Oh, that makes a lot of sense. My Norway maples get huge brown circular blotches in the late summer. Thanks for replying so fast!

Those brown blotches on Norway maples are caused by a fungus. Phyllonorycter leaf mines look like this:

Most native leafminers don't use Norway maple, but this species does sometimes use it.

So the insect called the maple leaf blotch miner doesn't cause the big blotches on my Norway maples - why is it called "blotch miner"? Just curious. Thanks for straightening me out again and again. :-)

When people come up with common names for whole families of insects, there are often species that don't really fit the names. Someone decided that the name "leaf blotch miner" should be applied to all of the hundreds of moths in the family Gracillariidae, many of which definitely do make blotch mines:

Others clearly don't fit this description at all:

I steer clear of common names for leafminers, partly because of this problem and partly because there are (for instance) at least ten different gracillariids that mine in maple leaves, and I don't see why any one of them should get to be "the" maple leaf blotch miner.

Thanks. So some mines are blotchy and others are more traditional tracks - That really helps. I've been a bugophile all my life but now find myself learning and unlearning so much! Thanks again!