Hello Donna

Fortunately, there is no real threat or damage to your tree. The insects caused leaf galls to form on your leaves. This could be the Maple bladder gall, especially if it reddens as the galls mature.

Now that the galls are present there is no action you should take, other than perhaps raking up leaves as they fall and disposing of them. Keep your tree well watered if we experience a drought this summer or fall( more than 2 weeks with no expected rainfall).

If we have a more severe winter this coming season it will reduce the number of insects that cause leaf galls.

Here are some Extension bulletins about leaf galls.

https://ohioline.osu.edu/factsheet/ENT-60

https://www.canr.msu.edu/news/what_are_these_ugly_bumps_on_my_trees_leaves