Aphids exist just fine without the aid of ants. Never assume that ants are responsible for the presence of aphids, okay?

I can barely see the green insects, but know that they are aphids because the larger brown ones are what are called 'aphid mummies '. Those are the dead, swollen bodies of aphids which have been parasitized by the larvae of tiny wasps, a beneficial parasitoid.

I don't see an exit hole in the body of the mummy, which means that the parasitoid is still growing in there....there will be a visible hole when it has exited as an adult teensy wasp.

I wouldn't do anything but squish the green ones, leaving the mummies to help populate the area with more of those beneficials.