huge yellow?

[tana]

Hi, I'm so glad I found your group, I'm a newbie to Lep and need help
identifying a massive yellow butterfly I saw last week. His wings were very
bright yellow with tiny spots, unfortunately it was too quick and erratic to
see what pattern the spots made or what colour they were (dark). It may have
been 4 inches or so horizontally. I live in Kingston, Ont. by the lake and
have many plants/shrubs all over the property including native plants. It
came to my pebble bird feeder.
Was this just a genetic oddball or do they come that big here?
Thanks in advance for any help offered.
Tana