The Pearl-bordered Fritillary (Argynnis Euphrosyne)
Some authors consider the smaller Fritillaries to be generically separable from the larger kinds, and place this and the next species in the genus Brenthis, whilst the Queen of Spain is referred to the genus Issoria, Hübner. Here, however, they are retained in Argynnis.
In colour and in the marking of the upper side the Pearl-bordered is very like the High Brown, but, as will be seen from the figures, it is much smaller in size, and the ornamentation on the under side is different. There is one silvery spot at the base of the hind wings, a larger one about the middle of the wings, and a row of spots on the outer margin. The female is rather larger than the male, and darker at the bases of the wings.
Variation on the upper side consists of more or less black suffusion on the basal or general area of the wings, and an increase in the size of the black spots, resulting in the formation of bands or patches; or the black spots may be much reduced in size, and some of them entirely absent. Some of the more striking kinds of aberration, both above and below, are represented on Plate 56, Figs. 1-3, and Plate 65, Figs. 1-4. The usual colour is sometimes replaced by buff, and this may be yellowish or whitish in tint; occasionally white spots appear on the wings. The life-history of this butterfly is depicted on Plate 60.
The egg, which is laid in May or June, is whitish-green at first, and afterwards turns brownish. It is distinctly ribbed, and the top is somewhat rounded and hollowed in the centre.
The full-grown caterpillar is black, and the numerous minute hairs with which it is clothed give it a velvety appearance. There is a greyish-edged black line down the middle of the back, and the spines on each side of this are whitish or yellowish, with the tips and the branches black; all the other spines are black. A greyish stripe runs along the lower part of the sides, and this is traversed from the fourth to the last ring by a blackish line. Head black, shining, downy, and slightly notched on the crown. The natural food-plant is dog-violet (Viola canina), but the caterpillar will also eat garden pansy, and has been known to nibble a leaf of primrose. It retires for hibernation when quite small, and recommences to feed in March.
The chrysalis is brownish, with the raised parts of the thorax and head greyish; the body is paler brown, and the points thereon are blackish.
This butterfly seems to be fairly common in woods throughout England and Wales, and it is often abundant in some of the more extensive woodlands, especially in the southern counties. It used to be plentiful in Northumberland and Durham, but has become scarcer in those counties, and in some others in the north of England. It occurs in Scotland, and is not uncommon in Sutherlandshire, but Kane does not include it in his Irish catalogue.
Clearings in woods are generally the best places in which to find this pretty little Fritillary; but it also seems to have a fondness for the margins of brooks and rills, where these run through or by the sides of woods. Usually it is on the wing in May or June, but sometimes, in early seasons, it puts in an appearance at the end of April. To entomologists of a bygone age it was known as the “April Fritillary,” but this name would hardly be a suitable one for it in the present day. Very rarely a few specimens have been taken in August; and there is at least one record of caterpillars that had ceased feeding in July, in the usual way, and were apparently settled down for hibernation, suddenly arousing from their slumbers, and completing their growth in August.
Abroad, the species is distributed throughout Europe, except the extreme south, and extends into Armenia, Northern Asia Minor, the Altai, and Amurland. It is stated to be double-brooded on the Continent.