540 



AKTIOULATA. 



Althoiiifh we have already noticed the wonderful transformations which insects undergo, we 

 must still g'^'' '<■ """"0 detailed account of them. As has been stated, in their regular develop- 

 ment from the eirg tlu-v in general i>ass through a certain series of changes, which together con- 

 stitute what is called (he melomorp/ioxis, the young animal on emerging from the egg generally 

 exliihiting an a])|)earance very different from what it is ultimately destined to assume. The de- 

 gree of this metamorphosis is, however, very different in different groups of insects. In its most 

 coujplete form, as e.\emplilic<l in the butterflies, moths, beetles, and many other insects, the meta- 

 morphosis takes place in three very distinct stages. In the first, which is called the larva state, 

 the insect has the form of a grub, sometimes furnished with feet, sometimes destitute of those 

 organs. Ditlereiit forms of insects in this state are popularly known as caterpillars, (jrubs, and 

 maqriots. During this period of its existence the whole business of the insect is eating, which it 

 usually performs most voraciously, changing its skin repeatedly to allow for the rapid increase in 

 its bulk; and after remainiTig in this form for a certain time, which varies greatly in different spe- 

 cies, it passes \o the second period of its existence, in which it is denominated a pu2)a or chri/saUs. 

 In this condition the insect is quiescent, neither eating nor moving. It is sometimes com- 

 pletelv inclosed in a horny case, in which the position of the limbs of the future insect is indi- 

 cated by ridges and prominences; sometimes it is covered with a case of a softer consistence, which 

 fits closely round the limbs, as well as the body, thus leaving the former a certain amount of 

 freedom. I'upie of this description are sometimes inclosed within the dried larva skin, which 

 then forms a horny case for the protection of its tender and helpless inmate. After lying in this 

 manner, with scarcely a sign of life, for a longer or shorter period, the insect, arrived at maturity, 

 bursts from its prison in the full enjoyment of all its faculties. It is then said to be in the Inicf/o 

 or perfect state. 



This metamorphosis is one of the most remarkable phenomena in the history of insects, and 

 was lono- regarded as perhaps the most marvelous thing in nature, although recent researches 

 have shown that the history of many of the lower animals presents us with circumstances equally 

 if not still more wonderful. Nevertheless, the metamorphosis of the higher insects is a phenom- 

 enon which cannot fail to arrest our attention. To see the same animal appearing first as a soft 

 worm-like creature, crawling slowly along, and devouring every thing that comes in its way, and 

 then, after an intermediate period of death-like repose, emerging from its quiescent state, fur- 

 nished Avith wings, adorned with brilliant colors, and confined in its choice of food to the most 

 delicate fluids of the vegetable kingdom, is a spectacle that must be regarded with the highest 

 interest, especially Avhen we remember that these dissimilar creatures are all composed of the 

 same elements, and that the principal organs of the adult animal were in a manner shadowed 

 forth in all its previous stages. 



But although the majority of the class of Insects undergo a complete metamorphosis of this 

 description, there are many in which the only transformation consists in a series of changes of 

 skin, without any interval of rest, the larva, which from the first presents a certain degree of re- 

 semblance to its parents, gradually acquiring those organs which it originally wanted. In this 

 metamorphosis, whicii is called incomph'tc, the principal difference between the larva and the 

 imago consists in the absence of wings, which first make their appearance in the form of thick 

 lobes, inclosed in cases, in the course of the last changes of the skin. The joints of the antennae 

 and tarsi are also sometimes fewer in number ; and the ocelli, or simple eyes, are generally want- 

 ing in the larva when present in the perfect insect. In some insects, such as the dragon-flies, 

 the May-flies, and some others, the larva?, which are aquatic, present a greater difference from 



hatched by the returning warmth of spring, giving birth to a wingless, hexapod larva. This larva, if circumstances 

 — such as warmth and food — be favorable, will produce a hrood, or, indeed, a succession of broods, of eight ktrva like 

 itself without an// connection with the male. In fact no winged females have at ihis season appeared. If the virgin 

 progeny be also kept from any access to the male, each will again produce a brood of the same number of aphides, 

 and careful experiments prove that this procreation from a virgin mother will continue to the seventh, the ninth, or 

 the eleventh generation, before the spermatic virtue of the ancestral coitus be exhausted. In the last larval brood, in- 

 dividual growth and development proceed farther than in the parent, and some individuals become metamorphosed | 

 into winged males — others into oviparous females. By these the ova are developed, impregnated, and oviposited, and 

 thus provision is made for disseminating the individuals, and for continuing the existence of the species over the 

 severe famine months of winter. 



