With patience, we have the final answer about the milkweed bugs.
Checking the plant, there are some newly-molted adults.
The new adults are lack the dark pigmentation. This one is adjusting its wings with its back feet.
As they darken more, it becomes clear that they are indeed small milkweed bugs, Lygaeus kalmii.
Having spent so much time watching them, they seem like old friends.
Now I will be on the look out for eggs!
Have you ever observed insects in nature over a period of weeks? What kind of insect was it?