Meet the Small Milkweed Bug (Lygaeus kalmii).
This little fellow is mostly harmless, unless you are a milkweed breeder. Its favorite food are milkweed seeds, but it won't be too picky about other seeds or sources of protein. In a balanced garden, they allow you to have milkweed for the butterflies without being overrun by it as weeds. (They will eat the occasional butterfly egg though, but also other insects.)
They are completely harmless for humans and only if you feel they are a nuisance or you can't tolerate the minimal feeding damage some intervention may be warranted - manually removing large clusters should suffice.
More links: 1, 2, Wikipedia (available only in German, not English)