Caterpillar foods: seeds of Goldenrod. This link from Bugguide explains their feeding and lifecycle.
I found these larvae in a jar where I had been adding pieces of Tall Goldenrod (Solidago altissima) to feed a different caterpillar. They may have come in as eggs on one of the goldenrod pieces, and hatched in the jar. There were several dozen larvae. They crawled around, dragging their cases with them, and settled in among the seeds in the flower clusters.
9/30/2021 Larva with its case. Click here to see a video.
9/30/2021 Several larvae with cases climbing out of the jar.
10/2/2021 Two larvae (in cases) in a cluster of goldenrod seeds
