Until recent years this butterfly was usually
referred to as Sara's Orange-tip, with minor variations with the hyphen and
apostrophe and in the spelling of Anthocharis, although I have also seen
the name Western Orange Tip. It has recently been recognized that there are
two distinct species of Anthocharis in Canada, the one of Vancouver Island
being sara. Because A. stella was formerly lumped in with "Sara's
Orange-tip" it is probably better to drop that name altogether now, and
the name "Pacific Orangetip" has been proposed. It may be best to
stick to the scientific name.
The orange patch at the wingtip of the adult female is not as deeply coloured as that of the male, and it is separated from the black at the extreme tip by a small whitish gap. The difference can be seen in the photographs. On southern Vancouver Island, the preferred foodplant is Arabis glabra, but I have also found caterpillars on Lepidium montanum and they will also accept Cardamine oligosperma. I would expect that they would also like C. pulcherrima, but they seem not to like cultivated garden varieties of "Arabis". The pupa is green to begin with, but as fall and winter advances, vegetation changes to straw-coloured and even black as it decays. The colour of the pupa follows suit.
This butterfly is one of the first to appear in the spring (apart from those nymphalids that overwinter in the adult state), and, until recent years, could easily be described as common. Since 2000 it has become quite uncommon in the area and I am not optimistic that this is merely a temporary fluctuation from which it will recover.