Yay! I love seeing butterflies from different areas. I'm assuming that Great Arctic is a type of Fritillary. I've also seen moths that look like yours here. May be a cousin or something. Let us know when you get an ID. And you get Cabbage Whites in Canada? I love butterflies, but I hate invasive species so I'm terribly conflicted on them. I wish they'd never been introduced but how do you get rid of them without harming other species? Very tough problem. I know in my WV butterfly book there is a species called a West Virginia White and the book says the Cabbage Whites are out-competing them. There's also a Florida White but it lives way down south in the state. Luckily, it has different host plants than the other whites. I've only ever seen one Cabbage White here in my section of Florida; maybe it's just too hot for them?
