The Western White is a stray from the west that has only been reported once in Wisconsin.
Weekly sightings for Western White
White butterfly with extensive black or brown markings. The female has much more extensive markings. Like the Mustard White, this species has a spring form that has dark, greenish veins beneath.
The Checkered White may be mistaken for a male Western White; look at the front wing marginal spots above. If there are 5-6 spots and these spots are much darker than the outer spots then it is could be a Western White; the Checkered White has only 2-3 of these spots.