Last week at a site in Lake County, Indiana, Tony Troche and I observed a very interesting caterpillar climbing on a stem of Flat-topped Aster (Aster umbellatus). I actually thought that the caterpillar was moving up the stem, but in fact, it is moving down. The humped eighth abdominal segment is one of the identifying characters for this colorful caterpillar.
This is the larval stage of a Brown-hooded Owlet (Cucullia convexipennis), also known as the Brown-bordered Owlet and the Brown-bordered Cucullia. An excellent description of this caterpillar can be found in Caterpillars of Eastern North America: "Each individual appears as if it were hand-painted and then glazed." Brown-hooded Owlets are found from Nova Scotia south to Georgia, and west to Minnesota and Missouri. Host plants for this species include asters (Aster spp.) and goldenrods (Solidago spp.).
A photo and description of the Brown-hooded Owlet moth can be found at nearctica.com.