on in the direction of the wind, and when any trench or rivulet occurs in their course, stop not for it, but fill it up with their own bodies, the general mass passing over their drowned or smothered companions without compunction. This plague had been, at the time of Mr Barrow's visit, in constant operation in Africa for three years. Russia and Poland were visited by locusts in 1650, on which occasion the air was darkened by them, and the ground covered to the depth of four feet: the trees were bent with their weight, and the amount of damage produced by them exceeded computation. In the sixth century, Italy was ravaged in a similar manner, and not relieved till a wind blew the invading myriads into the sea, when the smell of their bodies on the coast produced a plague, which carried off 1,000,000 of men and beasts. The prophet Joel expressively describes the locust as a devouring flame, before which the land is an Eden, and behind a desolate wilderness.

When we consider the vast amount of mischief produced by various insects, it seems surprising that they should have been gifted with such extraordinary powers of multiplication. When we inquire, however, into this, as into all other evils, we find that it is only an exception from a general good-the chief end of voracious insects being to remove animal and vegetable matters, which would otherwise be noxious. In the design of the world, only general results have been contemplated, and only general powers given. It is enough for nature if the grand end be accomplished.

We shall conclude with an extract from Latrobe's Travels in North America, respecting an insect of the grasshopper kind, named the Cicada Septendecim :

'The observation of a past century had shewn the inhabitants of Maryland and Pennsylvania, that every seventeenth year they were visited by a countless horde of insects of the cicada tribe, hence called Septendecim; distinct in aspect and habits from those whose annual appearance and mode of life were understood. Its last appearance had been in 1817, and its reappearance was

thus confidently predicted for the third or fourth week in May this year (1834). Nature, true to her impulses, and the laws by which she is so mysteriously governed, did not fail to fulfil the prediction. On the 24th May and following day, the whole surface of the country in and about the city of Philadelphia suddenly teemed with this singular insect. The subject interested me, and as during those days I had every opportunity of being daily, nay, hourly, attentive to the phenomena connected with it, both here and in Maryland, I send you the result of my observations. The first day of their appearance, their numbers were comparatively few; the second, they came by myriads; and yet a day or two might pass before they reached their full number. I happened to be abroad on the bright sunny morning which might be called the day of their birth. At early morning the insect, in the pupa state, may be observed issuing from the earth in every direction, by the help of a set of strongly barbed claws on the fore-legs. Its colour, then, is of a uniform dull brown, and it strongly resembles the perfect insect in form, excepting the absence of wings, ornaments, and antennæ. The first impulse of the imperfect insect on detaching itself from its grave, is to ascend a few inches, or even feet, up the trunks of trees, at the foot of which their holes appear in the greatest number, or upon the railfences, which are soon thickly sprinkled with them. In these positions they straightway fix themselves firmly by their barbed claws. Half an hour's observation will then shew you the next change which is to be undergone. A split takes place upon the shell down from the back of the head to the commencement of the rings of the abdomen, and the labour of self-extrication follows. With many a throe and many a strain you see the tail and hind-legs appear through the rent, then the wings extricate themselves painfully from a little case in the outer shell, in which they lie exquisitely folded up, but do not yet unfurl themselves; and, lastly, the head, with its antennæ, disengages itself, and you behold before you the new-born insect freed from its prison. The slough is not disengaged,

but remains firmly fixed in the fibres of the wood, and the insect languidly crawling a few inches, remains as it were in a doze of wonder and astonishment. It is rather under an inch in length, and appears humid and tender; the colours are dull, the eye glazed, the legs feeble, and the wings for awhile after they are opened, appear crumpled and inelastic. All this passes before the sun has gained his full strength. As the day advances, the colours of the insect become more lively, the wings attain their full stretch, and the body dries and is braced up for its future little life of activity and enjoyment.

'Between ten and eleven, the newly-risen tribes begin to tune their instruments. You become conscious of a sound filling the air far and wide, different from the ordinary ones which may meet your ear. A low distinct hum salutes you, turn where you will. It may be compared to the simmering of an enormous caldron; it swells imperceptibly, changes its character, and becomes fuller and sharper. Thousands seem to join in; and by an hour after mid-day, the whole country, far and wide, rings with the unwonted sound. The insects are now seen lodged in or flying about the foliage above, a few hours having been thus sufficient to give them full strength and activity, and bring them into full voice. Well may the school-boy and curly-headed negro rejoice at the sound, for their hands will never want a plaything for many days to come. Well may the birds of the forest rejoice, for this is the season of plenty for them. The pigs and poultry, too, they fatten on the innumerable swarms which before many days will cover the ground in the decline of their strength. The pretty insect-for it is truly such-with its dark body, red eyes, and its glossy wings, interlaced by bright-yellow fibres, enjoys but a little week; and that merry harping which pervades creation from sunrise till sundown for the time of its continuance, is but of some six days' duration. Its character would be almost impossible to describe, though it rings in my ears every time I think of the insect. Like all those of its tribe, the sound produced is not a voice, but a strong vibration of

musical chords, produced by the action of internal muscles upon a species of lyre or elastic membrane covered with net-work, and situated under the wings, the action of which I have often witnessed. The female insect may utter a faint sound, but how, I do not know; it is the male who is endowed with the powerful means of instrumentation which I have described. Though the sound is generally even and continuous as long as the insect is uninterrupted, yet there is a droll variety observable at times; but what it expresses, whether peculiar satisfaction or jealousy, or what other passion, I cannot divine. It has been well described by the word Pha-ro! the first syllable being long and sustained, and connected with the second, which is pitched nearly an octave lower by a drawling smorzando descent. During the whole period of their existence, the closest attention does not detect their eating anything; and with the exception of the trifling injury received by trees consequent upon the process observed by the female in laying her eggs, they are perfectly innoxious. The end to which they seem to be sent to the upper day, is purely confined to the propagation of their species. A few days after their first appearance, the female begins to lay her eggs. She is furnished with an ovipositor situated in a sheath on the abdomen, composed of two serrated hard parallel spines, which she has the power of working with an alternate perpendicular motion. When her time comes, she selects one of the outermost twigs of the forest trees or shrubs, and sets to work, and makes a series of longitudinal jagged incisions in the tender bark and wood. In each of these she lays a row of tiny eggs, and then goes to work again. Having deposited to the heart's content, she crawls up the twig a few inches yet further from the termination, and placing herself in a fitting position, makes two or three perpendicular casts into the very pith. The duty is now terminated. Both male and female become weak, the former ceases to be tuneful: the charm of their existence is at an end; they pine away, become blind, fall to the ground by myriads, and in ten or fifteen days fter their first appearance, they all perish. Not so,

however, their seeds. The perforated twigs die; the first wind breaks them from the tree, and scatters them upon the ground. The eggs give birth to a number of small grubs, which are thus enabled to attain the mould without injury; and in it they disappear, digging their way down into the bosom of the earth. Year goes after yearsummer after summer; the sun shines in vain to themthey "bide their time!" The recollection of their existence begins to fade-a generation passes away; the surface of the country is altered, lands are reclaimed from the forest, streets are laid out and trampled on for years, houses are built, and pavements hide the soil-still, though man may almost forget their existence, God does not. What their life is in the long interval, none can divine. Traces of them have been found in digging wells and foundations eight and ten feet under the surface. When seventeen years have gone by, the memory of them returns, and they are expected. A cold wet spring may retard their appearance, but never since the attention of man has been directed to them, have they failed; but at the appointed time, by one common impulse, they rise from the earth, piercing their way through the matted sod, through the hard trampled clay of the pathways, through the gravel, between the joints of the stones and pavements, and into the very cellars of the houses, like their predecessors, to be a marvel in the land, to sing their blithe song of love and enjoyment under the bright sun, and amidst the verdant landscape-like them, to fulfil the brief duties of their species, and close their mysterious existence by death. We are still children in the small measure of our knowledge and comprehension with regard to the phenomena of the natural world! All things considered, we may venture to prophesy the reappearance of the Cicada Septendecim on the coasts of Maryland and Virginia for the year 1851.'