iris has strange pest

I've got a 20 gallon pond in a lined barrel.
Somethings been chewing holes in my iris, and
in my water lily leaves. Kind of like someone
used a paper hole punch on them.

The iris also has a soft spot in the thick base
of one of the leaves, there's mush leaf stuff
and little black and green spheres (about 1/8 inch).
These don't appear to move or have legs, they look
more like seeds or eggs or something. I don't
see any flying or crawling bugs on the plants.

The pond is on a screened porch, and it's also
got goldfish. Everybody seems happy, though
the iris has overgrown its pot.

There's also some potted plants on the porch
which have some problems with mealy bugs, but
that doesn't seem related.

Does anybody recoginize this?

-malcolm