Volume I Part 13 (1/2)
Pl. 49.
1, 1a, 1b, 1c. LACKEY: _eggs, caterpillar, chrysalis and coc.o.o.n_.
2, 2a. HYBRID BETWEEN LACKEY AND GROUND LACKEY: _eggs and caterpillar_.
3. GROUND LACKEY: _caterpillar_.
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_Malacosoma_ hybr. _schaufussi_, Standf.--In 1884 Dr. Standfuss made some experiments in crossing three species of _Malacosoma_, and one of these was the pairing of _M. neustria_ [male] with _M. castrensis_ [female]; the offspring he christened as above. Since that time others have succeeded in crossing the two species with varying results.
On August 13, 1906, Mr. Percy Richards sent me a small batch of eggs (Plate 49, Fig. 2a) laid by a female, _M. castrensis_, that emerged in a breeding cage, and had paired with a captured male, _M. neustria_, he introduced.
The larvae hatched out one or two at a time, from April 7 over a period of more than a fortnight. Few of the caterpillars would commence to feed, and of those that took to the plum and sallow with which they were supplied, only four reached maturity. Three of these pupated during late June and early July, and three moths, all females, have emerged up to date, one on July 28, another on August 6, and a third on August 13. The second specimen was very much crippled, probably owing to the coc.o.o.n having been accidentally injured. One caterpillar was still feeding on August 14, but died about the 26th.
The mature larva (Plate 49, Fig. 2) has the head and markings thereon like _neustria_, also the black spots on the first thoracic segment, but they are rather large and inclined to unite. The bluish line along the sides is dotted and freckled with black rather more thickly than in _castrensis_; the dorsal line is very thin, but bluish as in _castrensis_, and the red lines on each side of it are broad.
In colour the three moths are deeper brown than any form of either parent species that I have seen, but the transverse lines, and especially the outer, are most like those of _neustria_.
It should be mentioned that much information on Hybridism in the Lackey moths and other species will be found in Tutt's ”British Lepidoptera,” vol.
ii. {112}
THE PALE OAK EGGAR (_Trichiura crataegi_).
In its typical form the male of this species (Plate 50, Figs. 1, 2) is ashy grey, with a darker central band on the fore wings; and the female is dusky greyish-brown, also with a darker band. The colour of the male varies in shade from almost whitish (var. _pallida_, Tutt), to blackish grey; in the paler forms the central band of the fore wings is often of a purplish tint, and in the darkest forms the band is almost black. The female var.
_pallida_, is pale buff.
The eggs, which are brownish, inclining to reddish on the micropylar area, are covered with dark grey hairs from the body of the female and laid side by side in a chain-like arrangement on a twig of hawthorn or sloe (those figured on Plate 51 were deposited in a box, and not securely attached).
From eight to twelve is said to be the usual number in a batch, and each female will deposit an average of 160 eggs.
The caterpillars do not hatch out all at the same time, but by ones and twos, at intervals spreading over a period of two, or perhaps three, weeks.
Several forms of the caterpillar have been described, but the ground colour is generally more or less black above and greyish on the sides; the ornamentation comprises interrupted white or whitish stripes, streaked or clouded with reddish, and reddish warts; the hairs are reddish brown. The example figured on Plate 51 was from eggs laid by a female moth in Selkirk, South Scotland. From the age of three weeks until it became full grown it was black marked with yellow on the back and orange on the sides; hairs pale greyish mixed with black ones, especially on the back towards the black, glossy, and somewhat hairy head. It hatched on April 26, was reared on plum, pupated early in June, and the moth, a darkish grey female, emerged on July 31. Another caterpillar that hatched on May 1, and two others from still later hatchings, were then in chrysalis.
[Ill.u.s.tration]
Pl. 50.
1. PALE OAK EGGAR, _male_; 2 _female_.
3. DECEMBER MOTH, _female_; 4 _male_.
5. SMALL EGGAR, _male_; 6 _female_.
[Ill.u.s.tration]
Pl. 51.
PALE OAK EGGAR.
_Eggs enlarged, and caterpillar._
{113} The caterpillar may be found from April to June on hawthorn and sloe, and it is said also on birch, oak, sallow, apple, bramble, etc. Those that I have found resting by day on shoots of hawthorn, apparently enjoying the suns.h.i.+ne, have almost invariably been ”ichneumoned”; but others that came up after sunset to feed on the shoots were generally healthy. Usually the caterpillar feeds up and pupates the same year, but on the moors in Aberdeens.h.i.+re and some other parts of Scotland it is said to hibernate and to complete its life cycle the following summer and autumn. Furthermore, the moths from these winter larvae are much darker than normal, and have been doubtfully referred to var. _ariae_, Hubn., a form found in the Alps, Scandinavia, and Finland.
The moth is out in August and September, and occurs in wooded districts throughout the southern half of England, but northwards from the Midlands it is uncommon; it is found in several parts of Scotland to Inverness. In Ireland it is reported (Birchall) to have occurred in Killarney, and Kane mentions that ”a blackish form was taken at Magilligan, near Derry, by W.
Salvage. Its larvae were feeding on blackthorn.” The range abroad extends through Europe to Armenia and Asia Minor.
THE DECEMBER MOTH (_Poecilocampa populi_).