Question
I have read the answer given for the yellowing and withering of the butterfly bush offered by this site. It's just as I thought aphids. The suggestion was to spray with pesticide soap, this I also knew. What it failed to tell me is if I should remove all the infected leaves which seems standard procedure in most other plants with this same infestation. That has been my sole project this season is trying to keep up with aphid infestation from my vegtable gardens to my perenials. Other than do I remove infested leaves from my butterfly bush do you have any suggestions to slow this total infestation down, I have never seen it soo out of hand. It might help to know that I am located in Colorado and I really belive our past winter had somthing to do with it. I have seen other problems such as in the lawn directily related to this past winter.
Thank you, EH, Colorado

Answer
Sounds like the aphids have a good head start so I would try something else beside insecticidal soap. There is no need to pick the old leaves off if they die they will drop but most will live.
Insecticidal soaps are very good against aphids. As with summer oils, they apparently work to disrupt insect cell membranes. They require direct contact with the insects and leave no residual effect.



Nervous system insecticides, such as malathion, Dursban (chlorpyrifos), and Orthene (acephate), are labeled for use on many shade trees and ornamental plants for aphid control. As with oils and soaps, coverage is very important and a follow-up application may be necessary.
Acephate has systemic activity, which means it moves through leaves, thus it can be effective where aphids are hidden beneath curling foliage.
Check with your local nursery for a systemic insecticide for aphids.