The Aphids created to food supply for the ants try —biological control
Aphids have many natural enemies, which include ladybeetles, syrphid fly larvae, and green lacewings. Avoid broad-spectrum insecticide applications that would disrupt these controls.
Management—cultural control
Home orchardists: Wash aphids from plants with a strong stream of water or by hand-wiping. Aphid populations tend to be higher in plants that are fertilized liberally with nitrogen. Avoid excessive watering which, together with nitrogen applications, produces flushes of succulent growth.

The aphids leave sugars on the leaves and twigs and the ants are manipulating them to keep up the work, introducing lady Beatles seldom works they just fly away. If you use a chemical remember that you will also kill the beneficial insects as well. We all have a threshold limit of damage that we can accept. Dormant spray can help prevent this problem.

Randy
Yamhill county master gardener

When there is a population explosion of one pest that goes beyond the 'balance', spot treatment is nothing to feel reluctant about. When small black ants were transporting green aphids up the tall twin trunks of a sour orange tree with satsuma grafted buds that were growing out, I used masking tape to make a sticky road block. After hosing off the suckers on the tender new leaves, I snuggly wrapped 2 spaced 'rings' of the tape with the sticky side facing outward. Many crawling critters became stuck before reaching the upper grafted area. One morning there were about 20 newly arrived ants on the tape, each one with a sqirming green aphid in it's jaws. Instead of doing the transporting randomly or once in a while, these came as a group. In retrospect, using 3/4" wide tape could be better, because sometimes anole lizards can get stuck, and it is easier to free them on narrow tape. When the glue is no longer sticky, remove and replace....until balance is restored. Maybe riot control officers would consider........