I can't say I remember seeing this butterfly in a very long time, even though it is one of three native Whites found in the state of Wisconsin. In fact, I only remember seeing a few as a child while growing up in New Jersey! Thinking how very different they were from all the "other" white butterflies (later learning they were Cabbage Whites) I'd observed in the garden or chase around in the yard with friends, these certainly caught my attention!
Yet here they were, about a dozen of them flitting about with the beautiful and equally abundant Dainty Sulphurs in a friend's back yard early in September! Females are more heavily marked and look dirty or greyish compared to the pristine white of the males.
Left, female; Right, male
Host plants for the Checkered White caterpillars are cultivated and wild crucifers such as cauliflower, broccoli, turnip, cabbage, peppergrass, and shepherd's purse, to name a few.
Less destructive than the imported Cabbage White, I'd like to see more of these native butterflies around! --LKR