The large milkweed bug is roughly half an inch long as a adult, Daisy, but the nymphs would vary from tiny upwards and they look different. This Bugguide picture shows both adults and nymphs:
http://bugguide.net/node/view/...
There's also a small milkweed bug, Lygaeus kalmii, there's a good picture of one on the American Hemerocallis Society's web site, the bottom image. They usually have two white spots on their rear ends and the black and red pattern is slightly different from the large milkweed bug and it may be a little smaller:
http://www.daylilies.org/ahs_d...
Again the nymphs would vary from tiny upwards as they go through their growth stages, and would look different, like this:
https://www.google.ca/search?q...
These are "true bugs", but there are also a couple of red and black beetles that hang out on milkweed so if it doesn't look like either of the bugs above then that's another possibility. I mostly see the small milkweed bug around here.
Sandy, both large and small milkweed bugs occur in Michigan, here's a pic of the large one taken there:
http://bugguide.net/node/view/...
