TreeSpecialist

My first thought,because you were in Canada and the problem looked close to a driveway, was a problem with salt.

However, the close up of the leaves show a puncture mark in the petiole and your diagnosis of the a maple petiole borer (Caulocampus acericaulis - a type of sawfly) is likely correct.

Tough to control without the use of a systemic insecticide. (Imidicloprid, Abamectin, etc.) Timing of an injectable would be crucial as well to do any good.

Raking and disposing of the leaves, while on the surface sounds like a good way to minimize re-infestation, doesn't work all that well as the larva doing the damage remains in the tree.

Getting an insecticide in or on the tree at the right moment is close to impossible. Since the larva eventually falls to the ground and spends the rest of the year there before emerging as an adult the following spring to repeat the cycle, you might want to try something else.

An "organic" method of controlling ground dwelling larva of various types is to introduce milky spore bacteria (Bacillus popilliae) into the yard.

Beneficial nematodes are another tack to consider. While I'm uncertain as to which of the beneficials to use (Heterorhabditis bacteriophora, Steinernema carpocapse, Steinernema feltiae), nematodes may be an excellent way of minimizing future infestations.

You might want to collect some of the petiole stubs left in the tree and allow the larvae to grow out in a collection jar. You'd have a better chance of identifying the pest that way.

Good luck.