ANATOMY OF LEPIDOPTERA. 23 



Many larvae are smooth and naked, or thinly covered with hair. Others are covered with a close 

 pile, and some, like the Tiger Moths (Arctiidce), with thick, shaggy hair. Some are tufted or spiny, 

 while others are furnished with humps, warts, or tubercles, varying in size and position according to 

 the species, and the tufts of hair are often placed upon such prominences. The retractile appendages 

 at the extremity of the body of the larva of Cerura vinula, already mentioned, as well as the retractile 

 fork found on the back of the neck of the larvae of all the true Papilionidce, are believed to be 

 designed to drive away Ichneumon Flies or other enemies. Birds will seldom eat brightly-coloured or 

 hairy larvae, but they greedily devour naked larvae of a green or brown colour, which rely rather on 

 means of concealment than on external defences against their enemies. But some larvae are furnished 

 with very formidable weapons. The nests of the different species of Processionary Caterpillars 

 (Cnethocampa) are dangerous to approach, on account of the fine barbed hairs of the caterpillars 

 and a highly irritating dust, which floats about in the surrounding air. Many foreign larvae, chiefly 

 belonging to the Sombyces, are actually provided with clusters of stings, consisting sometimes of fleshy 

 branching spines, some of which are thick and truncated at the extremity, and set with fine, sharp, 

 stinging bristles, while others are simply pointed. Others are provided with tufts of hair, some 

 bristle-like and others finely pointed ; while the broad footless larvae of the Limacodidce are 

 provided with spines filled with a coloured liquid, and terminating in a knob set with short sharp 

 bristles. These fascicles of stings are darted forth by the larva whenever it is alarmed, and cause a 

 long-continued burning pain. 



The basis of the nervous system in insects consists of two double longitudinal cords running 

 along the under surface of the body (see Vol. V., pp. 290, 291). Each of these is itself double, 

 and the upper one is very indistinctly marked in Lepidoptera. It is in the lower one only 

 that ganglia, or knots of nervous matter, are placed. In the larvae of Lepidoptera there are 

 thirteen pairs of ganglia. The anterior pair, situated above the oesophagus, or gullet, represents the 

 brain ; and the first of those situated below it represents the medulla oblongata. Leaving this, which 

 Newport calls the first sub-oesophageal ganglion, the cords which correspond to the crura run on each 

 side of the oesophagus into the second segment, where they form the second sub-oesophageal ganglion. 

 Beyond this and the following ganglion, which is placed at the back of the third segment, the cords 

 diverge to include the insertion of the first and second series of diagonal muscles ; the two following 

 ganglia, situated towards the extremity of the fourth and fifth segments respectively, completing the 

 thoracic system. The cords are continued beyond, forming a double ganglion in each segment up to 

 the eleventh, where the large terminal ganglion, formed by the fusion of those belonging to the 

 eleventh and twelfth segments, is situated. In some larvae these ganglia are distinctly separated, 

 in which case fourteen pairs are present instead of thirteen. Great changes, however, take place 

 in the nervous system during the pupa state, when the four thoracic ganglia fuse into two large 

 ones, which distribute nerves to the legs and the muscles of the wings, while the two following ganglia 

 either disappear entirely or amalgamate with the others. 



The digestive system is very simple in the larvae of Lepidoptera, in which it commences by a 

 distinct oesophagus, which terminates by a valvular orifice in the third segment in a long muscular 

 stomach, terminating in the pylorus and ilium. The Malpighian vessels empty themselves into the 

 ilium, which is followed by a lobed caecum, a very large colon, and a short rectum. Of the muscles of 

 larvae, suffice it to say that they are very numerous and complicated, especially in the head, in 

 which the large muscles which move the mandibles occupy the greater part of the back and sides. 



The respiratory and circulatory systems differ little from those of other insects, but a few 

 aquatic larvae (Paraponyx, &c.), are provided with branchiae. 



The food of caterpillars is very various, and there is scarcely any animal or vegetable substance 

 which some of them will not attack. But though many species will eat a variety of plants, others are 

 only able to subsist on one, or at most two or three ; and all are more or less restricted in their food, 

 and must die if they cannot obtain it. The great majority live exposed, and feed on the leaves of 

 plants, but some prefer the flowers or seeds. Others are internal feeders, and live actually within 

 the stems of plants, or even in the branches, trunks, or roots of trees, boring galleries through the 

 solid wood, and often destroying the trees. Some caterpillars prefer withered leaves to fresh, and 

 others, chiefly among the smaller Moths, feed on butter, leather, horn, dried fruits, corn, hair, cloth, 



