James Duncan

“ Who has so great a genius, or is so conversant in the art of writing, as to be able to describe with a due sense, the trouble, the misfortunes this creature is subject to during the short continuance of its flying life? ”

“ When the vermicle, or young larva, has grown a little, four membranous buds or follicles, like flower-cups, are observed to spring out of the body near the end of the thorax; if opened at an early period, these are found to be mere bags, containing nothing but a watery ichor, but they soon become more matured, and the wings may be observed in them folded together. When full grown, all the varieties of colour and painting which distinguish the perfect insect, become transparent through the skin. The food of these larvae, he says, is soft mud, and the fine earthy substance in which they live. ”

“ The insects possessing the greatest powers of flight, must, therefore, be sought among those in which the upper wings are wholly membranous; and we accordingly find them among the Neuroptera, Hymenoptera, and Lepidoptera. Every one who has paid the slightest attention to the subject, must have noticed how much more vigorous and sustained is the flight of a dragon-fly, a bee, or a butterfly, than that of a beetle, a grasshopper, or a plant-bug. The under wings are in every instance membranous, and are exclusively organs of flight. ”

“ Viewing the animal kingdom as forming a progressive series, from the most simple to the most complex organism, insects may be regarded as occupying nearly the centre of the scale; for, though some properties might entitle them to rank higher, there are others in which they are so deficient, as completely to counterbalance that consideration. In muscular vigour, for example, and the complication of the digestive canal, they are almost equal to the vertebrata, while the circulating system is so imperfect, that it was, till lately, a matter of doubt whether it deserved the name. ”

“ Each of the luminous points is thus composed of a multitude of facets, and forms an apparatus entirely similar to that which Fresnel has invented for the diffusion of light, and which bears his name. When this corneous cap is removed, the luminous matter loses a great part of its brilliancy. Every thing, in other respects, is managed with a view to increase the light to the utmost. ”

“ If we are so liable to mistakes in regard to things that lie open to our inspection, what are we to say of our opinions of things that are invisible? How many idle notions are formed on such subjects! how many senseless conceits, with which, however, we sometimes suffer ourselves so far to be deluded that we make nothing of injuring, both in character and person, those who happen to be of a contrary opinion! It is therefore, absolutely necessary that we should always distrust ourselves and act with the greatest circumspection. ”

“ When the nervures of the upper wings exist in their maximum state of development, they are five in number. The longitudinal one placed along the anterior border of the wing, is usually called the costal nervure: it was named by Jurine, who first gave a nomenclature to these parts, the radius, from a notion that it was analogous to the bone so named in vertebrate animals. For the most part this is the strongest nervure in the wing, as it forms the anterior edge when that organ is extended, and has, therefore, to cut through the air during flight. ”

“ Many pupæ have strong angular points projecting from various parts of their bodies, and sometimes these are processes designed for a particular function. Such, for example, are the clavate appendages which project from the sides of the thorax in the pupæ of gnats, and some other dipterous species which live in the water. The dorsal segments of many are armed with sharp serratures looking towards the anus, which serve an important purpose in their economy, for it is by their means the pupa works its way to the surface of the ground, when the perfect insect is about to be disclosed. ”

“ Taste is one of the senses whose organs have not been fully determined. Judging from analogy, it should reside in that part of the mouth corresponding to the tongue, and as that exists in tolerable distinctness in many tribes, it has usually been assigned thereto. The membrane which lines the interior of the oral cavity, doubtlessly shares in this function; and in the suctorial races, which probably possess it in a very inferior degree, it must have its seat at the tip of the proboscis, which is commonly provided with glandular points. ”

“ The internal anatomy is also elaborately described and figured, constituting by far the most valuable portion of the work. The following remarks occur towards the close:—"All of these insects die in the very short space of time just mentioned, nor do any of them,—which is a matter very worthy of observation,—die a natural death on land; all of them invariably go to the water again, after they have gone through the second change of their skin. God, therefore, the Supreme Artist, has been pleased to assign this insect a short life that surpasses adoration. ”

“ The head is small, retractile, and variable in form even in the same individual,—that is to say, it is composed of a comparative soft fleshy substance which the insect can modify in shape at pleasure, to answer its various purposes. The colour is generally pale, but sometimes it is dark, and even bright red. The stigmata, in the species not aquatic, are most commonly placed in a cavity in the hinder segment of the body, which is capable of closing over them, so as to preserve them from being closed up by the fluid and putrid substances among which the larvæ often live. ”

“ Muscular System.—When we reflect on the varied movements of insects, their different modes of progression, walking, leaping, swimming, flying, &c. and the great degree of strength which they exhibit, it is evident that their apparatus of muscles, on which all these acts depend, must be at once ample and powerful. Although Lyonnet's enumeration of the muscles of the cossus has been often cited, we are acquainted with no other instance which so well exemplifies their wonderful multiplicity. ”

“ The nymph or pupa does not differ from the larva, except in bearing on the back a pair of rudimentary wings, enclosed in a kind of sheath. The larvæ and pupa are, of course, incapable of flight, but the mature insect springs into the air with great facility, and expanding its capacious wings, can sustain itself for a considerable time. In ordinary cases, they traverse but short spaces at a time; but when any change of place becomes requisite, they are able, like their relatives the locusts, to fly both high and far. ”

“ To the secretion of poison, and the beautifully constructed instrument by which it is injected into the body of an enemy, insects are indebted for one of the most effectual means of defence which has been assigned to any kind of animal. It is limited to the Hymenoptera, and among these we are most familiar with its effects in bees and wasps. The poison is contained in a round or ovate bladder, lying very near the hinder extremity of the abdomen, and is discharged into the sting by a narrow duct. ”

“ Thirdly, the nervous system may exercise a certain influence upon the production of the light; for as it is the chief agent of all the voluntary actions of the body, it will also necessarily exercise an influence upon the voluntary suppression of the light, if the insect stop this influence by checking respiration in the way in which it causes the nerve to act upon the muscle in muscular motion. ”

“ The hinder tibiæ sometimes present the peculiarity of being furnished with very broad foliaceous expansions, irregularly toothed on the edge; in some instances as wide as the body, and strongly contrasting with it by being of an entirely different colour. Such broad surfaces exposed to the air must exercise considerable influence on flight, and are probably of service in balancing the body. The number of joints in the tarsi varies from one to five, but when the latter amount occurs it is not in all the tarsi, there being no example of a strictly pentamerous species in this order. ”

“ It has been well observed that each of the three great divisions of the body is the appointed seat of a separate set of organs, all of them alike important in the animal economy. As the head contains the organs of mastication, and the thorax those of motion, so the abdomen is the appropriate site of the generative organs. These, however, are chiefly internal, and will be most conveniently considered when treating of the anatomy of the abdomen. ”

“ The consumption of food is necessarily great, in some cases exceeding that of any other animals, regard being had to their respective size. In fact, many of the kinds which consume the foliage of plants eat with little intermission; and, in some instances, they continue to feed both by night and day. The growth of the larvæ of flesh-flies (Sarcophaga) is unusually rapid, some of them having been found to become 200 times heavier in twenty-four hours. When it has attained its full growth, the caterpillar of the goat moth is sometimes 72,000 times heavier than when newly hatched. ”

“ They often fly into persons' faces or bosoms, and, their legs being armed with long spines, the pricking excites a sudden horror not easily described. In old houses they swarm by myriads, making every part filthy beyond description wherever they harbour, which, in the day time, is in dark corners, behind all sorts of clothes, in trunks, boxes, and, in short, every place where they can lie concealed. ”

“ Nearly all insects inhabiting the land and the air, as well as the amphibious species (Dytiscidæ, &c.) , receive their supply immediately from the atmosphere which surrounds them on all sides, and it is admitted by apertures named spiracles or stigmata. These are small perforations, commonly of an oval or rounded form, placed along the lateral margins of the body. In number, and almost every other respect, they vary greatly, but their arrangement is always symetrical, one on the right side, and another on the left; each segment, for the most part, being thus furnished with a pair. ”

“ Several anomalies have already been alluded to in the structure of earwigs, and it remains to be added that a very remarkable one also occurs in their economy. Frisch, De Geer, and many other entomologists have observed the female watching over her eggs with great care, and even covering them with her body as if on purpose to hatch them, a fact whicb is well known to those who are in the habit of overturning stones in search of insects. ”

“ In the higher animals, it is scarcely necessary to remind the reader, the chyle is absorbed from the alimentary canal by the lymphatic vessels, and conveyed to the venous blood, with which it repairs to the lungs or gills in order to be oxydised. No such conduits as absorbent vessels or veins existing in insects, the chyle merely transudes through the parietes of the digestive tube into the cavity of the body, whence it finds its way to a large cylindrical canal placed near the back, from which it receives an impulse which conveys it to different parts of the body. ”

“ Muscles of the Thorax.—The muscular system of the thorax has for its office to unite the component segments of that portion of the body, and to furnish a motive apparatus for the organs of locomotion, the wings and legs. They differ somewhat according as the prothorax is free or connate with the succeeding segments. In the former case, (as among the Coleoptera, for example,) the principal mass of the muscles is concentrated in the prothorax, and they are almost wholly employed in effecting its free movements, there being no wings to be supplied. ”

“ The forms and appearance of the common earwig are so familiar to all, that we have thought it unnecessary to figure any of the species, especially since they are all very similar to each other; but as they present several peculiarities in their structure and habits, it is necessary to give some account of them, otherwise our exposition of this order would be incomplete. It has been already mentioned, that the disposition of the wings does not correspond to what is observed in other Orthoptera, since they are folded both longitudinally and transversely. ”