Leaves will sometimes shrivel and a gray dust occasionally forms on new leaf froth
This sounds like Downy Mildew; which can be common on Butterfly Bush.
This article will help you.
https://www.gardeningknowhow.com/ornamental/shrubs/butterfly-bush/butterfly-bush-diseases.htm
https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm
https://www.gardeningknowhow.com/garden-how-to/info/homemade-fungicide.htm
I know I have a big aphid issue but I also have at least a dozen little Monarch caterpillars feasting on it. So is there anything I can do? I am afraid if the leaves keep dying there won't be enough feed for the babies before cocoon time.
This is likely a watering issue; too much or too little.
This article will help you.
https://www.gardeningknowhow.com/ornamental/shrubs/butterfly-bush/butterfly-bush-container-care.htm
White & black caterpillars are eating my butterfly bush. What can I spray to keep them off and Away?
Here's a link with answers that will help you solve this problem: https://questions.gardeningknowhow.com/tag/butterfly-bushes/page/5/#catapilers
These are appearing just this morning on two different stems on my butterfly bush. Please do you know what these are and what do I need to do?? Thanks!!
Yes, these are Aphids.
Neem Oil is a safe way to treat your plants.
https://www.gardeningknowhow.com/plant-problems/pests/insects/homemade-aphid-control.htm
I do not have additional details and I do not have pictures
It typically takes about six weeks for a butterfly bush cutting to form roots.
https://www.gardeningknowhow.com/ornamental/shrubs/butterfly-bush/propagating-butterfly-bush.htm
Do we need to take faded flowers off of butterfly bushes?
It is a chore to deadhead butterfly bushes, but doing so will enhance the look of the shrub and prevent seeds from forming and dropping, producing weedy volunteers that invade native wetlands. Most bushes are hybrids and the seeds don't come back true. Ask for the sterile variety when purchasing butterfly bush.
Here is more information:
https://www.gardeningknowhow.com/ornamental/shrubs/butterfly-bush/butterfly-bush-care.htm
https://www.gardeningknowhow.com/ornamental/shrubs/butterfly-bush/butterfly-bush-pruning-how-to-prune-a-butterfly-bush.htm
Hi. I got a butterfly bush; it's in a pot which is about a foot and a half tall. Can I leave it outdoors in the pot over the winter? Will it survive my zone 6 winter in a pot? thanks
I have found some need winter protection to survive. For example, I wouldn't leave the pot outside unless it was heeled into the ground or wrapped in bubble wrap or burlap. You could leave it in the garage and water occasionally if you don't want to plant it now.
https://www.gardeningknowhow.com/ornamental/shrubs/butterfly-bush/butterfly-bush-care.htm