The Gipsy (Lymantria dispar).
Up to some sixty-five years ago, this species (Plate [46], Figs. 1 ♂, 2 ♀) seems to have flourished in a wild state in the fens of Norfolk and Cambridgeshire, and also in Huntingdonshire. Just how long it had been common in those localities history does not inform us, but about 1792 Donovan was unable to obtain a native specimen to figure. Stephens, however, writing in 1828 states that at that time it abounded in the Huntingdonshire fens. "It is said," he remarks "to have been introduced into Britain by eggs imported by Mr. Collinson, but the abundance with which it occurs near
Whittlesea, and the dissimilarity of the indigenous specimens (which are invariably paler, with stronger markings) to the foreigner, sufficiently refute that opinion." There appears to be no doubt that some time near 1840 the Gipsy moth began to decrease in numbers, and that about 1850 it had almost or quite ceased to exist, as a wildling, in England. At the present time, and probably since the date last mentioned, the species has been semi-domesticated, and so reared year by year, at first possibly direct from the original wild stock, but afterwards from fresh stock derived from eggs of foreign origin. Futile attempts have been made to re-establish the species in various parts of England, and also in Ireland. Such failure is curious, seeing that in America the accidental introduction of a few moths has resulted in the species becoming so numerous that at least one state has been expending thousands of dollars in endeavouring to destroy it. The eggs are laid in batches and covered with the down-like scales from the anal tuft of the female.
The caterpillar hatches in April, and in warm weather feeds up pretty quickly. It is grey, covered with black dots and fine marks; the hairs arising in spreading tufts from the raised warts, are longer on the sides than on the back; these warts on the back on each side of the pale central line are bluish on rings one to five, and reddish thence to eleven. Head, pale brown marked with black. Feeds on the foliage of most fruit trees, also on oak, elm, sallow, hawthorn, and sloe.
Chrysalis rather hairy, brownish in colour, in a fairly strong silken cocoon, which is spun up in any suitable angle.
The moths appear in August, and there is a striking difference in the size and coloration of the sexes. The male is pale or greyish brown, lined and clouded with darker brown on the fore wings, and the female is whitish with brownish cross lines, and a black central V-mark on the fore wings.
Distributed over the whole of the Palæarctic Region, except
the most northern, and, as adverted to, it has now become a pest in parts of North America.
The Black Arches (Lymantria monacha).
Two examples of each sex of this moth are figured on Plate [46], and these show the normal form of the species; the central markings of the fore wings vary in width and intensity, and in some specimens the whole of the central area is more or less filled up with black or sooty black. Sometimes the wings are partially suffused with blackish, and the normal markings are consequently somewhat obscured. Examples wholly suffused with black are referable to var. eremita, a form not uncommon on the continent, and modifications of it are found in a wild state in this country. By selecting parents showing a tendency to vary in the direction of this dark form, it has been found possible to obtain a good percentage of darkened specimens, some of them closely approximating to var. eremita.