Explanation of Names
Colias eurytheme Boisduval, 1852
Similar to C. philodice
; generally larger; orange instead of yellow (most noticeable on upper surface), and wider dark wing margins.(1)
. C. eurytheme
is also less likely to have grayish scaling on the lower surface and tends to have broader wings with slightly more angular shapes.
The white form females of the two species are the same color, but those of eurytheme can often be separated from the white form female philodice by the narrower dark HW outer border. In philodice the HW border will usually not have any pale spots included, while eurytheme most often has included spots that are often isolated from the rest of the wing. This is variable in both species, but is often a helpful "rule of thumb".
Example white-form female lacking any orange:
CA-FL-ME-BC / Mex., Cuba - MPG
not as far north as C. philodice
flies to Dec. in many states - MPG
It overwinters as larva or pupa
Larvae feed on alfalfa, clover, and other legumes.(1)