Pieris (Artogeia) mannii
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This butterfly is very
similar to the more
familiar and widespread small white. It is not, however, a pest of
domestic or commercial cabbages! In recent years it has been spreading
its range, perhaps due to acquiring a more eclectic taste in
foodplants. It is creeping northwards through France and in Switzerland
has moved up the mountains out of its strongholds in the Rhône Valley.
It is worth looking out for even as far north as southern England, just
in case this expansion continues unabated. Nevertheless, it remains -
and doubtless will remain - a much more local and specialised butterfly
than its cousin.
The most obvious difference between southern small white and small white is the dark apical tip of the forewing. In southern small white this extends down the outer margin at least as far as the top of the black discal mark. In small white it does not extend this far down and is noticeably longer along the costa than the outer margin. Another useful point of distinction is the underside of the hindwing, which is more evenly and densely scaled in southern small white. The wings of southern small white are also more rounded, though this character should not be relied upon. Finally, if a very good view of the underside is had, the present species lacks a fork in v.7 near the tip of the forewing.
Southern small whites appear
as early as
March in Switzerland, though usually slightly after the first small
whites. This may simply be a function of numbers - small whites are
commoner, so are more likely to be seen first just because they are
more likely to be seen at all. I have frequently seen the summer broods
up in the mountains, as high as 1200m, though I haven't seen the spring
broods up there. Like its cousins, this species spends the winter as a