Purple Thorn (Selenia tetralunaria).
On Plate [112], Fig. 5 represents a specimen of the spring brood, and Fig. 6 one of the summer brood (var. æstiva, Staudinger). The ground colour of the typical form is whitish, sometimes tinged with grey, and sometimes with pinkish; the patch at the tip, and the basal two-thirds of the fore wings, also the basal half of the hind wings, are purplish brown, varying almost to blackish; or they may be rich red brown. Var. æstiva is rarely whitish in ground colour, but this is frequently of a pinkish tinge, and the darker portions of the wings are brownish, inclining to olive; sometimes the general colour is ochreous brown with dark brown cross lines, and a rust-coloured lunule at the tips of the fore wings. The hybrid resulting from a female of this species that had paired with a male bilunaria has been named parvilunaria, Bastel. At the time it is laid, the egg is pale olive green, but it changes to shining reddish, and just before hatching to purplish black. (Plate [113], Fig. 1a.)
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| 2 Pl. 112. |
| 1-3. | Early Thorn. | 4. | Lunar Thorn. |
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| 5, 6. | Purple Thorn. | 7, 8. | Lilac Beauty. |
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| 2 Pl. 113. |
| 1, 1a. | Purple Thorn: eggs and caterpillar. |
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| 2, 2a. | Lunar Thorn: caterpillar and chrysalis. |
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| 3. | August Thorn: caterpillar. |
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The caterpillar is reddish brown, mottled with darker brown, and with pale greyish. It feeds on birch, alder, oak, sallow, cherry, etc.: June and July, and again in the autumn. (Plate [113], Fig. 1.)
The moth is out in April and May, and the second generation emerges in July and August. A few specimens of a third generation have been reared in October, but this is unusual.
The species is more or less local, and rarely common, at least in the moth state; it occurs in all the southern counties of England, and a few specimens have been recorded from some of the midland and northern counties, and from South Wales. In Scotland, only noted from Rannoch, Perthshire, and a specimen was reared on April 25, 1901, from a caterpillar found at Dunkeld, in the same county, the previous autumn.