It's going to be challenging to get rid of them in your case. Make sure you have aphids first. Once you verify they're aphids, try getting a hose attachment that you can add a treatment to, such as 2 tsp dawn soap + 1 cup isopropyl alcohol + 3 cups water (increase amounts in those proportions.) If you're in drought or water shortage, you can also try running misting tubes (usually meant for watering at ground level) up the trees and, again, use that mixture -- you might be better able to cover a larger area that will stick to the trees by misting them. Anything you can do to coat the trees and make them uninhabitable to aphids will help. Fortunately, we live in a creative time of ingenuity. You might even be able to find some sort of misting contraption (like they have for mosquitoes) that emits something that aphids don't like, and hang that in your trees. You'd be surprised what you can find if only you look around. After that, see if you can get some ladybugs - release them at sundown in your trees, right on top of the aphids if you can. Ladybugs are safe and good bugs, but don't put them on your trees before spraying or dusting them.
It's going to be challenging to get rid of them in your case. Make sure you have aphids first. Once you verify they're aphids, try getting a hose attachment that you can add a treatment to, such as 2 tsp dawn soap + 1 cup isopropyl alcohol + 3 cups water (increase amounts in those proportions.) If you're in drought or water shortage, you can also try running misting tubes (usually meant for watering at ground level) up the trees and, again, use that mixture -- you might be better able to cover a larger area that will stick to the trees by misting them. Anything you can do to coat the trees and make them uninhabitable to aphids will help. Fortunately, we live in a creative time of ingenuity. You might even be able to find some sort of misting contraption (like they have for mosquitoes) that emits something that aphids don't like, and hang that in your trees. You'd be surprised what you can find if only you look around. After that, see if you can get some ladybugs - release them at sundown in your trees, right on top of the aphids if you can. Ladybugs are safe and good bugs, but don't put them on your trees before spraying or dusting them.