The beautiful poetical imagery with which Mr. Southey has decorated this and a few other entomological facts, will make you join in my regret that a more extensive acquaintance with the science has not enabled him to spread his embellishments over a greater number. The gratification which the entomologist derives from seeing his favourite study adorned with the graces of poetry is seldom unalloyed with pain, arising from the inaccurate knowledge of the subject in the poet. Dr. Darwin's description of the beetle to which the nut-maggot is transformed may delight him (at least if he be an admirer of the Darwinian style) as he reads for the first time,
"So sleeps in silence the Curculio, shut
In the dark chamber of the cavern'd nut;
Erodes with ivory beak the vaulted shell,
And quits on filmy wings its narrow cell."
But when the music of the lines has allowed him room for pause, and he recollects that they are built wholly upon an incorrect supposition, the Curculio never inhabiting the nut in its beetle shape, nor employing its ivory or rather ebony beak upon it, but undergoing its transformation under ground, he feels disappointed that the passage has not truth as well as sound.—Mr. Southey, too, has fallen into an error: he confounds the fire-fly of St. Domingo (Elater noctilucus) with a quite different insect, the lantern-fly (Fulgora laternaria) of Madame Merian; but happily this error does not affect his poetry.
But to return from this digression.—If we are to believe Mouffet, (and the story is not incredible,) the appearance of the tropical fire-flies on one occasion led to a more important result than might have been expected from such a cause. He tells us, that when Sir Thomas Cavendish and Sir Robert Dudley first landed in the West Indies, and saw in the evening an infinite number of moving lights in the woods, which were merely these insects, they supposed that the Spaniards were advancing upon them, and immediately betook themselves to their ships[696]:—a result as well entitling the Elaters to a commemoration feast, as a similar good office the land-crabs of Hispaniola, which, as the Spaniards tell, (and the story is confirmed by an anniversary Fiesta de lôs Cangrejos,) by their clattering—mistaken by the enemy for the sound of Spanish cavalry close upon their heels—in like manner scared away a body of English invaders of the city of St. Domingo[697].
An anecdote less improbable, perhaps, and certainly more ludicrous, is related by Sir J. E. Smith of the effect of the first sight of the Italian glow-worms upon some Moorish ladies ignorant of such appearances. These females had been taken prisoners at sea, and, until they could be ransomed, lived in a house in the outskirts of Genoa, where they were frequently visited by the respectable inhabitants of the city; a party of whom, on going one evening, were surprised to find the house closely shut up, and their Moorish friends in the greatest grief and consternation. On inquiring into the cause, they ascertained that some of the Pygolampis italica had found their way into the dwelling, and that the ladies within had taken it into their heads that these brilliant guests were no other than the troubled spirits of their relations; of which idea it was some time before they could be divested.—The common people in Italy have a superstition respecting these insects somewhat similar, believing that they are of a spiritual nature, and proceed out of the graves, and hence carefully avoid them[698].
The insects hitherto adverted to have been beetles, or of the order Coleoptera. But besides these, a genus in the order Hemiptera, called Fulgora, includes several species which emit so powerful a light as to have obtained in English the generic appellation of Lantern-flies. Two of the most conspicuous of this tribe are the F. laternaria and F. candelaria; the former a native of South America, the latter of China. Both, as indeed is the case with the whole genus, have the material which diffuses their light included in a hollow subtransparent projection of the head. In F. candelaria this projection is of a subcylindrical shape, recurved at the apex, above an inch in length, and the thickness of a small quill. We may easily conceive, as travellers assure us, that a tree studded with multitudes of these living sparks, some at rest and others in motion, must at night have a superlatively splendid appearance.—In F. laternaria, which is an insect two or three inches long, the snout is much larger and broader, and more of an oval shape, and sheds a light the brilliancy of which transcends that of any other luminous insect. Madame Merian informs us, that the first discovery which she made of this property caused her no small alarm. The Indians had brought her several of these insects, which by day-light exhibited no extraordinary appearance, and she inclosed them in a box until she should have an opportunity of drawing them, placing it upon a table in her lodging-room. In the middle of the night the confined insects made such a noise as to awake her, and she opened the box, the inside of which to her great astonishment appeared all in a blaze; and in her fright letting it fall, she was not less surprised to see each of the insects apparently on fire. She soon, however, divined the cause of this unexpected phenomenon, and re-inclosed her brilliant guests in their place of confinement. She adds, that the light of one of these Fulgoræ is sufficiently bright to read a newspaper by: and though the tale of her having drawn one of these insects by its own light is without foundation, she doubtless might have done so if she had chosen[699].—Another species (F. pyrrhorynchus) is figured by Mr. Donovan in his Insects of India, of which the light, though from a smaller snout than that of F. laternaria, must assume a more splendid and striking appearance, the projection being of a rich deep purple from the base to near the apex, which is of a fine transparent scarlet; and these tints will of course be imparted to the transmitted light.
In addition to the insects already mentioned, some others have the power of diffusing light, as two species of Centipedes (Geophilus electricus and phosphoreus), and probably others of the same genus. In these the light is not confined to one part, but proceeds from the whole body. G. electricus is a common insect in this country, residing under clods of earth, and often visible at night in gardens. G? phosphoreus, a native of Asia, is an obscure species, described by Linné, on the authority of C. G. Ekeberg, the captain of a Swedish East Indiaman, who asserted that it dropped from the air, shining like a glow-worm, upon his ship, when sailing in the Indian ocean a hundred miles (Swedish) from the continent. However singular this statement, it is not incredible. The insect may either, as Linné suspects, have been elevated into the atmosphere by wings with which, according to him, one species of the genus is provided; or more probably, perhaps, by a strong wind, such as that which raised into the air the shower of insects mentioned by De Geer as occurring in Sweden in the winter of 1749, after a violent storm that had torn up trees by the roots, and carried away to a great distance the surrounding earth, and insects which had taken up their winter quarters amongst it[700]. That the wind may convey the light body of an insect to the above-mentioned distance from land, you will not dispute when you call to mind that our friend Hooker, in his interesting Tour in Iceland, tells us that the ashes from the eruption of one of the Icelandic volcanos in 1755 were conveyed to Ferrol, a distance of upwards of 300 miles[701].—Lastly, to conclude my list of luminous insects, Professor Afzelius observed "a dim phosphoric light" to be emitted from the singular hollow antennæ of Pausus sphærocerus[702]. A similar appearance has been noticed in the eyes of Acronycta Psi, Cossus ligniperda, and other moths. Chiroscelis bifenestrata of Lamarck, a beetle, has two red oval spots covered with a downy membrane on the second segment of the abdomen, which he thinks indicate some particular organ perhaps luminous[703]: and M. Latreille informs me that a friend of his, who saw one living which was brought from China to the Isle of France in wood, found that the ocelli in the elytra of Buprestis ocellata were luminous.
But besides the insects here enumerated, others may be luminous which have not hitherto been suspected of being so. This seems proved by the following fact. A learned friend[704] has informed me, that when he was curate of Ickleton, Cambridgeshire, in 1780, a farmer of that place of the name of Simpringham brought to him a mole-cricket (Gryllotalpa vulgaris, Latr.), and told him that one of his people, seeing a Jack-o'lantern, pursued it and knocked it down, when it proved to be this insect, and the identical specimen shown to him.
This singular fact, while it renders it probable that some insects are luminous which no one has imagined to be so, seems to afford a clue to the, at least, partial explanation of the very obscure subject of ignes fatui, and to show that there is considerable ground for the opinion long ago maintained by Ray and Willughby, that the majority of these supposed meteors are no other than luminous insects. That the large varying lambent flames, mentioned by Beccaria to be very common in some parts of Italy, and the luminous globe seen by Dr. Shaw[705] cannot be thus explained, is obvious. These were probably electrical phenomena: certainly not explosions of phosphuretted hydrogene, as has been suggested by some, which must necessarily have been momentary. But that the ignis fatuus mentioned by Derham as having been seen by himself, and which he describes as flitting about a thistle[706], was, though he seems of a different opinion, no other than some luminous insect, I have little doubt. Mr. Sheppard informs me that, travelling one night between Stamford and Grantham on the top of the stage, he observed for more than ten minutes a very large ignis fatuus in the low marshy grounds, which had every appearance of being an insect. The wind was very high: consequently, had it been a vapour, it must have been carried forward in a direct line; but this was not the case. It had the same motions as a Tipula, flying upwards and downwards, backwards and forwards, sometimes appearing as settled, and sometimes as hovering in the air.—Whatever be the true nature of these meteors, of which so much is said and so little known, it is singular how few modern instances of their having been observed are on record. Dr. Darwin declares, that though in the course of a long life he had been out in the night, and in the places where they are said to appear, times without number, he had never seen any thing of the kind: and from the silence of other philosophers of our own times, it should seem that their experience is similar.