The poplar admiral is a
magnificent - and
in most of Europe, rare - butterfly. The female especially is huge,
though even the male is substantially bigger than a purple emperor, and
both sexes have a flight so powerful they can be up in the canopy and
across the glade before you can whisper their name. This is essentially
an insect of forests, though I havetwice seen it hilltopping above the
treeline. It is also strangely elusive. I have mostly come across
individuals by chance, and the one year (2015) when I saw 12 or more on
the same day in a set of woodland rides near Geneva remains to date
(2020) the last year I saw them at all, despite many subsequent
searches in the same rides. I see males more than females, perhaps
because males more readily come to dung and minerals along tracks.
Males are a deep brown
above with orange
and blue trimmings around the edges of the wings and varying amounts of
white in the form of spots and bands. Typically, there is a tapering
band on the hindwing, a large spot at the end of the cell on the
forewing and two irregular rows of spots outside this. However, some or
all of these white marks may be missing. The darkest individuals are
known as form tremulae
but
any amount of white between the two extremes is possible. Females are
similar but bigger and with stronger white markings. The band on the
hindwing is broader. Both sexes are orange beneath with a pattern
similar to that of the much commoner white admiral.
The foodplant is aspen. In Switzerland, adults are on the wing from the
end of May, though individuals are short-lived and if they emerge
together the season may be short. I have seen them in July in the
mountains. Caterpillars are said to make leaf extensions, rather like
white admirals, and also like them hibernate on branches or twigs in
hibernaculae.
