This discussion has reminded me of something that happened to us a couple of years ago.

We planted 3 rows of plums in the middle of the orchard. The little trees were being choked by paspalum – an aggresive perennial grass. We sprayed this with glyphosate. Three weeks later these trees got smashed with aphids and loopers.

There was not an aphid to be seen on the trees around, that had not received any glyphosate.

It required 3 foliar nutrient sprays to clean those trees up. There have been no aphids since.