A month ago, I planted three healthy looking store-bought evening primrose plants. They have been doing fine, especially after I mulched the area (they are on a slope). However, this morning I noticed some white fuzzy stuff on the stems of each of the plants. I saw a small white moth and lots of tiny white little things that jumped all over as I sprayed the plant with insecticide. I Googled a bit on primrose+pest but the diseases/insects listed don't look anything like what I'm trying to describe here.

Anybody have any idea what this is? I think I've seen the same white fuzzy stuff on some wild plants around this area. I am in zone 5 and it's been very dark, damp and cool all July.

Thanks in advance.