Sunday, July 18, 2010

Silver-washed Fritillary/Kejserkåbe

Argynnis paphia

Silver-washed Fritillary
Bjerre Skov, Horsens, Jutland

The Silver-washed Fritillary is active right now in July until late August, and each year I go to Bjerre forest by Vejle fjord to look for it. It flies in glades and sunny spots of the wood and loves the blackberry flowers. The Danish name Kejserkåbe means Emperor's Cape and this fine coloured pattern would certainly be a beautiful cape for an emperor. The Silver-washed fritillary lives in Europe except southern Spain, Scotland and the northern part of Scandinavia.

The Silver-washed fritillary butterfly is deep orange with black spots on the upper side of its wings and has a wingspan of 54–70 mm, with the male being smaller and paler than the female. The underside is green and unlike other fritillaries has silver streaks instead of silver spots, hence the name silver-washed. A rare variation in some years is a special female, which is green-black with a straw coloured base.

Unusually for a butterfly, the female does not lay her eggs on the leaves or stem of the caterpillar's food source (in this case violets) but instead one or two meters above the woodland floor in the crevices of tree bark close to clumps of violets. The larvae's fodder plants are various Violas.

The Silver-washed Fritillary is a strong flier and more mobile than other fritillaries and as such can be seen gliding above the tree canopy at high speed. Its flight is safe, fast and sailing and it seeks especially to flowers of blackberry and thistles. The mating dance, which can be watched on good localities in the morning, is very characteristic and beautiful. The male flies down under and then steep up in front of the female, who continues to fly straight on, while the male lose speed and once again dives down under and steep up in front of the female.

In Denmark Argynnis pahia is still common at Lolland-Falster, Møns Klint, Sydsjælland and Bornholm, but has during the 1970s and 1980s declined much in Jutland, at Funen, West- and North Sjælland.

Protection of the species:
This species needs many small and unfertilized glades. It thrives well in forests with extensive utilization, like in stævningsskove, (coppicing) which hold many glades in various growth. The Silver-washed Fritillary (Argynnis paphia) is on the Danish Red List as moderately endangered.

In the old days the Silver-washed Fritillary was especially connected to the stævningsskove (Coppicing woods). It is in a serious decline in Denmark, possibly caused by the lack of light-open varied forests. Until ab. 1990 it was numerous in North Jutland in Rold Skov and in Lille Vildmose, but after 1990 it is only known in a few examples, i.e. Rebild, and outside North Jutland in the forests by Vejle fjord, in Gudbjerg skov at Funen and Gribskov in North Sjælland. Still numerous populations in the rest of Sjælland, on the southern islands and Bornholm.

photo Bjerre Skov 17. July 2010: grethe bachmann


Teresa Evangeline said...

I wonder if their decline is a natural cycle in nature, or part of what appears to be a changing world, environmentally speaking...

Thyra said...

Hello Teresa Evangelina! I'm not sure if we've got much influence on the climate changes. There were always changes of climate.
I'm especially interested in the insects because I can see the difference when I'm out in the country. The insects and especially the butterflies are fragile to changes. Just one thing: In this country the farmers have for many years had obligatory set-aside fields which mean a richer bio-diversity. But then they were suddenly allowed to cultivate those fields. This means that the distance between the good habitats grows longer and thereby too far away for some insects and butterflies, and some species disappear never to come back. Most of the farmers cultivated the set-aside fields and they ploughed the rest not to miss the deadline. I have seen those fields. Some of them are now planted with "Christmas trees". It makes me feel sick.
Thank you for your interest.

Teresa Evangeline said...

Thank You for your further insight!