"Coliadinae, the sulphurs or yellows, are a subfamily of butterflies with about 300 described species.
There are 36 species in North America, where they range from Mexico ...
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to northern Canada. In most species, males are easily distinguished from females. For example, in the genera Colias and Gonepteryx), males exhibit brilliant UV reflections that the females lack." - (en.wikipedia.org 09.01.2021)