Preferably a three foot high (or a little taller) bench or location. Get your hose. Spray a forceful jet of water (not strong enough to remove leaves, but hard enough to push them up and move them around) UP into the foliage from below. Continue for several minutes. Repeat as necessary until aphids are washed away.
This works faster and less hazardously than any pesticide. Unless you have aphids caked on each shoot,it should control them adequately.
Combine this with Grants kills ants. Sprinkle the bait where the ants frequent at the base of the tree. They love the taste and will take the particles back to the queen. Your ant nest will be gone about the same time all the aphids die from a few applications of the neem oil.
I do not see ants around my tree. I live on the second floor of an apt building and my trees are on my balcony. I will look again for ants but they were not visible this morning. I will try the water technique and if that doesnt work, I have some Neem lying around that I will mix up. Any other techniques out there? Has anyone had bad luck with Neem on maples?