Your insect is Oncopeltus fasciatus, the Greater Milkweed Bug. It feeds in milkweed (butterfly weed) plants, and prefers the flower buds and seed pods, which are rich in nutrients. In the course of feeding these bugs accumulate toxins from the milkweed. The bright colors warn predators of their toxicity.  These insects are a common sight on butterfly weed and should not cause severe damage to your plants. LW