leaves that fell into a stream.
I'm amazed how the small silk nets can stand there given the strong currents where they are erected. Wouldn't it be fun to watch a caddisfly larva spin its underwater web and erect those guyed poles?
The larvae are not very pretty, but are well designed for their unique lifestyle.
In the photo below a caddisfly larva is tending its net (on the left).
Here's a view looking straight down on a falls where the caddisfly larvae have spun their silk nets right on the very edge. Interestingly, in this photo you can also see some caddisfly larvae tending their nets.
Whenever I would place my underwater digital camera near enough to snap a close-up photo of the larvae they would back into the depths of their silk retreats.
Personally, I think the silk nets add to the underwater scenery.
Incidentally, cities are often built at "falls".
What lives in a waterfall?"
I doubt they'll forget the crowds of silk nets at the falls and in the swift water.
See What Lives In a Waterfall? Part I
Also see What Lives In a Waterfall? Part II
I make reference to these caddisfly larvae nets in "Under The Susquehanna".
Here is another underwater photo of the caddisfly nets.