Hello,

It would appear form your picture that you have a colony of ants that are tending the aphids so that they can harvest the honeydew that the aphids excrete. Read more here: https://www.canr.msu.edu/news/aphids_little_green_cows_of_the_bug_world

The easiest method of removing aphids is to hit them with a strong spray of water that will knock the aphids (and the ants) off the foliage. Once on the ground, they do not crawl back up the tree. Do not use a power washer because the spray may harm the plant. See other methods of removing aphids here: https://hgic.clemson.edu/factsheet/integrated-pest-management-i-p-m-for-aphids/

Remember, if using a pesticide, read the label to ensure that it will be effective against aphids and follow the instructions on when and how to apply the pesticide.

Thank you for contacting Ask Extension.