Hi.

I've got a 1/2 barrel pond with a plastic liner on my porch.
There are some tiny bugs that hang out on the walls of the
liner just above the water line. If disturbed, they jump
onto the surface of the water, where they float and then
return to the side. They can jump several inches. They're
smaller than a grain of salt and look sort of redish brown.

Can someone tell me what these are and if they are something
I should try to control, or just leave alone? Thanks.

-malcolm