larvæ of any European moths, as _Catocala pacta_, _Sponsa_, &c.
proposed with this view by Fabricius[650], seems doubtful, though
certainly many of them afford a very strong silk, and might be
readily propagated; and I have now in my possession some thread more
like cotton than silk spun by the larva of a moth, which when I was
a very young entomologist I observed (if my memory does not deceive
me) upon the Euonymus, and from the twigs of which (not the cocoon)
I unwound it. It is even asserted that in Germany a manufacture of
silk from the cocoons of the emperor moth (_Saturnia Pyri?_) has
been established[651]. There seems no question, however, that silk
might be advantageously derived from many native silk-worms in
America. An account is given in the _Philosophical Transactions_
of one found there, whose cocoon is not only heavier and more
productive of silk than that of the common kind, but is so much
stronger that twenty threads will carry an ounce more[652]. Don Luis
Neé observed on _Psidium pomiferum_ and _pyriferum_ ovate nests of
caterpillars eight inches long, of gray silk, which the inhabitants
of Chilpancingo, Tixtala, &c. in America, manufacture into stockings
and handkerchiefs[653]. Great numbers of similar nests of a dense
tissue, resembling Chinese paper, of a brilliant whiteness, and
formed of distinct and separable layers, the interior being the
thinnest and extraordinarily transparent, were observed by Humboldt
in the provinces of Mechoacan and the mountains of Santarosa at a
height of 10,500 feet above the level of the sea, upon the _Arbutus
Madrôno_ and other trees. The silk of these nests, which are the work
of the social caterpillars of a Bombyx (_B. Madrôno_), was an object
of commerce even in the time of Montezuma, and the ancient Mexicans
pasted together the interior layers, which may be written upon
without preparation, to form a white glossy pasteboard. Handkerchiefs
are still manufactured of it in the Intendency of Oaxaca[654]. De
Azara states that in Paraguay a spider, which is found to near the
thirtieth degree of latitude, forms a spherical cocoon (for its eggs)
an inch in diameter, of a yellow silk, which the inhabitants spin on
account of the permanency of the colour[655]. And according to M. B.
de Lozieres, large quantities of a very beautiful silk, of dazzling
whiteness, may be collected from the cocoons even of the Ichneumons
that destroy the larvæ of some moth in the West Indies which feed
upon the indigo and cassada[656].
It is probable, too, that other articles besides silk might be
obtained from the larvæ which usually produce it, particularly
cements and varnishes of different kinds, some hard, others elastic,
from their gum and silk reservoirs, from which it is said the Chinese
procure a fine varnish, and fabricate what is called by anglers
Indian grass[657]. The diminutive size of the animal will be thought
no objection, when we recollect that the very small quantity of
purple dye afforded by the _Purpura_ of the ancients did not prevent
them from collecting it.
* * * * *
I now conclude this long series of letters on the injuries caused
by insects to man, and the benefits which he derives from them; and
I think you will readily admit that I have sufficiently made good
my position, that the study of agents which perform such important
functions in the economy of nature must be worthy of attention. Our
subsequent correspondence will be devoted to the most interesting
traits in their history,--as their affection to their young, their
food and modes of procuring it, habitations, societies, &c.
I am, &c.
FOOTNOTES:
[541] Walpole in Clarke's _Travels_, ii. 187. Even Mr. Boyle speaks
with abhorrence of eating raw oysters. Walton's _Angler_, Life, p. 12.
[542] Baron Humboldt asks (_Person. Narr._ VI. i. 8. note)--"What
are those worms (_Loul_ in Arabic) which Captain Lyon, the fellow
traveller of my brave and unfortunate friend Mr. Ritchie, found in
the pools of the desert of Fezzan, which served the Arabs for food,
and which have the taste of _Caviare_? Are they not insects' eggs
resembling the _Aguautle_, which I saw sold in the markets of Mexico,
and which are collected on the surface of the lakes of Texcuco?"
For this latter fact he refers to the _Gazeta de Litteratura de
Mexico_. 1794. iii. No. 26. p. 201. It appears from this note of the
illustrious traveller that insects are used as food in their _egg_ as
well as their other states.
[543] Herbst and Schönherr call this distinct genus _Rhyncophorus_;
but as this is too near the name of the tribe (_Rhyncophora_), we
have adopted Thunberg's name, altering the termination to distinguish
it from _Cordyle_ a genus of Lizards.
[544] Ælian. _Hist._ l. xiv. c. 13. quoted in Reaum. ii. 343.
[545] _Ins. Sur._ 48.
[546] _Hist. Nat._ l. xvii. c. 24.
[547] _Wisdom of God_, 9th ed. 307. Ray first adopted the opinion
here maintained, that the Cossi were the larvæ of some beetle; but
afterwards, from observing in the caterpillar of _Cossus ligniperda_
a power of retracting its prolegs within the body, he conjectured
that the hexapod larva from Jamaica, (_Prionus damicornis?_) given
him by Sir Hans Sloane, might have the same faculty, and so be the
caterpillar of a Bombyx.
[548] Amoreux has collected the different opinions of entomologists
on the subject of Pliny's Cossus, which has been supposed the larva
of _Cordylia Palmarum_ by Geoffroy; of _Lucanus Cervus_ by Scopoli;
and of _Prionus damicornis_ by Drury. The first and last, being
neither natives of Italy nor inhabiting the oak, are out of the
question. The larvæ of _Lucanus Cervus_ and _Prionus coriarius_,
which are found in the oak as well as in other trees, may each
have been eaten under this name, as their difference would not be
discernible either to collectors or cooks. Amoreux, 154.
[549] Merian _Ins. Sur._ 24.
[550] St. Pierre, _Voy._ 72.
[551] Smeathman, 32.
[552] Reaum. ii. 344.
[553] _Phytol._ 364.
[554] Diod. Sic. l. iii. c. 29. Strabonis _Geog._ l. xvi. &c.
[555] _Hist. Nat._ l. xi. c. 29.
[556] _Travels_, 232.
[557] _Hieroz._ ii. l. 14. c. 7.
[558] Sparrman, i. 367.
[559] _Rev._ ix. 2, 3.
[560] _Hieroz._ ii. l. 4. c. 7. 492.
[561] Pliny, _Hist. Nat._ l. vi. c. 30.
[562] Id. ibid.
[563] Jackson's _Travels in Marocco_, 53. The Rev. R. Sheppard caused
some of our large English grasshopper (_Acrida viridissima_) to be
cooked in the way here recommended, only substituting butter for
vinegar, and found them excellent.
[564] _Travels_, 230.
[565] Hom. _Il._ γ. 150-4.
[566] Arist. _Hist. An._ l. v. c. 30.
[567] Vide Bochart, _Hieroz._ ii. l. 4. c. 7. 491.
[568] _Hist. Nat._ l. xi. c. 26.
[569] P. Collinson in _Phil. Trans._ 1763. n. x.
[570] One species however has been found in Hampshire in the New
Forest. See Samouelle's _Entomologist's Useful Compendium_, _t._ v.
_f._ 2.
[571] Reaum. ii. 341.
[572] Ray's _Letters_, 135.
[573] Sparrman, i. 201.
[574] Sir G. Staunton's _Voy._ iii. 246.
[575] _Phytol._ 364.
[576] Sparrman, i. 363.
[577] Captain Green relates that, in the ceded districts in India,
they place the branches of trees over the nests, and then by means of
smoke drive out the insects; which attempting to fly, their wings are
broken off by the mere touch of the branches.
[578] Smeathman, 31.
[579] _Letters written in a Mahratta Camp in_ 1809.
[580] Knox's _Ceylon_, 25.
[581] Piso, _Ind._ l. v. c. 13. 291.
[582] _Travels in Sweden_, 118.
[583] _Ibid._
[584] Smith's _Introd. to Bot._ 346. Olivier's _Travels_, i. 139.
[585] Reaum. iii. 416.
[586] Scop. _Carniol._ 337. See above, p. 229. note^b.
[587] Lat. _Hist. Nat._ viii. 93.
[588] Sparrman, i. 201.
[589] _Voyage à la recherche de la Perouse_, ii. 240.
[590] Reaum. ii. 342.
[591] Shaw, _Nat. Misc._
[592] _Hist. Nat._ vii. 227.
[593] Rösel, iv. 257.
[594] _Personal Travels_, ii. 205.
[595] For this list of remedies, see Lesser, _L._ ii. 171-3.
[596] Gerbi. The same virtues have been ascribed to _Coccinella
septempunctata_, L.
[597] Latr. _Hist. Nat. des Fourmis_, 48. 134.
[598] Jackson's _Marocco_, 83. Some doubt however attaches to this
statement, from the circumstance of the figure which Mr. Jackson
gives of his beetle (_Dibben Fashook_) being clearly a mere copy of
that of Mr. Bruce's _Zimb_!
[599] Illiger _Mag._ i. 256.
[600] _Hist. Nat._ l. xix. c. 4.
[601] Vol. v. 213.
[602] _Carabus_, Oliv. _Entom._ iii. 69. _t._ iii. _f._ 26. Compare
_Philanthropist_, ii. 210.
[603] Molina's _Chili_, i. 174.
[604] _Ent. Carniol._ 264.
[605] Captain Green was accustomed to put a fire-fly under the glass
of his watch, when he had occasion to rise very early for a march,
which enabled him, without difficulty, to distinguish the hour.
[606] Molina, i. 171, 285.
[607] Latr. _Hist. Nat._ x. 143.
[608] _Encyclop. Insect._ vi. 281. It had better, perhaps, as
compound Trivial Names are bad, be called _Cynips Scriptorum_.
[609] Olivier's _Travels in Egypt_, &c. ii. 64.
[610] The colour communicated by Kermes with alum, the only mordant
formerly employed, is blood red: but Dr. Bancroft found (i. 404.)
that with the solution of tin used with cochineal it is capable of
imparting a scarlet quite as brilliant as that dye, and perhaps more
permanent. At the same time, however, as ten or twelve pounds contain
only as much colouring matter as one of cochineal, the latter at its
ordinary price is the cheapest.
[611] Bochart, _Hierozoic._ ii. l. iv. c. 27. Beckmann's _History
of Inventions_, Engl. Trans. ii. 171-205. Brancroft _on permanent
Colours_. i. 393. See also Parkhurst's _Heb. Lexicon_ under תלע and שנה.
[612] Rai. _Hist. Plant._ i. 401.
[613] Bancroft, i. 401.
[614] Bancroft, i. 413. Reaum. iv. 88.
[615] Humboldt's _Political Essay on New Spain_, iii. 72-9.
[616] Ibid. iii. 64.--Dr. Bancroft estimates the present annual
consumption of cochineal in Great Britain at about 750 bags, or
150,000 lbs.--worth at the present price 375,000_l._
[617] Lesser, _L._ ii. 165.
[618] Bancroft _on permanent Colours_, ii. 20. 49.
[619] Reaum. iii. _Preface_, xxxi.
[620] _Lach. Lapp._ i. 258.
[621] _Trans. of the Soc. of Arts_, xxiii. 411.
[622] Reaum. iii. 95.
[623] _Political Essay_, iii. 62.
[624] _Voyage dans l'Amer. Merid._ i. 162.
[625] Grosier's _China_, i. 439.
[626] Quoted in Southey's _Thalaba_, ii. 166.
[627] _Embassy to China_, i. 400.
[628] _Phil. Trans._ 1794. xxi.
[629] _Voyage dans l'Amer. Merid._ i. 164.
[630] Molina's _Chili_, i. 174.
[631] _Communications to the Board of Agricult._ vii. 286.
[632] Mills _on Bees_, 77.
[633] Latr. in Humboldt and Bonpland, _Recueil d'Observ. de
Zoologie_, &c. (Paris, 1805) 300.
[634] Hill in _Swammerdam_, i. 181, note.
[635] Latr. _ubi supr._ 300.
[636] Knox's _Ceylon_, 25.
[637] _Voy. dans l'Amer. Merid._ i. 162.
[638] M. Latreille appears to have described this bee under the name
of _Apis unicolor_. _Mém. sur les Abeilles_, 8. 39.
[639] Latr. _Hist. Nat._ xiv. 20.
[640] Latr. in Humboldt and Bonpland, _Recueil_, &c. 302.
[641] _Vorlesungen_, 324. I have read somewhere, but neglecting to
make a memorandum I cannot refer to the author, (Latreille?) that a
species of wasp in South America collects and stores up _honey_.
[642] Colebrook in _Asiatic Researches_, v. 61.
[643] Milton's _Comus_.
[644] _Hist. Animal._ l. v. c. 19. A French gentleman, M. Vaucanson,
has invented a mill for unwinding the cocoons of the silkworm.
Scott's _Visit to Paris_, 4th ed. 304.
[645] Pausanias, quoted by Goldsmith, vi. 80.
[646] Pliny _Hist. Nat._ l. xi. c. 22.
[647] Aristot. _ubi supr._ He does not expressly say the _pupa_, but
this we must suppose. The _larva_ he means could not be the common
silk-worm, since he describes it as large, and having as it were horns.
[648] vii. 33-48. Compare Lord Valentia's _Travels_, i. 78.
[649] xxiii. 235.
[650] _Vorlesungen_, 325.
[651] Latr. _Hist. Nat._ xiv. 150. Three modern species of _Saturnia_
were formerly considered as varieties only, and distinguished by the
trivial name of _Pavonia major_, _media_, and _minor_; these are now
called _S. Pyri_, _Spini_, and _Carpini_. Ochsenh.
[652] Pullein in _Phil. Trans._ 1759. 54.
[653] _Annals of Botany_, ii. 104.
[654] _Political Essay on N. Spain_, iii. 59.
[655] _Voyage dans l'Amer. Merid._ i. 212. It may here be observed
as a benefit derived by the higher walks of philosophy from
insects--that astronomers employ the strongest thread of spiders,
the one namely that supports the web, for the divisions of the
micrometer. By its ductility this thread acquires about a fifth of
its ordinary length. _Nouv. Dict. d'Hist. Nat._ ii. 280.
[656] _American Phil. Trans._ v. 325.
[657] Anderson's _Recreations in Agriculture_, &c. iv. 399.
LETTER XI.
_ON THE AFFECTION OF INSECTS FOR
THEIR YOUNG._
Amongst the larger animals, every observer of nature has witnessed,
with admiration, that love of their offspring which the beneficent
Creator, with equal regard to the happiness of the parent and the
progeny, has interwoven in the constitution of his creatures.
Who that has any sensibility, has not felt his heart dilate with
gratitude to the Giver of all good, in observing amongst the domestic
animals which surround him, the effects of this divine _storgé_,
so fruitful of the most delightful sensations? Who that is not a
stock or a stone has read unmoved the anecdote recorded in books of
Natural History, of the poor bitch, which in the agonies of a cruel
dissection licked with parental fondness her new-born offspring; or
the affecting account of the she-bear related in Phipps's _Voyage to
the North Pole_, which, herself severely wounded by the same shot
that killed her cubs, spent her last moments in tearing and laying
before them the food she had collected, and died licking their wounds?
These feelings you must have experienced, but it has scarcely
occurred to you that you would have any room for exercising them
in your new pursuit. You have not, I dare say, suspected that any
similar example could have been adduced amongst _insects_, to which
at the first glance there seems even something absurd in attributing
any thing like parental affection. An animal not so big perhaps as
a grain of wheat, feel love for its offspring--how preposterous!
we are ready to exclaim. Yet the exclamation would be very much
misplaced. Nothing is more certain than that insects are capable of
feeling quite as much attachment to their offspring as the largest
quadrupeds. They undergo as severe privations in nourishing them;
expose themselves to as great risk in defending them; and in the very
article of death exhibit as much anxiety for their preservation.
Not that this can be said of all insects. A very large proportion
of them are doomed to die before their young come into existence.
But in these the passion is not extinguished. It is merely modified,
and its direction changed. And when you witness the solicitude with
which they provide for the security and sustenance of their future
young, you can scarcely deny to them love for a progeny they are
never destined to behold. Like affectionate parents in similar
circumstances, their last efforts are employed in providing for the
children that are to succeed them.
I. Observe the motions of that common white butterfly which you see
flying from herb to herb. You perceive that it is not food she is in
pursuit of; for flowers have no attraction for her. Her object is the
discovery of a plant that will supply the sustenance appropriated by
Providence to her young, upon which to deposit her eggs. Her own food
has been honey drawn from the nectary of a flower. This, therefore, or
its neighbourhood, we might expect would be the situation she would
select for them. But no: as if aware that this food would be to them
poison, she is in search of some plant of the cabbage tribe. But how is
she to distinguish it from the surrounding vegetables? She is taught of
God! Led by an instinct far more unerring than the practised eye of the
botanist, she recognises the desired plant the moment she approaches
it, and upon this she places her precious burthen; yet not without
the further precaution of ascertaining that it is not preoccupied by
the eggs of some other butterfly! Having fulfilled this duty, from
which no obstacle short of absolute impossibility, no danger however
threatening, can divert her, the affectionate mother dies.
This may serve as one instance of the solicitude of insects for
their future progeny. But almost every species will supply examples
similar in principle, and in their particular circumstances even more
extraordinary. In every case (except in some remarkable instances
of mistakes of instinct, as they may be termed, which will be
subsequently adverted to) the parent unerringly distinguishes the
food suitable for her offspring, however dissimilar to her own; or at
least invariably places her eggs, often defended from external injury
by a variety of admirable contrivances, in the exact spot where,
when hatched, the larvæ can have access to it.--The dragon-fly is
an inhabitant of the air, and could not exist in water: yet in this
element, which is alone adapted for her young, she ever carefully
drops her eggs. The larvæ of the gad-fly (_Gasterophilus Equi_),
whose history has been before described to you[658], are destined to
live in the stomach of the horse. How shall the parent, a two-winged
fly, convey them thither? By a mode truly extraordinary. Flying
round the animal, she curiously poises her body for an instant while
she glues a single egg to one of the hairs of his skin, and repeats
this process until she has fixed in a similar way many hundred
eggs. These, after a few days, on the application of the slightest
moisture attended by warmth, hatch into little grubs. Whenever,
therefore, the horse chances to lick any part of his body to which
they are attached, the moisture of the tongue discloses one or more
grubs, which adhering to it by means of the saliva are conveyed into
the mouth, and thence find their way into the stomach. But here a
question occurs to you. It is but a small portion of the horse's
body which he can reach with his tongue: what, you ask, becomes of
the eggs deposited on other parts? I will tell you how the gad-fly
avoids this dilemma; and I will then ask you if she does not discover
a provident forethought, a depth of instinct, which almost casts
into shade the boasted reason of man? She places her eggs only on
those parts of the skin which the horse is able to reach with his
tongue; nay, she confines them almost exclusively to the knee or
the shoulder, which he is sure to lick. What could the most refined
reason, the most precise adaptation of means to an end, do more[659]?
Not less admirable is the parental instinct of that vast tribe of
insects already introduced to you by the name of _Ichneumons_,
whose young are destined to feed upon the living bodies of other
insects. These, as you know, are so numerous, that scarcely an insect
exists, which in its larva state is not exposed to the attacks of
one or other of them; and even the pupæ, nay the very eggs of these
animals, are not safe from their insidious manœuvres. The size of
the different species varies in proportion to that of the bodies
which are to be their food; some being so inconceivably small, that
the egg of a butterfly not bigger than a pin's head is of sufficient
magnitude to nourish two of them to maturity[660]; others so large,
that the body of a full-grown caterpillar is not more than enough for
one. They are the larvæ of these Ichneumons which make such havoc
of our pygmy tribes: the perfect insect is a four-winged fly, which
takes no other food than a little honey; and the great object of
the female is to discover a proper nidus for her eggs. In search of
this she is in constant motion. Is the caterpillar of a butterfly
or moth the appropriate food for her young? You see her alight upon
the plants where they are most usually to be met with, run quickly
over them, carefully examining every leaf, and, having found the
unfortunate object of her search, insert her sting into its flesh
and there deposit an egg. In vain her victim, as if conscious of
its fate, writhes its body, spits out an acid fluid, menaces with
its tentacula, or brings into action the other organs of defence
with which it is provided. The active Ichneumon braves every danger,
and does not desist until her courage and address have ensured
subsistence for one of her future progeny. Perhaps, however, she
discovers, by a sense the existence of which we perceive, though
we have no conception of its nature, that she has been forestalled
by some precursor of her own tribe, that has already buried an
egg in the caterpillar she is examining. In this case she leaves
it, aware that it would not suffice for the support of two, and
proceeds in search of some other yet unoccupied.--The process is of
course varied in the case of those minute species of which several,
sometimes as many as 150, can subsist in a single caterpillar. The
little Ichneumon then repeats her operations until she has darted
into her victim the requisite number of eggs.
The larvæ hatched from the eggs thus ingeniously deposited, find
a delicious banquet in the body of the caterpillar, which is sure
eventually to fall a victim to their ravages. So accurately,
however, is the supply of food proportioned to the demand, that this
event does not take place until the young Ichneumons have attained
their full growth: when the caterpillar either dies, or, retaining
just vitality enough to assume the pupa state, then finishes its
existence; the pupa disclosing not a moth or a butterfly, but one or
more full-grown Ichneumons.
In this strange and apparently cruel operation one circumstance is
truly remarkable. The larva of the Ichneumon, though every day,
perhaps for months, it gnaws the inside of the caterpillar, and
though at last it has devoured almost every part of it except the
skin and intestines, carefully all this time _avoids injuring the
vital organs_, as if aware that its own existence depends on that of
the insect on which it preys! Thus the caterpillar continues to eat,
to digest, and to move, apparently little injured, to the last, and
only perishes when the parasitic grub within it no longer requires
its aid. What would be the impression which a similar instance
amongst the race of quadrupeds would make upon us?--If, for example,
an animal--such as some impostors have pretended to carry within
them--should be found to feed upon the inside of a dog; devouring
only those parts not essential to life, while it cautiously left
uninjured the heart, arteries, lungs, and intestines,--should we
not regard such an instance as a perfect prodigy, as an example of
instinctive forbearance almost miraculous?
Some Ichneumons, instead of burying their eggs in the body of the larvæ
that are to serve their young for food, content themselves with gluing
them to the skin of their prey, which the young grubs pierce as soon
as hatched. Another tribe, whose activity and perseverance are equally
conspicuous, which includes the beautiful genus _Chrysis_ and many
other hymenopterous insects, imitating the insidious cuckoo, contrive
to introduce their eggs into the nests in which bees and other insects
have deposited theirs. With this view they are constantly on the watch,
and, the moment the unsuspecting mother has quitted her cell for the
purpose of collecting a store of food or materials, glide into it and
leave an egg, the germe of a future assassin of the larva that is to
spring from that deposited by its side.
The females of the insects of which we have been speaking, in providing
for their offspring, are saved the trouble of furnishing them with
any habitation. Either they occupy that of another insect, or find a
convenient abode within the body of that on which they feed. But upon
the maternal affection of another large hymenopterous tribe, belonging
to Latreille's Family of Burrowers (_Fossores_), whose young in like
manner feed on other insects, is imposed the arduous task not merely of
collecting a supply of food, but of inclosing it along with their eggs
in cells or burrows often of considerable depth, and dug with great
labour in sand or the solid earth.