Insect Importance.

The Living age 103, 2.5.1846

From Chambers' Journal.

Insignificant as insects may appear to the casual observer, there are families of the race which assume the highest importance, either from the benefits they confer or from the ravages they commit. We grant that it is neither a very dignified nor always a very accurate mode of estimating the importance of the lower animals to judge of them merely as they may subserve or thwart the purposes of man; but taking even this standard, we shall find that insects are not the insignificant creatures we vulgarly esteem them. Individually, the highest of the clam, is but a feeble instrument either for good or for evil: it is the infinity of their nunibers, and the fact of their generally living and acting in community, that renders than special objects of human consideration. We shall glance, in the present paper, at a few whose produce gives to them an economical and commercial importance.

By far the most valuable of the class is the silkworm, (Bombyx mori,) whose splendid tissue has been known from the remotest antiquity. Though early cultivated in China and India, it was not till the beginning of the sixth century that the insect was brought into Europe. Since then the culture and manufacture of silk has extended ever Italy, France, and other southern countries, holding a high place in their economy, giving employment to a vast number of hands, setting in circulation a large amount of capital, and involving much intricate and difficult fiscal regulation.

It is not our intention to enter upon the natural history of the silkworm—which, like many other insects, passes through the successive stages of egg, caterpillar, chrysalis, and moth—farther than to remark that it is in its second stage that it becomes economically important. Each moth having dropped to the number of 300 or 500 eggs, these are hatched by natural or artificial heat, according to the climate of the country, and a voracious caterpillar is the produce, which is carefully tended and fed with mulberry leaves, or with lettuce—both of these plants abounding in a tenacious juice or caoutchouc. On acquiring its full growth, (about three inches in length,) this caterpillar spins for itself an ovalshaped cocoon, funned by a single filament of yellow silk, from ten to twelve yards in length, emitted from the stomach of the insect preparatory to its assuming the chrysalis form. It is in this state that the silk is taken, the insect being destroyed by immersion in warm water, and the cocoon carefully unwound. Were the cocoon left undisturbed till the chrysalis had become a moth, the latter would eat its way through the envelope, and so cut the silk into a number of short lengths, instead of one continuous filament. Of course a sufficient number of cocoons are left untouched for next year's brood, comparatively few moths being sufficient to stock an extensive establishment. It is thus that a plain-looking, greedy, leaf-devouring insect becomes of so much economical importance; requiring human attention to supply it with food and shelter, hands to unwind the silken cerement, to assort and twist the filaments into threads, cords, &c.; individuals to dye, weave, and finish it — independent of the co-relative aids of chemists, designers of patterns, and framer% of the necessary machinery. Nor can this insect, humble as it may seem, be dispensed with so long as man admires and values the beauty of a silken fabric; for though he knows that the cocoon is obtained by the animal from the peculiar vegetables it feeds upon, yet all his boasted knowledge in chemistry has nut enabled him to elaborate from mulberry leaves a filament possessing the same lustre, beauty, and tenacity.

It is almost impossible to enumerate the various fabrics woven from silk, either for the purposes of dress, upholstery, or ornament; but an idea of its importance may be formed from the fact, that scarcely an individual, even in humble life, but can boast of wearing it to some extent, either for dress or ornament. In Britain the annual value of the manufacture is estimated at nearly ten millions sterling — more than nine tenths of which are for home consumption. We draw our chief supplies of the raw material from Bengal; from Italy, which produces about eleven million pounds annually; from China, where, next to tea, it is the staple article of export; from Turkey; and in smaller quantitics from Holland, the United States, and other countries. The foreign states in which the manufacture chiefly exists are China, India, Italy, Switzerland, and France; the latter kingdom alone producing fabrics to the annual value of about eight millions sterling. We have no very accurate data as to the amount of silk stuffs consumed in the various countries of the world; but considering how generally they are worn in oriental as well as in European countries, and reflecting upon the increasing demand by a civilized population in the Americas, we cannot be far wrong in stating that a million and a half of human beings derive their sole support from the culture and manufacture of silk, and that it creates an annual circulating medium of between thirty and forty millions sterling! So much for the importance of an humble insect which, if it had been shown to our ancestors five hundred years ago, would have been as little valued as the earth-worm beneath their sandals.

As an appropriate sequel to the silkworm, we may next advert to the cochineal insect, (Coccus cacti,) from which the red dye-stuff of that name is obtained. The male insect is winged, and not much larger than a flea; the female is wingless, and when full grown, about the size of a barley grain. It is the dried body of the female which forms the cochineal of commerce, having in this state the appearance of a shrivelled berry. It is principally used in dyeing scarlet, crimson, and other esteemed hues of which red forms the basis. The insect is found in Mexico, some of the southern states of the Union, and in the West Indies, and has we believe been introduced with some success into our East India possessions. The principal supply, however, is still from Mexico and the central states, where it forms a staple commodity of export. In a wild state, the cochineal insect feeds on various plants of the cactus tribe; but under cultivation it is confined to two or three species, which are found both to increases its size and color. The wild variety is gathered six times a year; but that which is cultivated is only collected thrice during the same period. Arrived at maturity, the insects become torpid, and are detached by a thin split of bamboo, or by a blunt knife—care being taken not to break them in the operation. They are then put into bags, and dipped in boiling water to kill them, after which they are dried in the sun; and though they lose about two thirds of their weight by this process, more than a million and a half pounds are brought annually to Europe. Some idea may be formed of the vast number of these creatures from the fact that each pound is supposed to contain about 70,000 insects. At present the value of cochineal fluctuates from six shillings to nine shillings per pound, which is scarcely a fourth part of the price obtained during the war, when it sometimes sold so high as thirtysix shillings and thirty-nine shillings a pound. At the present rate, Britain cannot pay less than £200,000 annually — for what! — the dried carcases of a tiny insect!

Lac, or gum-lac, with its various seed-lac, lumplac, shell-lac, &c., is also the produce of a small insect the Coccus ficus of Linnaeus, or the Kermes lacca of modern entomologists. This insect abounds in Bengal, Assam, Pegu, Siam, &c., and deposits its eggs on the leaves and branches of certain trees. So soon as deposited, the egg is covered by the insect with a quantity of this peculiar gum or lac, evidently intended to serve for a protection to the egg, and as food for the young maggot when produced. As each insect produces many eggs, and each egg has a separate envelope, the entire nest has a cellular arrangement as ingenious and compact as that of the bee. As there are myriads of these insects in every forest, the supply of lac may be said to be indefinite. In its natural state, this production is called stick-lac; after the cells are separated from the sticks and granulated, they are called seed-lac; this melted by fire and made into cakes, becomes lump-lac; and the term shell-lac is given to this substance after it has been again liquefied, strained, and formed into thin transparent plates. Lac also yields a fine red dye, which, though not so bright as cochineal, is said to be more permanent, and is often used as a substitute. From our East India possessions we annually export about 3,000,000 lbs. of shell-lac, and 1,000,000 of lac dye; about one half of which is, however, re-exported to Italy, Belgium, Germany, and other parts of the continent. We believe the present price of lac dye in the London market is from 2s. to 3s. per lb.. though it has been known to be so high as 8s. 6d.; stick-lac sells from £2 to £4 per hundred weight, and shell-lac from £3 to £5; so that a vast sum of money must be yearly expended on the produce of this — another bumble insect. The various lacs are employed in the manufacture of sealing-wax, ink, varnishes, and in hat-making.

We may here also notice the Coccus ilicis, or kermes — an insect from which Europeans obtained their most valuable scarlet dyes previous to the discovery of America. The kermes adhere to the shoots of the berry-bearing ilex, which is found very plentifully in many parts of Europe. They appear under the form of smooth shining grains of a brownish-red color, about the size of peas, and covered with a fine brown powder. These grains contain the young kermes, which proceed much in the same manner as the lac insect, till they attach themselves to the young branches, and become the receptacles of a future progeny. The scarlet dye obtained from the kermes is less brilliant, but more durable than that from the cochineal; old tapestries which were dyed with it two hundred years ago having lost scarcely anything of their original vividity. It is now little used, unless in Spain and other countries where the arts have yet made inconsiderable progress.

Known from the earliest periods of human history, and of more obvious importance than some of these dye insects, are the various kinds of honey bee — "the little busy bee" of the poet and moralist — the permanent symbol of industry and unprocrastinatiun. Plainlooking and humble as the common bee may appear, it divides with the silkworm the care and attention of man, and has had more books dedicated to its history and nurture than any other of the lower animals — the horse and ox perhaps excepted. At this moment we can lay our hands upon more than a score of treatises; nor does time seem to exhaust the subject, for every year is adding to our library of "bee books." And after all, this attention is not more than the brown dusty-looking little insect deserves. Its honey is one of the must delicious products in nature, and along with its wax subserves numerous purposes; whilst its roaming habits assist in carrying the fructifying pollen from plant to plant, thus not only rendering fertile that which would otherwise be hopelessly barren, but creating new and approved varieties. The silkworm acid cochineal insect require to be fed and cared for; the bee is a reveller in nature's common, trenches upon the store of no other creature, and converts into honey and wax what would otherwise be utterly useless. There cannot be a readier and more certain contributor to the income of the cottager than a snug little apiary, and even were it only in this light that the bee were useful, it would be deserving of all the importance with which it is invested. In Britain alone about £120,000 is annually spent fur foreign honey; and if we add to this a largo home supply, and consider that in other countries the article is even mote liberally made use of, we shall arrive at some conception of the economical value of the bee. But it is not the honey alone; we import 10,000 hundred weight of wax each year, and when we state that the price varies from £5 to £10 10s. a hundred weight, it will be seen that its value is all but equivalent to that of honey. In Holland, the southern states of Russia, in Greece, and other countnes of the Levant, as well as in America, the produce of bees forms an important item of their resources - resources, be it borne in mind, which could not be obtained by any other known means either in nature or art.

Our list would be incomplete without adverting to the insect which produces the gall-nuts of commerce, so extensively used in dyeing, in the manufacture of ink, and in other processes. These excrescences, varying from a quarter of an inch to an inch in diameter, are produced on several species of oak trees by the perforation of the female snips for the deposition of her eggs. The juices of the leaf being diverted from their proper channels by this puncture, they form a sort of wen, which increases in size, together with the larva inclosed in it. On the larva arriving at maturity, it eats its way out; hence gall-nuts are generally found with a hole in them. They are in perfection when they have acquired their full size and weight, but before the insect has pierced them; after which they become of a brighter color and lose part of their weight. Galls are produced abundantly throughout Asia Minor from a mall species of oak, but the best are those of Aleppo and Mosul, which are about the size of a nutmeg, and mostly of a bluish or gray color, hard, heavy, and compact, with numerous small tubercles on their surface. They abound in astringent matter, or tannin, and are much used in medicine as well as in the processes already alluded to. They are imported in great quantities, and vary from £2 to £4 a hundred weight, according to quality.

To these insects of utility we might add the Cantharis, or Spanish fly, used by the apothecary in the preparation of blister ointment; as well as many others of minor value; but our limits forbid. Enough, we should think, has been adduced to prove, even to the most heedless, that insects — laying aside altogether the purposes they fulfil in the scheme of nature - are economically not the insignificant and unimportant creatures which the uninformed mind is but too apt to regard them.