Hello,

That is a Clavate tortoise beetle, Plagiometriona clavata (Coleoptera: Chrysomelidae).

These tortoise beetles are small (5/16 of an inch), oval, "turtle-shaped" beetle.  Tortoise beetles have the sides of the body flared giving the beetle the overall shape of a World War I U.S. infantry helmet.  The larvae or grubs are even more bizarre in appearance and habits. They are elongate-oval, somewhat flattened, and are quite spiny.  When mature, they are about 3/8” long.  The spines are thorny and somewhat branched. . The larvae are unique in that they accumulate their excrement, cast skins, and other "trash" on their backs.  Once loaded with trash, the "tail" is curled up over the back, which helps to protect the grub from predators.
 
Tortoise beetles are leaf feeders in both the adult and larval stages. Several species are occasional pests of soybeans in other parts of the U.S.  In the Northeast, tortoise beetles are occasional minor pests on potatoes and morning glories grown as ornamental flowers.  Many species of tortoise beetles are beneficial insects in that they feed on bindweed, thistle, burdock, and other weeds. Tortoise beetles overwinter in the adult stage, hiding themselves in dry sheltered places under bark or trash.  The adults emerge in mid- to late May.  Eggs are laid either singly or in clusters of 20 to 30 directly on the host plant.  The larvae begin feeding as soon as they hatch. There appears to be one generation per year in Michigan.
 
Tortoise beetles rarely need to be controlled, but if they do appear in damaging numbers, then an insecticide labeled for the particular will prevent further damage.  Sevin Garden Dust, Ortho Bug-B-Gon (bifenthrin) and Bayer Advanced Vegetable and Garden Spray (cyfluthrin) should be very effective in controlling this beetle. Be sure to read the label before using.