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| Pl. 111. | ||
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The Stout Dart (Agrotis ravida (obscura)).
The somewhat dingy brown, or greyish brown moth (Plate [107], Figs. 5 ♂, 6 ♀) is sometimes tinged with reddish, and this tint is generally present on the front or costal area.
The caterpillar is ochreous brown with a paler line along the back, and a series of dark edged, oblique and more or less curved, yellowish marks on each side; head greyish freckled with brownish; plate on first ring brown marked with pale lines. It feeds on low-growing plants such as dock, dandelion, chickweed, etc.; September to May. The moth flies in July and August, but its occurrence in Britain is somewhat irregular. It is found, sometimes commonly, in most of the southern and eastern counties of England, and also in Durham; and has been occasionally recorded from other parts of the country, as well as from Scotland. For several years it may seem to quite disappear and then suddenly become common in various districts. Its range abroad extends to Amurland, North China, Corea, and Japan.
The Northern Dart (Agrotis (Episilia) hyperborea).
Of this pretty Scottish species (alpina, Westw. and Humph.) four examples are figured in Plate [108]. Figs. 1 and 2 represent specimens from Shetland, and Figs. 4 and 5 are from Rannoch specimens. These will show something of the variation in this
moth, which was not known to occur in the British Isles until 1839, when a single specimen was taken on Cairn Gowr in Perthshire. No other example seems to have been noted up to 1854, when one was found on a rock in the same part of Perthshire. Up to the year 1876, only a few specimens had been obtained, but in that year, which was a hot and dry one in the Highlands, quite a number were secured. A female was also detected laying her yellowish white eggs on crowberry (Empetrum nigrum) and thus gave a clue which led to the subsequent discovery of caterpillars and chrysalids; and these have been obtained in some quantity. The caterpillar is reddish, inclining to pinkish brown, freckled with darker; three whitish lines on the back, the central one irregularly black dotted, edged on both sides with black, and the others with black bars along their inside edge; head pale brown freckled and lined with darker brown. It feeds from August to June (of the second year following hatching from the egg, it is said), on crowberry, bilberry (Vaccinium), and bearberry (Arctostaphylos uva-ursi).
The moth is out from late June until about the middle of August. It only occurs with us on the higher mountains in Perthshire, notably those to the south of Loch Rannoch; and at lower elevations in Unst, the most northern isle of the Shetland group. It has also been recorded from the Orkneys. Kane mentions a specimen bred at the end of February, 1893, at Clonbrock, Co. Galway, from a caterpillar found at a bog in the vicinity, where crowberry grows abundantly. Abroad the species in its typical form is found on mountains in Central and Southern Scandinavia, and in modified form in Silesia, Hungary, and Switzerland.