True Colors

This is the same butterfly as yesterday’s blip but without the overexposure so it’s true colors can be seen. Can anyone help me identify it? I thought it might be a Monarch as it is the season for Monarchs here but I don’t have any of the plants they typically like to eat and it doesn’t have the orange coloration apart from a small patch on the center right. Could it be one of the rare white ones, or perhaps this is just the underside of its wings?