Susan –
Aphids — a soft-bodied pest — are relatively easy to control using natural controls… the problem is they reproduce quickly! I recommend spot-treating with something short-lived in the environment (Insecticidal Soap, Diatomaceous Earth, etc) to provide a quick knockdown when necessary. This will also reduce the chances of your “good bugs” being harmed that are out there working to keep the pest population in check. Here’s a couple of links that will help!
https://www.planetnatural.com/pest-problem-solver/lawn-pests/aphid-control/
https://www.planetnatural.com/organic-control-aphids/
“When we kill off the natural enemies of a pest, we inherit their work.” – C.B Huffaker