Pearl-bordered
Fritillary (Boloria euphrosyne)
This beautiful woodland butterfly occurs in
scattered and isolated colonies south-west of a line running between
Denbighshire in the north-west to East Kent in the in south-east. There are
also colonies in Westmorland and West Lancashire. It is also widespread in
central Scotland, but very local or absent in the north and south of the
country. In Ireland, it is found in the Burren limestones of Clare and southeast
Galway. It is absent from the western and northern Isles of Scotland, the Isle
of Man and the Channel Islands. B. euphrosyne survives in West Sussex thanks to carefully managed Sweet
Chestnut coppice in several important woodlands which allows the Common Dog-violet (Viola riviniana), the main larval foodplant, to grow in appropriate conditions.
This is the earliest of our fritillaries to
emerge. In good years, the butterfly emerges at the end of April in the south.
Most adults emerge at the start of May, but may not appear until the end of May
in more northerly locations.
B. euphrosyne is typically
found in deciduous woodland containing open areas, such as woodland clearings,
that provide the right conditions, foodplants and nectar sources for this
species to survive. Suitable sites are generally habitable 2 to 4 years after a woodland
clearing has been formed, when the foodplants and nectar sources are optimal
for this species. However, these sites can quickly become overgrown and, unless
there is suitable habitat nearby or regular habitat management undertaken, colonies are often lost.
Larvae feed by day and generally rest in leaf litter,
but can also be found, especially after hibernation, basking on dead bracken.
They eat the entire leaves, leaving just the stem intact. They will also feed
on only the leaf lobes, at the base of the leaf, leaving characteristic feeding
damage that can give away the presence of a nearby larva. After moulting for
the third time the larva enters hibernation, generally in a dried leaf,
emerging in the spring to complete its growth. There are 4 moults in total.
The two images
show a male, referable to ab. interligata, Cabeau (1919) + ab. transversa,
Vorbrodt (1911) recently found in West Sussex.
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