Is your tree stressed? I have resolved this issue with a tree that i take care of by watering it extensively. A tulip tree in the middle of a textured concrete patio had a raised garden bed built around it. Always had an aphid problem. On year 3 of taking care of it i added soaker hoses around the base and run them as often as i can in the summer. The tree was never satisfying its thirst and was treated bad. So aphids were plenty. Perhaps your tree has a stressor to it inviting aphids.
Is your tree stressed? I have resolved this issue with a tree that i take care of by watering it extensively. A tulip tree in the middle of a textured concrete patio had a raised garden bed built around it. Always had an aphid problem. On year 3 of taking care of it i added soaker hoses around the base and run them as often as i can in the summer. The tree was never satisfying its thirst and was treated bad. So aphids were plenty. Perhaps your tree has a stressor to it inviting aphids.