Fig. 22. Web of Lackey Caterpillars. (Photo by W. J. Lucas.)
The full-grown caterpillar is slaty blue above; along the middle of the back is a bluish white line, bordered on each side by a reddish-orange-lined black stripe; towards the lower limit of the slaty blue colour is a black edged reddish-orange line, and below this again the ground colour is flecked with orange, sometimes forming a line in the region of the spiracles; there are two velvety black spots on the back of the ring nearest the head, and a smaller black spot on each side of the next two rings; the hairs are brownish, rather more numerous on the sides than on the back. Head slaty-blue with two black eye-like spots. It feeds from April to June on hawthorn, sloe, and various fruit trees in orchards and gardens; also on birch, elm, oak, sallow, willow, etc.
Chrysalis blackish, rather downy enclosed in a double
oval-shaped cocoon; the inner compartment is of rather closer woven silk, and is thickly covered with a yellowish substance, which is ejected by the caterpillar as a fluid, and afterwards drying forms a sulphur-like powder on the cocoon, and in a lesser degree on the chrysalis also. The moth is on the wing in July and August, but it is rarely seen in the daytime, and not often at night, except when attracted by light into the house, or to the gas or electric lamps. It is exceedingly easy to rear, either from eggs or from collected caterpillars; the latter are often abundant.
Generally distributed throughout England, but becoming scarcer from the Midlands to Lancashire and Yorkshire, and not often occurring further north than the last named county. In Ireland it is unknown in the north, but occurs in many parts of the south and south-west.
The Ground Lackey (Malacosoma castrensis).
This also is a variable species. Most frequently the fore wings of the male are pale buff, cross lined, and more or less clouded with brown; hind wings brown. The female has all the wings reddish brown, the front pair being crossed by two pale buff lines. The fringes are pale buff, chequered with brown in both sexes. Colour and marking are, however, subject to considerable variation. Sometimes all the wings are pale buff (male), or reddish brown (both sexes), and the fore wings without marking. The cross lines on fore wings of the female may be either very slender or very broad; occasionally almost the whole of the basal area up to, and including, the first cross line is buff. Two examples of each sex are shown on Plate [48].
The eggs are laid in a similar manner to those of the last species, around stems of wild carrot, sea wormwood, and other
plants that flourish in the insects' favourite haunts, which, in this country, are the salt marshes along the estuaries of the Thames and Medway.
The caterpillar is black, inclining to bluish between the rings; along the back are four much broken reddish orange lines and a central bluish line; a bluish stripe followed by a reddish one along the sides, and below this the colour is bluish, speckled with black; the hairs are golden brown. Head blackish grey, without black spots (Plate [49], Fig. 3).