By autumn, the swelled galls with be more noticeable on the dried thinner stems. The larvae will stay in the gall through winter, unless a bird pecks through to feast on them. In Spring, those who stay hidden will emerge as adults.
The most typical insect causing galls are the Goldenrod Gall Flies Eurosta solidagnis, who completes its entire life cycle only on goldenrod.
Last fall, I gathered several dried stems with galls. They are such interesting shapes and colors, so they deserved to be in a drawing or painting!
