Phenotypic
plasticity, in the form of seasonal polyphenism in wing pattern,
is frequently expressed by multivoltine species with largely
non-overlapping generations of adults flying in the alternating
seasons.(4,5) For example, many species of temperate pierid
butterflies (the ‘‘whites’’) show seasonal variability in the
extent of wing melanization, with the butterflies that fly in
cooler periods of the year having larger black wing markings