You could move the larve but there is no way to move all the aphids that they need, I suggest you leave them and just go with fewwer flowers next year, the reduction in aphid population will help all of your plants to bloom next year, negating the effect of fewwer spirea bFlowers, You can however prune out the branches with no larve on them.

Yea, I was thinking about pruning out the branches without any aphids and larve but that would take forever. I guess I'll just leave them for now and see how long they stick around for. I could look for other plants in my garden that have aphids and transfer them to those plants. Hopefully they will eat all the aphids soon and be done with it, but I doubt it.