Wildlife Spotting

Using a different source, still looks like an orange sulfur. Orange Sulfur: http://bugguide.net/node/view/138493 Clouded Sulfur: http://bugguide.net/node/view/145979

It could be the lighting, but it looks like there is sufficient orange showing through the wing to suggest Orange Sulphur.

I deleted my suggestion as its non related specie...!!

@Kirsten With your reference Keith got it..!!

Southern dogface (zerene cesonia) has a much more southern range in North America. Dark Clouded Yellow (Colias croceus) is not found on the North American continent but is a similar looking species. Clouded Sulphur (Colias philodice) http://en.wikipedia.org/wiki/Colias_philodice and Orange Sulphur (Colias eurytheme) http://en.wikipedia.org/wiki/Orange_Sulphur are both likely candidates but it is hard to tell without looking at the upperside of the wing color.

Clouded Yellow (while a good visual match) should not be in the Americas. While the ranges of the other 2 could overlap, the wing shape identifies this as the orange orange sulfur.

http://en.wikipedia.org/wiki/Dark_Clouded_Yellow

Clouded Yellow.

Wing shape suggests Orange Sulphur.