3042 THE JOINTED ANIMALS 



beneath moss or bark, wherever the larva has crawled to effect the change, without 

 any additional covering. Others form a hard cocoon of the grains of mold, to 

 which consistency is given by means of a gummy secretion furnished by the larva. 

 Many form with this secretion a hard case, the outer side covered with chips of the 

 surrounding bark, which, owing to their similarity to the surroundings, serve as a 

 protection from observation. Others spin a silken egg-shaped cocoon, sometimes 

 fiocculent and broken, sometimes formed of yards and yards of silken thread, 

 emitted from the mouth and passed over and under, across and round, until the cell 

 is complete Among the more interesting of these cocoons is that of the emperor 

 moth, which forms a short tubular exit closed against the entrance of earwigs and 

 other insects by a circular series of fine bristles directed outward and converging to 

 a point. The principle of contrivance is the same as that employed in the manu- 

 facture of lobster pots; but here the process is reversed, for in this case it admits 

 of a ready egress but prevents any entrance. Moths whose pupa stage is passed 

 within an external cocoon have a double task before them when the time is ripe for 

 an emergence. The pupa itself as does also the chrysalis of butterflies splits at 

 the dorsal suture above the thorax, and the moth emerges, ferreting a way through 

 one end of the cocoon, which seems to be softened by moisture from within, and 

 thus escapes. The imago or perfect insect, having now emerged, climbs to some 

 point of vantage, where the wings, still very small, though completely formed, are 

 allowed to hang downward, expand and harden in the air. After a few hours they 

 are stiff and ready for use. 



At no stage in their lives are lepidopterous insects free from the 



attacks of enemies. In the egg state they fall a prey to beetles and 

 small birds, and as larvae they are extremely liable to receive a deadly thrust with 

 the ovipositor (or sting) of an ichneumon. As the ichneumon grubs grow at the 

 expense of their host, scarcely a tissue in the whole body may remain, save those 

 needful for the carrying out of life-supporting functions. And at last, when the 

 grubs are themselves ready to pupate, and have no further need of their host, they 

 finish up the rest and the larva dies chiefly because there is nothing left to live. 

 The enemies of the imago, whether butterflies or moths, are numerous. Birds, 

 bats, dragon flies, etc., pursue and harass them whenever they happen to meet 

 with them. The marvel is that any remain alive to lay eggs and perpetuate the 

 species. 



In the struggle to escape detection and capture, all unconscious though 



it may be, arises the phenomenon previously alluded to, and known 

 as protective mimicry. The kindred phenomenon of protective coloring, when the 

 moth or butterfly merely resembles in hue the bark, leaf, or twig on which it rests; 

 also protective resemblance, simply when insects take the form of objects, such as 

 twigs, dead leaves, bits of decayed wood, flakes of white bird droppings; these are 

 all well known. But protective mimicry means more, it implies the actual mimick- 

 ing either the form, color, or habits of some other insect which is either too savage 

 or unpleasant to make it a desirable object of food; as, for instance, the clearwing 

 moths mimic gnats, bees, wasps, ichneumons, etc. Perhaps the most curious 

 instance is that of the Kallimas or dead-leaf butterflies of Northern India, whose 



