is there a bug that lays white egg like things on the stems of mums?

Question

I had some aphids on my mums earlier in the summer and now the flowers are pretty, but the leaves underneath are all turning brown and I see these white things on most of the stems near the ground.

Answer 1

It sounds like you have aphids or mealy bugs. These articles will help:
https://www.gardeningknowhow.com/plant-problems/pests/mealybugs-white-residue-on-plants-leaves.htm
https://www.gardeningknowhow.com/plant-problems/pests/homemade-aphid-control-a-natural-way-to-kill-aphids.htm