I had this exact problem with a mature Bloodgood Japanese Maple after some severe rains. Branches were lost but the tree survived. Make sure there are no external factors, like lawn applicants that could have affected the tree. Prune the tree back into shape and see how it grows this coming growing season.

Were your winter low temperatures considerably colder than usual? It does happen that plants suffer severe but hard to detect injury due to cold, leaf out and grow normally in the spring only to succumb over the summer. Late July and August are the months this most commonly becomes apparent. The fact that the bark is falling off is also typical of this phenomenon and is likely to happen with the maple as well as the elm. Sad to say, there is nothing you can do if the above is undeed the source of your difficulties.

Set it outside and saturate the soil 3x week, until water pours through the bottom.

It looks like scale, a sucking insect, but I can't see it clearly enough to determine what sort of scale. The ant is present because of honeydew, a sweet sticky substance that sucking insects excrete. If manageable, you can pick them off by hand. This is really the most efficient method of removal for small trees and shrubs but if heavily infested, it can take some time :-)) Otherwise, you must be able to identify the type of scale to pick the best treatment. Armored scale - like this appears to be - will only respond to insecticides if they are applied at the right stage of the insect's life cycle.