tribe that have long been celebrated for their musical powers: I mean
the _Cicadiadæ_, including the genera _Fulgora_, _Cicada_, _Tettix_,
and _Tettigonia_[662]. The _Fulgoræ_ appear to be night-singers,
while the _Cicadæ_ sing usually in the day. The great lantern-fly
(_Fulgora laternaria_), from its noise in the evening--nearly
resembling the sound of a cymbal, or razor-grinder when at work--is
called _Scare-sleep_ by the Dutch in Guiana. It begins regularly at
sun-set[663]. Perhaps an insect mentioned by Ligon as making a great
noise in the night in Barbadoes, may belong to this tribe. "There is
a kind of animal in the woods," says he, "that I never saw, which lie
all day in holes and hollow trees, and as soon as the sun is down
begin their tunes, which are neither singing nor crying, but the
shrillest voices I ever heard: nothing can be so nearly resembled to
it as the mouths of a pack of small beagles at a distance; and so
lively and chirping the noise is, as nothing can be more delightful
to the ears, if there were not too much of it; for the music hath no
intermission till morning, and then all is husht[664]."
The species of the other genus, _Cicada_, called by the ancient
Greeks--by whom they were often kept in cages for the sake of their
song--_Tettix_, seem to have been the favourites of every Grecian
bard from Homer and Hesiod to Anacreon and Theocritus. Supposed
to be perfectly harmless, and to live only upon the dew, they
were addressed by the most endearing epithets, and were regarded
as all but divine. One bard entreats the shepherds to spare the
innoxious Tettix, that nightingale of the Nymphs, and to make those
mischievous birds the thrush and blackbird their prey. Sweet prophet
of the summer, says Anacreon, addressing this insect, the Muses
love thee, Phœbus himself loves thee, and has given thee a shrill
song; old age does not wear thee out; thou art wise, earth-born,
musical, impassive, without blood; thou art almost like a god[665].
So attached were the Athenians to these insects, that they were
accustomed to fasten golden images of them in their hair, implying at
the same time a boast that they themselves, as well as the Cicadæ,
were _Terræ filii_. They were regarded indeed by all as the happiest
as well as the most innocent of animals--not, we will suppose, for
the reason given by the saucy Rhodian Xenarchus, when he says,
"Happy the Cicadas' lives,
Since they all have voiceless wives."
If the Grecian _Tettix_ or _Cicada_ had been distinguished by a harsh
and deafening note, like those of some other countries, it would
hardly have been an object of such affection. That it was not, is
clearly proved by the connexion which was supposed to exist between
it and music. Thus the sound of this insect and of the harp were
called by one and the same name[666]. A Cicada sitting upon a harp
was a usual emblem of the science of music, which was thus accounted
for:--When two rival musicians, Eunomus and Ariston, were contending
upon that instrument, a Cicada flying to the former and sitting upon
his harp, supplied the place of a broken string, and so secured to
him the victory[667]. To excel this animal in singing seems to have
been the highest commendation of a singer; and even the eloquence
of Plato was not thought to suffer by a comparison with it[668]. At
Surinam the noise of the _Cicada Tibicen_ is still supposed so much
to resemble the sound of a harp or lyre, that they are called there
harpers (_Lierman_)[669]. Whether the Grecian Cicadæ maintain at
present their ancient character for music, travellers do not tell us.
Those of other countries, however, have been held in less estimation
for their powers of song; or rather have been execrated for the
deafening din that they produce. Virgil accuses those of Italy of
bursting the very shrubs with their noise[670]; and Sir J. E. Smith
observes that this species, which is very common, makes a most
disagreeable dull chirping[671]. Another, _Cicada septendecim_--which
fortunately, as its name imports, appears only once in seventeen
years--makes such a continual din from morning to evening that
people cannot hear each other speak. They appear in Pennsylvania
in incredible numbers in the middle of May[672].--"In the hotter
months of summer," says Dr. Shaw, "especially from midday to the
middle of the afternoon, the Cicada, τεττιξ, or grasshopper, as we
falsely translate it, is perpetually stunning our ears with its most
excessively shrill and ungrateful noise. It is in this respect
the most troublesome and impertinent of insects, perching upon a
twig and squalling sometimes two or three hours without ceasing;
thereby too often disturbing the studies, or short repose that is
frequently indulged, in these hot climates, at those hours. The
τεττιξ of the Greeks must have had a quite different voice, more soft
surely and melodious; otherwise the fine orators of Homer, who are
compared to it, can be looked upon no better than loud loquacious
scolds[673]."--An insect of this tribe, and I am told a very noisy
one, has been found by Mr. Daniel Bydder, before mentioned, in the
New Forest, Hampshire. Previously to this it was not thought that any
of these insect musicians were natives of the British Isles.--Captain
Hancock informs me that the Brazilian Cicadæ sing so loud as to be
heard at the distance of a mile. This is as if a man of ordinary
stature, supposing his powers of voice increased in the ratio of his
size, could be heard all over the world. So that Stentor himself
becomes a mute when compared with these insects.
You feel very curious, doubtless, to know by what means these little
animals are enabled to emit such prodigious sounds. I have lately
mentioned to you the drum of certain grasshoppers; this, however,
appears to be an organ of a very simple structure; but since it is
essential to the economy of the Cicadæ that their males should so
much exceed all other insects in the loudness of their tones, they
are furnished with a much more complex, and indeed most wonderful,
apparatus, which I shall now describe. If you look at the underside
of the body of a male, the first thing that will strike you is a pair
of large plates of an irregular form--in some semi-oval, in others
triangular, in others again a segment of a circle of greater or less
diameter--covering the anterior part of the belly, and fixed to the
trunk between the abdomen and the hind legs[674]. These are the
drum-covers or opercula, from beneath which the sound issues. At the
base of the posterior legs, just above each operculum, there is a small
pointed triangular process (_pessellum_)[675], the object of which,
as Reaumur supposes, is to prevent them from being too much elevated.
When an operculum is removed, beneath it you will find on the exterior
side a hollow cavity, with a mouth somewhat linear, which seems to
open into the interior of the abdomen[676]: next to this, on the inner
side, is another large cavity of an irregular shape, the bottom of
which is divided into three portions; of these the posterior is lined
obliquely with a beautiful membrane, which is very tense--in some
species semi-opake, and in others transparent--and reflects all the
colours of the rainbow. This mirror is not the real organ of sound, but
is supposed to modulate it[677]. The middle portion is occupied by a
plate of a horny substance, placed horizontally and forming the bottom
of the cavity. On its inner side this plate terminates in a carina or
elevated ridge, common to both drums[678]. Between the plate and the
after-breast (_postpectus_) another membrane, folded transversely,
fills an oblique, oblong, or semi-lunar cavity[679]. In some species I
have seen this membrane in tension--probably the insect can stretch or
relax it at its pleasure. But even all this apparatus is insufficient
to produce the sound of these animals;--one still more important and
curious yet remains to be described. This organ can only be discovered
by dissection. A portion of the first and second segments being removed
from that side of the back of the abdomen which answers to the drums,
two bundles of muscles meeting each other in an acute angle, attached
to a place opposite to the point of the mucro of the first ventral
segment of the abdomen, will appear[680]. In Reaumur's specimens
these bundles of muscles seem to have been cylindrical; but in one I
dissected (_Cicada capensis_) they were tubiform, the end to which
the true drum is attached being dilated[681]. These bundles consist
of a prodigious number of muscular fibres applied to each other, but
easily separable. Whilst Reaumur was examining one of these, pulling
it from its place with a pin, he let it go again, and immediately,
though the animal had been long dead, the usual sound was emitted. On
each side of the drum-cavities, when the opercula are removed, another
cavity of a lunulate shape, opening into the interior of the abdomen,
is observable[682]. In this is the true drum, the principal organ of
sound, and its aperture is to the Cicada what our larynx is to us. If
these creatures are unable themselves to modulate their sounds, here
are parts enough to do it for them: for the mirrors, the membranes,
and the central portions, with their cavities, all assist in it. In
the cavity last described, if you remove the lateral part of the first
dorsal segment of the abdomen, you will discover a semi-opaque and
nearly semicircular concavo-convex membrane with transverse folds--this
is the drum[683]. Each bundle of muscles, before mentioned, is
terminated by a tendinous plate nearly circular, from which issue
several little tendons that, forming a thread, pass through an aperture
in the horny piece that supports the drum, and are attached to its
under or concave surface. Thus the bundle of muscles being alternately
and briskly relaxed and contracted, will by its play draw in and let
out the drum: so that its convex surface being thus rendered concave
when pulled in, when let out a sound will be produced by the effort
to recover its convexity; which, striking upon the mirror and other
membranes before it escapes from under the operculum, will be modulated
and augmented by them[684]. I should imagine that the muscular bundles
are extended and contracted by the alternate approach and recession of
the trunk and abdomen to and from each other.
And now, my friend, what adorable wisdom, what consummate art
and skill are displayed in the admirable contrivance and complex
structure of this wonderful, this unparalleled apparatus! The GREAT
CREATOR has placed in these insects an organ for producing and
emitting sounds, which in the intricacy of its construction seems to
resemble that which he has given to man, and the larger animals, for
receiving them. Here is a _cochlea_; a _meatus_; and, as it should
seem, more than one _tympanum_.
I am, &c.
FOOTNOTES:
[600] See above, p. 98.
[601] _Syst. Nat._ 550. 42.
[602] _Nat. Hist._ ii. 254.
[603] White, _Nat. Hist._ ii. 256.
[604] VOL. I. 352--.
[605] Rev. ix. 9.
[606] VOL. I. 113. 146--.
[607] Stedman's _Surinam_, i. 24.
[608] De Geer, vi. 13.
[609] Wiedemann's _Archiv._ ii. 210. 217.
[610] _Act._ i. _Sc._ 2.
[611] Mouffet, 81.
[612] _Linn. Trans._ v. 255. _t._ xii. _f._ 7. b.
[613] Drury's _Insects_, iii. Preface.
[614] Lister's _Gœdart_, 244--. Compare Reaum. vi. 30.
[615] Bingley, _Animal Biogr._ iii. 1st Ed. 335.
[616] See above, p. 41.
[617] _Philos. Trans._ 1781. 48. 38.
[618] _Nat. Hist._ ii. 262.
[619] VOL. I. p. 36.
[620] _Bibl. Nat._ Ed. Hill, i. 125.
[621] Shaw's _Nat. Misc._ iii. 104. _Phil. Trans._ xxxiii. 159.
Compare Dumeril _Traité Element_. ii. 91. n. 694.
[622] Reaum. v. 615. Butler's _Female Monarchy_, c. v. § 4.
[623] See above, p. 147.
[624] Huber, i. 260. ii. 292--.
[625] Reaum. v. 617.
[626] _Philos. Trans._ 1792.
[627] Huber, i. 292--.
[628] Fuessl. _Archiv._ 8. 10.
[629] De Geer, vii. 594.
[630] Rösel, II. 208.
[631] Rai. _Hist. Ins._ 384. Dumeril, _Trait. Element._ ii. 100. n. 17.
[632] De Geer, v. 58. 69. Rösel, II. iii. 5.
[633] Rösel, ibid.
[634] Latr. _Hist. Nat._ x. 264.
[635] De Geer, iii. 289.
[636] _Hist. Ins._ 56.
[637] VOL. I. 34.
[638] _Naturforscher_ Stk. xxi. 77.
[639] III. 16.
[640] Reaum. ii. 290--.
[641] _Nouv. Obs._ ii. 300, note *.
[642] In _Philos. Trans._ 1792.
[643] Schirach, 73--.
[644] i. 226--.
[645] Aristot. _Hist. Anim._ l. v. c. 30. Plin. _Hist. Nat._ l. xi.
c. 26.
[646] Oliv. _Entomol._ i. Pref. ix.
[647] Sparrman, _Voy._ i. 312.
[648] PLATE XXIX. FIG. 13.
[649] Compare De Geer, iii. 512.
[650] De Geer, iii. 517. See also White, _Nat. Hist._ ii. 76;--and
Rai. _Hist. Ins._ 63.
[651] Mouffet, 136.
[652] Goldsmith's _Animat. Nat._ vi. 28.
[653] _Ins. Theatr._ 134.
[654] _Nat. Hist._ ii. 73.
[655] _Nat. Hist._ ii. 81.
[656] See Kirby in _Zool. Journ._ p. iv. 429--.
[657] _Linn. Trans._ iv. 51--.
[658] De Greer, iii. 429.
[659] Ibid. 470.
[660] De Geer, iii. 471. _t._ xxiii. _f._ 2. 3.
[661] Osbeck's _Voy._ i. 71.
[662] _Zoolog. Journ._ n. iv. 429--.
[663] Stedman's _Surinam_, ii. 37.
[664] _Hist. of Barbadoes_, 65.
[665] _Epigramm. Delect._ 45. 234.
[666] Gr. τερετισμα.
[667] Mouffet, _Theatr._ 130.
[668] Ἡδνεπους Πλατων, και τεττιξιν ισολαλος.
[669] Merian _Surinam_. 49.
[670] Et cantu querulæ rumpent arbusta cicadæ. _Georg._ iii. 328.
[671] Smith's _Tour_, iii. 95.
[672] Collinson in _Philos. Trans._ 1763. Stoll, _Cigales_, 26.
[673] _Travels_, 2d Ed. 186.
[674] PLATE VIII. FIG. 18. _c._ †. Reaum. v. _t._ xvi. _f._ 5. u u.
[675] PLATE VIII. FIG. 18. _q´´´_. Reaum. _ubi supra_, _t._ xvi. _f._
11. _b._
[676] Reaum. ibid. _f._ 3. _l l._
[677] Ibid. _ubi supra_, _f._ 3. m m.
[678] Ibid. _q. q. c._
[679] Ibid. _n. n._
[680] Reaum. _ubi supr._ _f._ 6. _f f._
[681] Ibid. _f._ 9. _f f._ PLATE VIII. FIG. 19. C´´.
[682] Reaum. _f._ 3. _l._
[683] Ibid. _f._ 6. _t t. f._ 9.
[684] PLATE VIII. FIG. 19. The figure given in this plate does not
show the drums clearly; but the principal object of it was to exhibit
the bundles of muscles, which are of a different form from those in
Reaumur's figures; they are represented at _C´´. C´´._ in connection
with the drums. The mirror is the part directly beneath these bundles.
LETTER XXV.
_ON LUMINOUS INSECTS._
We boast of our candles, our wax-lights, and our Argand lamps,
and pity our fellow-men who, ignorant of our methods of producing
artificial light, are condemned to pass their nights in darkness. We
regard these inventions as the results of a great exertion of human
intellect, and never conceive it possible that other animals are able
to avail themselves of modes of illumination equally efficient; and
are furnished with the means of guiding their nocturnal evolutions
by actual lights, similar in their effect to those which we make
use of. Yet many insects are thus provided. Some are forced to
content themselves with a single candle, not more vivid than the
rush-light which glimmers in the peasant's cottage; others exhibit
two or four, which cast a stronger radiance; and a few can display a
lamp little inferior in brilliancy to some of ours. Not that these
insects are actually possessed of candles and lamps. You are aware
that I am speaking figuratively. But Providence has supplied them
with an effectual substitute--a luminous preparation or secretion,
which has all the advantages of our lamps and candles without their
inconveniences; which gives light sufficient to direct their
motions, while it is incapable of burning; and whose lustre is
maintained without needing fresh supplies of oil or the application
of the snuffers.
Of the insects thus singularly provided, the common glow-worm
(_Lampyris noctiluca_) is the most familiar instance. Who that has
ever enjoyed the luxury of a summer evening's walk in the country,
in the southern parts of our island, but has viewed with admiration
these "stars of the earth and diamonds of the night?" And if, living
like me in a district where it is rarely met with, the first time
you saw this insect, chanced to be, as it was in my case, one of
those delightful evenings which an English summer seldom yields, when
not a breeze disturbs the balmy air, and "every sense is joy," and
hundreds of these radiant worms, studding their mossy couch with mild
effulgence, were presented to your wondering eye in the course of a
quarter of a mile,--you could not help associating with the name of
glow-worm the most pleasing recollections. No wonder that an insect,
which chiefly exhibits itself on occasions so interesting, and whose
economy is so remarkable, should have afforded exquisite images and
illustrations to those poets who have cultivated Natural History.
If you take one of these glow-worms home with you for examination,
you will find that in shape it somewhat resembles a caterpillar, only
that it is much more depressed; and you will observe that the light
proceeds from a pale-coloured patch that terminates the underside
of the abdomen. It is not, however, the larva of an insect, but the
perfect female of a winged beetle, from which it is altogether so
different, that nothing but actual observation could have inferred
the fact of their being the sexes of the same insect. In the course
of our inquiries you will find that sexual differences even more
extraordinary exist in the insect world.
It has been supposed by many that the males of the different species
of _Lampyris_ do not possess the property of giving out any light;
but it is now ascertained that this supposition is inaccurate,
though their light is much less vivid than that of the female. Ray
first pointed out this fact with respect to _L. noctiluca_[685].
Geoffroy also observed that the male of this species has four
small luminous points, two on each of the two last segments of the
belly[686]: and his observation has been recently confirmed by
Müller. This last entomologist, indeed, saw only two shining spots;
but from the insect's having the power of withdrawing them out of
sight so that not the smallest trace of light remains, he thinks
it is not improbable that at times two other points still smaller
may be exhibited, as Geoffroy has described. In the males of _L.
Splendidula_ and of _L. hemiptera_ the light is very distinct, and
may be seen in the former while flying[687].--The females have the
same faculty of extinguishing or concealing their light--a very
necessary provision to guard them from the attacks of nocturnal
birds: Mr. White even thinks that they regularly put it out between
eleven and twelve every night[688]: and they have also the power of
rendering it for a while more vivid than ordinary.
Authors who have noticed the luminous parts of the common female
glow-worm, having usually contented themselves with stating that the
light issues from the three last ventral segments of the abdomen[689];
I shall give you the result of some observations I once made upon
this subject. One evening, in the beginning of July, meeting with two
of these insects, I placed them on my hand. At first their light was
exceedingly brilliant, so as to appear even at the junctions of the
upper or dorsal segments of the abdomen. Soon after I had taken them,
one withdrew its light altogether, but the other continued to shine.
While it did this it was laid upon its back, the abdomen forming an
angle with the rest of its body, and the last or anal segment being
kept in constant motion. This segment was distinguished by two round
and very vivid spots of light; which, in the specimen that had ceased
to shine, were the last that disappeared, and they seem to be the first
parts that become luminous when the animal is disposed to yield its
light. The penultimate and antepenultimate segments each exhibited a
middle transverse band of yellow radiance, terminated towards the trunk
by an obtusely-dentated line; a greener and fainter light being emitted
by the rest of the segment.
Though many of the females of the _Lampyridæ_ are without wings
and even elytra, (in which circumstance they differ from all other
apterous _Coleoptera_,) this is not the case with all. The female of
_Pygolampis_[690] _italica_, a species common in Italy, and which,
if we may trust to the accuracy of the account given by Mr. Waller
in the _Philosophical Transactions_ for 1684, would seem to have
been taken by him in Hertfordshire, is winged: and when a number of
these moving stars are seen to dart through the air in a dark night,
nothing can have a more beautiful effect. Sir J. E. Smith tells us
that the beaus of Italy are accustomed in an evening to adorn the
heads of the ladies with these artificial diamonds, by sticking them
into their hair; and a similar custom, as I have before informed
you[691], prevails amongst the ladies of India.
Besides the different species of the genus _Lampyris_, all of which
are probably more or less luminous, another insect of the beetle
tribe, _Elater noctilucus_, is endowed with the same property,
and that in a much higher degree. This insect, which is called
the fire-fly, and is an inch long, and about one-third of an inch
broad, gives out its principal light from two transparent eye-like
tubercles placed upon the thorax; but there are also two luminous
patches concealed under the elytra, which are not visible except when
the insect is flying, at which time it appears adorned with four
brilliant gems of the most beautiful golden-blue lustre: in fact, the
whole body is full of light, which shines out between the abdominal
segments when stretched. The light emitted by the two thoracic
tubercles alone is so considerable, that the smallest print may be
read by moving one of these insects along the lines; and in the West
India islands, particularly in St. Domingo, where they are very
common, the natives were formerly accustomed to employ these living
lamps, which they called _Cucuij_, instead of candles in performing
their evening household occupations. In travelling at night they used
to tie one to each great toe; and in fishing and hunting required
no other flambeau[692].--Southey has happily introduced this insect
in his "_Madoc_" as furnishing the lamp by which Coatel rescued the
British hero from the hands of the Mexican priests.
"She beckon'd and descended, and drew out
From underneath her vest a cage, or net
It rather might be call'd, so fine the twigs
Which knit it, where, confined, two Fire-flies gave
Their lustre. By that light did Madoc first
Behold the features of his lovely guide."