Colias

[Michael Philip]

Hello,

    The weather was beautiful here in Raleigh today, and the Colias
butterflies were out and about.  Seeing butterflies in February helped quell
my homesickness for Michigan.  Anyway, I have a question about these little
guys maybe someone can help me out with.
    The Colias butterflies I saw today were males of either philodice or
eurytheme.  They are very small, like I would expect the early ones to be,
and are yellow with basal orange coloring.  Opler's Butterflies East of the
G.P. indicates that these are spring forms of eurytheme.  This makes perfect
sense down here considering the fact that it is February and eurytheme is
more common than philodice around these parts.
    However, back home in Michigan, this form is common in places where
philodice is much, much more common than eurytheme.  I have collected this
form in May and July, and the 'normal' orange form in June.  Both forms are
roughly the same size.  It doesn't seem to make sense in terms of
photoperiods.
    Anyone know what's going on here?  Why have I collected full-sized
'spring' forms in late July?

Thanks.

Mike Philip
Raleigh, N. Carolina