At the best of times it is not an active insect, and on a cold or a dull day hundreds of them may be seen clinging to the upright grass stems, from which they can be removed at pleasure.
The caterpillar of this beautiful moth keeps close to the ground, and feeds on grasses, the speedwell, dandelion, and other plants. When it is about to become a pupa, it ascends some slender upright plant, generally a grass stem, and then spins for itself the residence which is represented on the plate.
In this state it may be gathered, and placed under a glass shade; and in the summer months the perfect insect will make its appearance. There are some places which it specially favours, and where it may be found in great profusion. At Hastings, for example, the fields about the cliffs were so populated by these moths, that hardly a grass stem was without its Burnet-moth’s habitation.
Feeding on the same plant as the Tiger-moth caterpillar, may often be found another caterpillar of a very different aspect. It is very much larger, and instead of presenting an array of stiff bristles, is covered with thick soft hair of a yellowish-brown colour, diversified with stripes of a deep velvety black, arranged so as to resemble the slashed vestments that were so fashionable some centuries ago.
This caterpillar is the larva of the Oak Egger-moth, and is not so remarkable as a caterpillar as for the house which it builds for its pupal residence.
After changing its skin the requisite number of times, the caterpillar ceases to feed, and, proceeding to some convenient spot (generally a faded thorn-branch), spins its temporary habitation. This cocoon, as it is called, is about an inch in length; and into that narrow space the creature contrives to push, not only itself, but also its last and largest skin.
The substance of the cocoon is hard and rather brittle when dry; and in texture somewhat resembles thin brown cardboard. In its substance, and on its surface, are woven many of the hairs with which the caterpillar is furnished. If the cocoon is carefully opened, the chrysalis will be found within, its head towards the spot where the moth is to emerge, and the cast caterpillar-skin crumpled down by its tail.
In course of time, the chrysalis passes through its development, and the egger-moth itself pushes its way out of the cocoon, with wings and body wet and wrinkled, but soon to assume their proper form and strength. The cocoon is shown at [plate I], fig. 5 a.
Sometimes the cocoon remains unbroken beyond the proper season; and if it is examined, one or two little holes will generally be found in it. These are signs that the egger has met with an untimely fate, and that it has fallen a victim to those scourges of the insect world, the ichneumon flies. Of these creatures we shall speak in a future page, and therefore omit to describe them here. The moth is shown at fig. 5.