noxious insect, still in many cases, without further information, he
may fall short of his purpose of prevention. Thus we are told that
in Germany the gardeners and country people, with great industry,
gather whole baskets full of the caterpillar of the destructive
cabbage moth (_Mamestra Brassicæ_), and then bury them, which, as
Roesel well observes[57], is just as if we should endeavour to kill
a crab by covering it with water; for, many of them being full grown
and ready to pass into their next state, which they do underground,
instead of destroying them by this manœuvre, their appearing again
the following year in greater numbers is actually facilitated. Yet
this plan applied to our common cabbage caterpillar, which does
not go underground, would succeed. So that some knowledge of the
manners of an insect is often requisite to enable us to check its
ravages effectually. With respect to noxious caterpillars in general,
agriculturists and gardeners are not usually aware that the best mode
of preventing their attacks is to destroy the female fly before she
has laid her eggs, to do which the moth proceeding from each must be
first ascertained. But if their research were carried still further,
so as to enable them to distinguish the pupa and discover its haunts,
and it would not be at all difficult to detect that of the greatest
pest of our gardens, the cabbage butterfly, the work might be still
more effectually accomplished. Some larvæ are polyphagous, or feed
upon a variety of plants; amongst others that of the yellow-tail
moth (_Arctia chrysorhœa_); yet gardeners think they have done
enough if they destroy the web-like nests which so often deform our
fruit-trees, without suspecting that new armies of assailants will
wander from those on other plants which they have suffered to remain.
Thus will thousands be produced in the following season, which, had
they known how to distinguish them, might have been extirpated.
Another instance occurred to me last year, when walking with a
gentleman in his estate at a village in Yorkshire. Our attention was
attracted by several circular patches of dead grass, each having a
stick with rags suspended to it, placed in the centre. I at once
discerned that the larva of the cock-chafer had eaten the roots
of the grass, which being pulled up by the rooks that devour this
mischievous grub, these birds had been mistaken by the tenant for
the cause of the evil, and the rags were placed to frighten away his
best friends. On inquiry why he had set up these sticks, he replied,
"He could n't beer to see'd nasty craws pull up all'd gess, and sae
he'd set'd bairns to hing up some aud clouts to flay 'em away. Gin
he'd letten 'em alean they'd sean hev reated up all'd close." Nor
could I convince him by all that I could say, that the rooks were not
the cause of the evil. Even philosophers sometimes fall into gross
mistakes from this species of ignorance. Dr. Darwin has observed,
that destroying the beautiful but injurious woodpeckers is the only
alternative for preventing the injury they do to our forest-trees by
boring into them[58]; not being aware that they bore only those trees
which insects have previously attacked, and that they diminish very
considerably the number of such as are prejudicial to our forests.
From these facts it is sufficiently evident that entomological
knowledge is necessary both to prevent fatal mistakes, and to enable
us to check with effect the ravages of insects. But ignorance in
this respect is not only unfit to remedy the evil; on the contrary,
it may often be regarded as its cause. A large proportion of the
most noxious insects in every country are not indigenous, but have
been imported. It was thus that the moth (_Galleria Mellonella_) so
destructive in bee-hives, and the asparagus beetle (_Lema Asparagi_)
were made denizens of Sweden[59]. The insect that has destroyed all
the peach-trees in St. Helena was imported from the Cape: and at
home (not to mention bugs and cock-roaches) the great pest of our
orchards, before mentioned, the apple Aphis, there is good reason to
believe, was introduced with some foreign apple-trees. Now, extensive
as is our commerce, it is next to impossible, by any precautions, to
prevent the importation of these noxious agents. A cargo, or even a
sample, of peas from North America might present us with that ravager
of pulse, the pea-beetle (_Bruchus Pisi_); or the famed Hessian fly,
which some years ago caused such trepidation in our cabinet, might
be conveyed here in a ship-load of wheat. Leeuwenhoek's wolf (_Tinea
granella_) might visit us, in a similar conveyance, from Holland
or France. But though introduced, were Entomology a more general
pursuit, their presence would soon be detected, and the evil at once
nipt in the bud; whereas in a country where this science was not at
all or little cultivated, they would most probably have increased to
such an extent before they attracted notice, that every effort to
extirpate them would be ineffectual.
It is needless to insist upon the importance of the study of insects,
as calculated to throw light upon some of the obscurest points of
general physiology; nor would it be difficult, though the task might
be invidious, to point out how grossly incorrect and deficient are
many of the speculations of our most eminent philosophers, solely
from their ignorance of this important branch of Natural History. How
little qualified would that physiologist be to reason conclusively upon
the mysterious subject of generation, who should be ignorant of the
wonderful and unlooked-for fact, brought to light by the investigations
of an entomologist, that one sexual intercourse is sufficient to
fertilize the eggs of numerous generations of Aphides! And how
defective would be all our reasonings on the powers of nutrition and
secretion, had we yet to learn that in insects both are in action
unaccompanied by the circulating system and glands of larger animals!
In another point of view entomological information is very useful.
A great deal of unnecessary mischief is produced, and unnecessary
uneasiness occasioned, by what are called vulgar errors, and that
superstitious reliance upon charms, which prevents us from having
recourse to remedies that are really efficacious. Thus, for instance,
eating figs and sweet things has been supposed to generate lice[60].
Nine larvæ of the moth of the wild teasel inclosed in a reed or goose
quill have been reckoned a remedy for ague[61]. Matthiolus gravely
affirms that every oak-gall contains either a fly, a spider, or a
worm; and that the first foretells war, the second pestilence, and
the third famine[62]. In Sweden the peasants look upon the grub of
the cock-chafer as furnishing an unfailing prognostic whether the
ensuing winter will be mild or severe; if the animal have a blueish
hue (a circumstance which arises from its being replete with food)
they affirm it will be mild, but on the contrary if it be white the
weather will be severe: and they carry this so far as to foretell,
that if the anterior part be white and the posterior blue, the cold
will be most severe at the beginning of the winter. Hence they call
this grub _Bemärkelse-mask_, or prognostic worm[63]. A similar augury
as to the harvest is drawn by the Danish peasants from the mites
which infest the common dung beetle (_Geotrupes stercorarius_),
called in Danish _Skarnbosse_ or _Torbist_. If there are many of
these mites between the fore feet, they believe that there will be
an early harvest, but a late one if they abound between the hind
feet[64]. The appearance of the death's head hawk-moth (_Acherontia
Atropos_) has in some countries produced the most violent alarm and
trepidation amongst the people, who, because it emits a plaintive
sound, and is marked with what looks like a death's head upon its
back, regarded it as the messenger of pestilence and death[65]. We
learn from Linné that a similar superstition, built upon the black
hue and strange aspect of that beetle, prevails in Sweden with
respect to _Blaps mortisaga_, L.[66]; and in Barbadoes, according to
Hughes, the ignorant deem the appearance of a certain grasshopper in
their houses as a sure presage of illness to some of the family[67].
One would not think that the excrements of insects could be objects
of terror, yet so it has been. Many species of _Lepidoptera_,
when they emerge from the pupa state, discharge from their anus
a reddish fluid, which, in some instances, where their numbers
have been considerable, has produced the appearance of a shower of
blood; and by this natural fact, all those bloody showers, recorded
by historians as preternatural, and regarded where they happened
as fearful prognostics of impending evils, are stripped of their
terrors, and reduced to the class of events that happen in the
common course of nature. That insects are the cause of these showers
is no recent discovery; for Sleidan relates that in the year 1553
a vast multitude of butterflies swarmed through a great part of
Germany, and sprinkled plants, leaves, buildings, clothes and men,
with bloody drops, as if it had rained blood[68]. But the most
interesting account of an event of this kind is given by Reaumur,
from whom we learn that in the beginning of July 1608 the suburbs
of Aix, and a considerable extent of country round it, were covered
with what appeared to be a shower of blood. We may conceive the
amazement and stupor of the populace upon such a discovery, the alarm
of the citizens, the grave reasonings of the learned. All agreed
however in attributing this appearance to the powers of darkness,
and in regarding it as the prognostic and precursor of some direful
misfortune about to befall them. Fear and prejudice would have taken
deep root upon this occasion, and might have produced fatal effects
upon some weak minds, had not M. Peiresc, a celebrated philosopher of
that place, paid attention to insects. A chrysalis which he preserved
in his cabinet, let him into the secret of this mysterious shower.
Hearing a fluttering, which informed him his insect was arrived at
its perfect state, he opened the box in which he kept it. The animal
flew out and left behind it a red spot. He compared this with the
spots of the bloody shower, and found they were alike. At the same
time he observed there was a prodigious quantity of butterflies
flying about, and that the drops of the miraculous rain were not
to be found upon the tiles, nor even upon the upper surface of the
stones, but chiefly in cavities and places where rain could not
easily come. Thus did this judicious observer dispel the ignorant
fears and terror which a natural phenomenon had caused[69].
The same author relates an instance of the gardener of a gentleman
being thrown into a horrible fright by digging up some of the curious
cases, which I shall hereafter describe to you, of the leaf-cutter
bees, and which he conceived to be the effect of witchcraft
portending some terrible misfortune. By the advice of the priest
of the parish he even took a journey from Rouen to Paris, to show
them to his master: but he, happily having more sense than the man,
carried them to M. Nollet, an eminent naturalist, who having seen
similar productions was aware of the cause, and opening one of the
cases, while the gardener stood aghast at his temerity, pointed out
the grub that it contained, and thus sent him back with a light
heart, relieved from all his apprehensions[70].
Every one has heard of the death-watch, and knows of the
superstitious notion of the vulgar, that in whatever house its drum
is heard one of the family will die before the end of the year. These
terrors, in particular instances, where they lay hold of weak minds,
especially of sick or hypochondriac persons, may cause the event that
is supposed to be prognosticated. A small degree of entomological
knowledge would relieve them from all their fears, and teach them
that this heart-sickening tick is caused by a small beetle (_Anobium
tessellatum_) which lives in timber, and is merely a call to its
companion. Attention to Entomology may therefore be rendered very
useful in this view, since nothing certainly is more desirable than
to deliver the human mind from the dominion of superstitious fears,
and false notions, which having considerable influence on the conduct
of mankind are the cause of no small portion of evil.
But as we cannot well guard against the injuries produced by insects,
or remove the evil, whether real or arising from misconceptions
respecting them, which they occasion, unless we have some knowledge
of them; so neither without such knowledge can we apply them, when
beneficial, to our use. Now it is extremely probable that they might
be made vastly more subservient to our advantage and profit than at
present, if we were better acquainted with them. It is the remark of
an author, who himself is no entomologist: "We have not taken animals
enough into alliance with us. The more spiders there were in the
stable, the less would the horses suffer from the flies. The great
American fire-fly should be imported into Spain to catch mosquitos. In
hot countries a reward should be offered to the man who could discover
what insects feed upon fleas[71]." It would be worth our while to act
upon this hint, and a similar one of Dr. Darwin. Those insects might
be collected and preserved that are known to destroy the Aphides and
other injurious tribes; and we should thus be enabled to direct their
operations to any quarter where they would be most serviceable; but
this can never be done till experimental agriculturists and gardeners
are conversant with insects, and acquainted with their properties
and economy. How is it that the Great Being of beings preserves the
system which he has created from permanent injury, in consequence of
the too great redundancy of any individual species, but by employing
one creature to prey upon another, and so overruling and directing
the instincts of all, that they may operate most where they are most
wanted! We cannot better exercise the reasoning powers and faculties
with which he has endowed us, than by copying his example. We often
employ the larger animals to destroy each other, but the smaller,
especially insects, we have totally neglected. Some may think, perhaps,
that in aiming to do this we should be guilty of presumption, and of
attempting to take the government and direction of things out of the
hands of Providence: but this is a very weak argument, which might
with equal reason be adduced to prove that when rats and mice become
troublesome to us, we ought not to have recourse to dogs, ferrets, and
cats to exterminate them. When any species multiplies upon us, so as
to become noxious, we certainly have a just right to destroy it, and
what means can be more proper than those which Providence itself has
furnished? We can none of us go further or do more than the Divine Will
permits; and he will take care that our efforts shall not be injurious
to the general welfare, or effect the annihilation of any individual
species.
Again, with regard to insects that are employed in medicine or
the arts, if the apothecary cannot distinguish a Cantharis or
blister-beetle from a Carabus or Cetonia, both of which beetles I have
found mixed with the former, how can he know whether his druggist
furnishes him with a good or bad article? And the same observation
may with still greater force apply to the dyer in his purchase of
cochineal, since it is still more difficult to distinguish the wild
sort from the cultivated. There are, it is probable, many insects
that might be employed with advantage in both these departments: but
unless Entomology be more generally studied by scientific men, who are
the only persons likely to make discoveries of this kind, than it has
hitherto been, we must not hope to derive further profit from them.
It seems more particularly incumbent upon the professors of the divine
art of healing to become conversant with this as well as the other
branches of Natural History; for not only do they derive some of their
most useful drugs from insects, but many also of the diseases upon
which they are consulted, as we shall see hereafter, are occasioned by
them. For want of this kind of information medical men run the risk
of confounding diseases perfectly distinct, at least as to the animal
that causes them. It would be a most desirable thing to have professors
in each branch of Natural History in our universities, and to make
it indispensable, in order to the obtaining of any degree in Physic,
that the candidate should have attended these lectures. We may judge
from the good effects that the arts have derived from the present very
general attention to Chemistry, how beneficial would be the consequence
if Entomology were equally cultivated: and I shall conclude this
paragraph with what I think may be laid down as an incontrovertible
axiom:--That the profit we derive from the works of creation will
be in proportion to the accuracy of our knowledge of them and their
properties.
I trust I have now said enough to convince you and every thinking man
that the study of insects, so far from being vain, idle, trifling,
or unprofitable, may be attended with very important advantages to
mankind, and ought at least to be placed upon a level with many other
branches of science, against which such accusations are never alleged.
* * * * *
But I must not conceal from you that there are objectors who will
still return to the charge. They will say, "We admit that the
pursuits of the entomologist are important when he directs his views
to the destruction of noxious insects; the discovery of new ones
likely to prove beneficial to man; and to practical experiments
upon their medical and economical properties. But where are the
entomologists that in fact pursue this course? Do they not in reality
wholly disregard the economical department of their science, and
content themselves with making as large a collection of species as
possible; ascertaining the names of such as are already described;
describing new ones; and arranging the whole in their cabinets under
certain families and genera? And can a study with these sole ends in
view deserve a better epithet than trifling? Even if the entomologist
advance a step further, and invent a new system for the distribution
of all known insects, can his laborious undertaking be deemed any
other than busy idleness? What advantage does the world derive from
having names given to ten or twenty thousand insects, of which
numbers are not bigger than a pin's head, and of which probably not a
hundredth part will ever be of any use to mankind?"
Now in answer to this supposed objection, which I have stated as
forcibly as I am able, and which, as it may be, and often is, urged
against every branch of Natural History as at present studied, well
deserves a full consideration, I might in the first place deny that
those who have the highest claim to rank as entomologists do confine
their views to the systematic department of the science to the neglect
of economical observations; and in proof of my assertion, I might refer
abroad to a Linné, a Reaumur, a De Geer, a Huber, and various other
names of the highest reputation; and at home to a Ray, a Lister, a
Derham, a Marsham, a Curtis, a Clark, a Roxburgh, &c. But I do not wish
to conceal that though a large proportion of entomologists direct their
views much further than to the mere nomenclature of their science,
there exists a great number, probably the majority, to whom the
objection will strictly apply. Now I contend, and shall next endeavour
to prove, that entomologists of this description are devoting their
time to a most valuable end; and are conferring upon society a benefit
incalculably greater than that derived from the labours of many of
those who assume the privilege of despising their pursuit.
Even in favour of the mere butterfly-hunter--he who has no higher
aim than that of collecting a _picture_ of _Lepidoptera_, and is
attached to insects solely by their beauty or singularity, it would
not be difficult to say much. Can it be necessary to declaim on the
superiority of a people amongst whom intellectual pleasures, however
trifling, are preferred to mere animal gratifications? Is it a thing
to be lamented that some of the Spitalfields weavers occupy their
leisure hours in searching for the _Adonis_ butterfly (_Polyommatus
Adonis_), and others of the more splendid _Lepidoptera_[72], instead of
spending them in playing at skittles or in an alehouse? Or is there in
truth any thing more to be wished than that the cutlers of Sheffield
were accustomed thus to employ their _Saint Mondays_; and to recreate
themselves after a hard day's work, by breathing the pure air of their
surrounding hills, while in search of this "untaxed and undisputed
game[73];" and that more of the Norwich weavers were fond of devoting
their vacant time to plant-hunting, like Joseph Fox recorded by Sir
James Smith as the first raiser of a Lycopodium from seed[74]?
Still more easy is it to advocate the cause of another description
of entomologists--the general collectors. These, though not
concerning themselves with the system, contribute most essentially
to its advancement. We cannot expect that princes, noblemen, and
others of high rank or large fortune, who collect insects, should
be able or willing to give up the time necessary for studying them
systematically: but their museums being accessible to the learned
entomologist afford him the use of treasures which his own limited
funds or opportunities could never have brought together. As to
others of less consequence that content themselves with the title
of collectors, they also have their use. Having devoted themselves
to this one department, they become more expert at it, than the
philosopher who combines deep researches with the collection of
objects; and thus are many species brought together for the use of
the systematist, that would otherwise remain unknown.
But to proceed to the defence of systematic entomologists.--These
may be divided into two great classes: the first comprising those
who confine themselves to ascertaining the names of the insects they
collect; the second, those who, in addition, publish descriptions of
new species; new arrangements of intricate genera; or extrications of
entangled synonyms; and who, in other respects, actively contribute
to the perfection of the system.
Now with regard to the first class, setting aside what may be urged in
behalf of the study of insects considered as the work of the Creator,
it is easy to show that, even with such restricted views, their pursuit
is as commendable, and as useful both to themselves and the community,
as many of those on which we look with the greatest respect. To say the
least in their favour, they amuse themselves innocently, which is quite
as much as can be urged for persons who recreate their leisure hours
with music, painting, or desultory reading. They furnish themselves
with an unfailing provision of that "grand panacea for the _tædium
vitæ_"--employment--no unimportant acquisition, when even Gray was
forced to exclaim, with reference to the necessity of "always having
something going forward" towards the enjoyment of life, "Happy they
who can create a rose-tree or erect a honey-suckle; that can watch the
brood of a hen, or see a fleet of their own ducklings launch into
the water[75]!" and like the preceding class, they collect valuable
materials for the use of more active labourers, being thus at least
upon a par with the majority of book-collectors and antiquaries.