These uglies are on my maple's leaves. I've seen similar things before, but never given them much thought...But these are on *my* sapling! LOL. This little maple is a volunteer which sprouted in a flowerpot of ours in 1997. We faithfully potted it up every year in anticipation of planting it in the yard of our first home, which we bought in 1999. :o)
What are these little uglies and what can/should I do about them?