This name or label is the closest match found in online searches with the scientific name of Ganyra josephina, found from South Texas all the way through Central America to northern South America. It is similar to the Felder’s White found in the book A Swift Guide to the Butterflies of Mexico and Central America with scientific name Ganyra phaloe (which name I almost gave it). Another web page had a similar butterfly labeled Godart’s White, almost identical to Felder’s, both having a little brown edge around the upper wings which mine does not have. Mine more closely matches the “Giant White” photos and descriptions online but is not in Swift’s book.
Butterflies are so difficult to identify, especially in Costa Rica where we seem to have millions of different ones! This was photographed in my garden in Atenas, Costa Rica.
See also my Photo Gallery Butterflies and Moths with more than 70 species photographed here in Costa Rica.
I also have a little 7X7 inch photo book titled My First 50 Butterflies in Costa Rica. You can preview all pages electronically for free at this link. Best viewed full screen for bigger photos.