Trees, Shrubs and Conifers: Red and white bull's eye type spots on a maple leaf, 1 by jugglerguy

jugglerguy wrote:
I just found several maple leaves on my lawn, so I looked up in the nearest maple looking for some sort of worm that might have cut them off. They weren't eaten and looked like normal, healthy leaves. They were cut off at the stem. I didn't see any obvious worms, but this leaf caught my eye. They have red and white spots with a small black dot in the center. They're bulging out toward the top of the leaf. It's almost like it got shot from underneath by a tiny shot gun. What the heck did this?