By far the larger number of larvæ belong to this class; that is, they do not resemble the perfect insect. Do not resemble! could any one believe that these strange, and some of them awful looking larvæ ever became _butterflies_? yet they all belong to that tribe of insects.
In order to give a clear conception of the structure of a larva, we may briefly mention the names of its various parts. First then, there is a _head_ of various shapes, sometimes of the shape of a heart, sometimes round or triangular. Attached to the head are the two _antennæ_; or, as they are commonly called, _feelers_, most probably an incorrect expression, as it appears that insects may possibly _hear_ as well as feel by their means. At the side of the head are the _eyes_, which are formed much more simply than those of the perfect insect. Next is the _mouth_, provided with its upper and lower pair of jaws. Then there is the _body_ and its _legs_; and lastly, there is in many larvæ, living in the water, a _tail_, which, strange to say, is provided with a delicate tube, through which the larva breathes. A beautiful instance of such an appendage to the body of the larva, is represented in the adjoining cut; the various parts of the larva are also represented in the accompanying figure.
We may now enter upon a few particulars connected with the general history of insects in the larva form.
Generally, for a little while after the larva has emerged from the shell, it is in a very weak and languid condition. The effort of extricating itself from its little prison-house, seems to leave it almost without strength; and for a period which varies in different insects, it lies helpless and almost motionless at the mercy of any wandering adversary, and might be demolished without resistance. But this hour of weakness, except in a few cases, is not prolonged. In the course of an hour or two, or even much less in some instances, the larva revives, takes heart, and begins by eating whatever food may happen to lie in its way; and now the larva becomes a terror to the world of insects, or even, indirectly, to man and to nations. Instead of simply eating, in order to live, like most other beings, it only lives to eat; it has no other duty to perform at present but to eat as fast and as much as it possibly can in a certain time; and it must be confessed, the larva, generally speaking, leaves little to be desired on the score of a sharp appetite. Unlike other creatures who allow themselves a certain period between their meals, the larva sets to its feast and does not leave the table until it has devoured all its contents,--upon which it immediately begins again elsewhere. No _gourmand_ in the world, whether among human beings or brutes, can compare with the insect in this form for the amount of food consumed. Morning, noon, and night, is to it only a continued round of feasting; and, as may well be imagined, the larva grows very rapidly accordingly. Some larvæ consume animal, others vegetable food; or, in the language of science, some are _carnivorous_, some are _graminivorous_ or _herbivorous_, and some will eat anything almost that comes before them--these would be called, and very appropriately so, _omnivorous_.