The male has the wings rather more ample than the same sex of the last species, the colour is a more ochreous red and there is a large white spot at the lower angle of the fore wings, but no white mark at the tips of these wings. Specimens from the north of England are rather darker than southern examples. In the course of temperature experiments it has been noted that the colour of the moth is darkened if the chrysalids are put in a refrigerator for a few weeks, and then brought into a mean temperature of 40° Fahr. In the female the appendages representing wings are somewhat larger than those of the female of the Scarce Vapourer, but are quite useless as organs of flight (Plate [40], Figs. 4, 6).
In general colour the caterpillar is violet or smoky grey; the markings on the back comprise a creamy, red-dotted line along the middle area, this is edged with black, and on each side of it is a series of raised red spots; the broken line along the sides is yellowish, and the four brushes of hair on the back are yellow, sometimes merging into brown above; the pencils of longer hairs are blackish on the ring nearest the head, and dark grey or brownish on the last ring. It may be found through the summer on the leaves of most trees and bushes. Chrysalis blackish, glossy, and rather hairy. The cocoons are spun up in the crevices of bark on tree trunks, or in the fork of a twig, under the eaves of an out-house or shed, on palings and fences, etc. The hairs of the caterpillar are mixed with the silk of the cocoon; the female lays her pale brownish eggs, which are minutely pitted and have a darker ring below the sunken top, on the outside of the cocoon, and there they remain through the winter.
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| Pl. 40. |
| 1. Dark Tussock Moth, male; 2 female. | 3. Scarce Vapourer, male; 5 female. |
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| 4. Vapourer, male; 6 female. | 7. Pale Tussock, male; 8 female. |
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| Pl. 41. |
| 1, 1a. | Scarce Vapourer: caterpillar and cocoon. |
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| 2, 2a. | Common Vapourer: egg-batch on cocoon and enlarged egg. |
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| 3, 3a, 3b, 3c. | Pale Tussock: egg, caterpillar, chrysalis and cocoon. |
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| 4. | Dark Tussock: caterpillar. |
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Generally distributed throughout the United Kingdom, but not so common in Ireland as in England and Scotland. It is quite a Cockney insect, and is found in almost every part of the Metropolis where there are a few trees. Occurs practically over the whole of Europe, and in North-east Asia Minor, Armenia, Siberia, Amurland, and North America.
The Dark Tussock (Dasychira fascelina).
The figures of the sexes of this species on Plate [40] represent the dark grey form. Sometimes the forewings are whitish grey and occasionally slaty grey; the cross lines may be stronger or fainter, and in some specimens are nearly absent; the yellowish colour usually seen on the cross lines may be missing, or, on the other hand, other parts of the wings may be stippled with yellowish. Laying her eggs in batches, the female carefully covers them with dark brown hairs from the tuft at the end of her body.