were raindrops falling through the trees. But then the sun would come back out, and that sound of raindrops would persist. And we never felt a single raindrop.
So we focused on that sound and decided that it was like a really, really slow rain. Almost like the rain on the very edge of a storm. Since nothing was wet and it was really more sunny than cloudy, we knew it could not be rain. But that sound of something falling through the leaves was always there.
When we later stopped to examine some caterpillars on the side of the trail, we finally put two and two together. There were lots of caterpillars. At first, I was assuming these were Eastern Tent Caterpillars, but after some searching on Google, a bit of reading (here and here) and some picture comparisons, I have decided that these were Gypsy Moth Caterpillars. The Gypsy Moth is an introduced species in North America. We have Étienne Léopold Trouvelot, and his fleeting interest in entomology, to thank for this.
The caterpillars were happily munching on leaves. Everywhere you looked you saw caterpillars on leaves, and the leaves had holes in them or giant chunks missing from them. And when you examined the trail closely, you noticed bits of green leaves everywhere. Our conclusion was that the massive number of Gypsy Moth Caterpillars were chowing down on the leaves in the canopy, and an endless stream of leaf pieces were falling down to the ground.