Before you do what I'm about to say, check to see how your maple would react to it!!!!
I've gotten mealy bugs off my fukien by spraying isopropyl alcohol all over the tree, letting it sit for a few seconds, and then rinsing it off completely. Check a week later and dab any remaining bugs off with a q-tip dipped in alcohol. I then rinsed the tree afterwards to get rid of any remaining alcohol.
Again, check on what would be best for your species of tree!!!