Friday, 9 July 2010

BUTTERFLY: High Brown-, Dark Green- and Silver-washed Fritillaries in Cumbria

July 3-8, 2010
In south Cumbria, all three of the larger Fritillaries have now emerged. They are fast-flying, large orange butterflies which inhabit scrub and woodland clearings, especially over limestone, where their bright colouration makes them highly conspicuous. All of them rely on various species of violet for their larval food plant.

Three photos below: High Brown Fritillary:

Two photos below: Dark Green Fritillary:

Two photos below: Silver-washed Fritillary.

When seen in flight these three Fritillaries are difficult to distinguish from each other and even when viewed from above, if perched, they still appear very similar. However, a good view of the underside of the hind-wing makes matters simple. In this respect, the High Brown Fritillary has an additional row of brown, silver-centred, spots (ocelli) lying between the outer margin of the wing and the inner row of seven large silver spots. These ocelli are not present in either the Dark Green or the Silver-washed Fritillary. The High Brown Fritillary also has a brownish tinge to the underside of the hind-wing, whereas in the Dark Green Fritillary it is greenish; in the Silver-washed it is conspicuously silver-banded and almost unspotted.

The markings on the upper sides of the fore-wings also differ, but only slightly. In the High Brown Fritillary the third dark spot (from the wing tip) in the obvious line of spots set inward from the chevrons, is out of line with the previous two whereas in the Dark Green, all are in line. In the Silver-washed, whilst these spots are aligned, they tend to tail off into almost insignificance towards the wing tip. Additionally, the male Silver-washed Fritillary has four very prominent black veins of scent scales on the upper side of each fore-wing.

[High Brown Fritillary (both below), showing the additional ocelli on the under-side and the out-of-line third spot on the upper]

[Dark Green Fritillary (both below), showing the absence of ocelli on the underside and the in-line third spot on the upper]

[Silver-washed Fritillary (both below) showing the prominent silver bands on the under-side and the row of diminishing spots and the male's dark scent veins on the upper]

The High Brown Fritillary is now very scarce in this country with south Cumbria being one of its main strongholds

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