animals, equally so is the drinker of tea. Indeed _sugar_ is an
article so universally useful and agreeable, that what concerns the
cane that produces it seems to concern every one. This also affords
a tempting food to insects. The caterpillar of a white moth, called
the borer, for destroying which a reward of fifty guineas is offered
by the Society of Arts, is in this respect a great nuisance, as is an
unknown species of horned beetle[302]. An ant also (_Formica analis_)
makes a lodgement in the interior of the sugar-cane in Guinea, and
destroys it.--But the creature of this class most destructive to the
sugar-cane, is one of the latter genus that does not devour it, and
is therefore improperly called _Formica saccharivora_ by Linné;
but, by making its nest for shelter under the roots, so injures the
plants that they become unhealthy and unproductive. These insects
about seventy years ago appeared in such infinite hosts in the island
of Granada, as to put a stop to the cultivation of this plant; and a
reward of 20,000_l._ was offered to any one who should discover an
effectual mode of destroying them. Their numbers were incredible.
They descended from the hills like torrents, and the plantations, as
well as every path and road for miles, were filled with them. Many
domestic quadrupeds perished in consequence of this plague. Rats,
mice, and reptiles of every kind became an easy prey to them; and
even the birds, which they attacked whenever they alighted on the
ground in search of food, were so harassed as to be at length unable
to resist them. Streams of water opposed only a temporary obstacle
to their progress, the foremost rushing blindly on to certain death,
and fresh armies instantly following, till a bank was formed of
the carcases of those that were drowned sufficient to dam up the
waters, and allow the main body to pass over in safety below. Even
the all-devouring element of fire was tried in vain. When lighted
to arrest their route, they rushed into the blaze in such myriads
of millions as to extinguish it. Those that thus patriotically
devoted themselves to certain death for the common good, were but as
the pioneers or advanced guard of a countless army, which by their
self-sacrifice was enabled to pass unimpeded and unhurt. The intire
crops of standing canes were burnt down, and the earth dug up in
every part of the plantations. But vain was every attempt of man to
effect their destruction, till in 1780 it pleased Providence at
length to annihilate them by the torrents of rain which accompanied a
hurricane most fatal to the other West India Islands. This dreadful
pest was thought to have been imported[303]. Besides these enemies,
the sugar-cane has also its Aphis, which sometimes destroys the
whole crop[304]; and according to Humboldt and Bonpland the larva of
_Elater noctilucus_ feeds in it[305].
Two other vegetable productions of the New World, _cotton_ and
_tobacco_, which are also valuable articles of commerce, receive
great injury from the depredations of insects. M'Kinnen, in his Tour
through the West Indies, states that in 1788 and 1794 two-thirds
of the crop of cotton in Crooked Island, one of the Bahamas, was
destroyed by the _chenille_ (probably a lepidopterous larva); and
the _red bug_, an insect equally noxious, stained it so much in
some places as to render it of little or no value. Browne relates
that in Jamaica a bug destroys whole fields of this plant, and the
caterpillar of that beautiful butterfly _Helicopis Cupido_ also feeds
upon it[306]. That of a hawk-moth, _Sphinx Carolina_, is the great
pest of Tobacco; and it is attacked likewise by the larva of a moth,
_Phalæna Rhexiæ_, Smith[307], and by other insects of the names and
kind of which I am ignorant.
_Roots_ are another important object of agriculture, which, however,
as to many of them, they may seem to be defended by the earth that
covers them, do not escape the attack of insect enemies.--The carrot,
which forms a valuable part of the crop of the sand-land farms in
Suffolk, is often very much injured, as is also the parsnip, by
a small centipede (_Geophilus electricus_), and another polypod
(_Polydesmus complanatus_), which eat into various labyrinths the
upper part of their roots; and they are both sometimes totally
destroyed by the maggot of some dipterous insect, probably one of
the _Muscidæ_. I had an opportunity of noticing this in the month of
July, in the year 1812, in the garden of our valued friend the Rev.
Revett Sheppard of Offton in Suffolk. The plants appeared many of
them in a dying state; and upon drawing them out of the ground to
ascertain the cause, these larvæ were found with their head and half
of their body immersed in the root in an oblique direction, and in
many instances they had eaten off the end of it.
America has made us no present more extensively beneficial, compared
with which the mines of Potosi are worthless, than the _potato_.
This invaluable root, which is now so universally cultivated, is
often, in this country, considerably injured by the two insects
first mentioned as attacking the carrot. The Death's-head-hawk-moth
(_Acherontia Atropos_) in its larva state feeds upon its leaves,
though without much injury. In America it is said to suffer much from
two beetles (_Cantharis cinerea_ and _vittata_), of the same genus
with the blister-beetle[308]; and in the island of Barbadoes some
hemipterous insect, supposed to be a Tettigonia, occasionally attacks
them. In 1734 and 1735 vast swarms of them devoured almost every
vegetable production of that island, particularly the potato, and
thus occasioned such a failure of this excellent esculent, especially
in one parish, that a collection was made throughout the island for
the relief of the poor, whose principal food it forms.
The chief dependence of our farmers for the sustenance of their
cattle in the winter is another most useful root, the _turnip_.
And they have often to lament the distress occasioned by a failure
in this crop, of which these minor animals are the cause. On its
first coming up, as soon as the cotyledon leaves are unfolded, a
whole host of little jumping beetles, composed chiefly of _Haltica
Nemorum_, called by farmers the _fly_[309] and _black jack_, attack
and devour them; so that on account of their ravages the land is
often obliged to be resown, and frequently with no better success.
It has been calculated by an eminent agriculturist, that from this
cause alone the loss sustained in the turnip crops in Devonshire in
1786 was not less than 100,000_l._[310] Almost as much damage is
sometimes occasioned by a little weevil (_Ceutorhynchus contractus_)
which in the same manner pierces a hole in the cuticle. When the
plant is more advanced, and out of danger from these pygmy foes, the
black larva of a saw-fly takes their place, and occasionally does
no little mischief, whole districts being sometimes nearly stripped
by them; so that in 1783 many thousand acres were on this account
ploughed up[311].--The caterpillar of the cabbage-butterfly (_Pontia
Brassicæ_) is also sometimes found upon the turnip in great numbers;
and Sir Joseph Banks informs me that forty or fifty of the insects
before mentioned[312], called by Mr. Walford the wire-worm, have
been discovered in October just below the leaves in a single bulb of
this plant.--The small knob or tubercle often observable on these
roots is inhabited by a _grub_, which, from its resemblance to one
found in similar knobs on the roots of _Sinapis arvensis_, from which
I have bred _Ceutorhynchus contractus_ (_Curculio_ Marsh) and _C.
assimilis_, small weevils nearly related to each other[313]. This,
however, does not seem to affect their growth. Great mischief is
occasionally done to the young plants by the wire-worm. I was shown a
field last summer in which they had destroyed one-fourth of the crop,
and the gentleman who showed them to me calculated that his loss by
them would be 100_l._ One year he sowed a field thrice with turnips,
which were twice wholly, and the third time in great part, cut off
by this insect.--Whether the disease to which turnips are subject,
in some parts of the kingdom, from the form of the excrescences into
which the bulb shoots, called _fingers and toes_, be occasioned by
insects, is not certainly known[314].
* * * * *
We have wandered long enough about the fields to observe the progress
of insect devastation; let us now return home to visit the domains of
Flora and Pomona, that we may see whether their subjects are exposed
to equal maltreatment. If we begin with the _kitchen-garden_, we
shall find that its various productions, ministering so materially to
our daily comfort and enjoyment, almost all suffer more or less from
the attack of the animals we are considering.--Thus, the earliest
of our table dainties, radishes, are devoured by the maggot of a
fly (_Anthomyia Radicum_), and our lettuces by the caterpillars of
several species of moth; one of which is the beautiful tiger-moth
(_Euprepia Caja_), another the pot-herb-moth (_Mamestra oleracea_), a
third anonymous, described by Reaumur as beginning at the root, eating
itself a mansion in the stem, and so destroying the plant before it
cabbages[315]. And when they are come to their perfection and appear
fit for the table, their beauty and delicacy are often marred by the
troublesome earwig, which, insinuating itself into them, defiles them
with its excrements.--What more acceptable vegetable in the spring
than broccoli? Yet how dreadfully is its foliage often ravaged in
the autumn by numerous hordes of the cabbage-butterfly! so that,
in an extensive garden, you will sometimes see nothing left of the
leaves except the veins and stalks.--What more useful, again, than
the cabbage? Besides the same insect, which injures them in a similar
way, in some countries they are infested by the caterpillar of a most
destructive moth (_Mamestra Brassicæ_), to which indeed I have before
alluded[316]; which, not content with the leaves, penetrates into the
very heart of the plant[317].--One of the most delicate and admired of
all table vegetables, concerning which gardeners are most apt to pride
themselves, and bestow much pains to produce in perfection, I mean the
cauliflower, is often attacked by a fly, which ovipositing in that part
of the stalk covered by the earth, the maggots when hatched occasion
the plant to wither and die, or to produce a worthless head[318]. Even
when the head is good and handsome, if not carefully examined previous
to being cooked, it is often rendered disgusting by earwigs that have
crept into it, or the green caterpillar of _Pontia Rapæ_.
Our peas, beans, carrots, parsnips, turnips, and potatos are
attacked in the garden by the same enemies that injure them in the
fields[319]; I shall therefore dismiss them without further notice,
and point out those which infest another of our most esteemed kinds
of pulse, kidney beans. These are principally Aphides, which in
dry seasons are extremely injurious to them. The fluid which they
secrete, falling upon the leaves, causes them to turn black as if
sprinkled with soot; and the nutriment being subtracted from the pods
by their constant suction, they are prevented from coming to their
proper size or perfection. The beans also which they contain are
sometimes devoured by the caterpillar of a small moth[320].--Onions,
which add a relish to the poor man's crusts and cheese, and form
so material an ingredient in the most savory dishes of the rich,
are also the favourite food of the maggot of a fly, that often
does considerable damage to the crop.--From this maggot (for a
supply of onions containing which I have to thank my friend Mr.
Campbell, surgeon, of Hedon near Hull, where it is very injurious,
particularly in light soils,) I have succeeded in breeding the fly,
which proves of that tribe of the Linnean genus _Musca_, now called
_Scatophaga_. Being apparently undescribed, and new to my valued
correspondent Count Hoffmansegg to whom I sent it, I call it _S.
Ceparum_[321].--The diuretic asparagus, towards the close of the
season, is sometimes rendered unpalatable by the numerous eggs of
the asparagus beetle (_Lema Asparagi_), and its larvæ feed upon the
foliage after the heads branch out.--Cucumbers with us enjoy an
immunity from insect assailants; but in America they are deprived
of this privilege, an unascertained species, called there the
cucumber-fly, doing them great injury[322].--And, to name no more,
mushrooms, which are frequently cultivated and much in request, often
swarm with the maggots of various _Diptera_ and _Coleoptera_.
The insects just enumerated are partial in their attacks, confining
themselves to one or two kinds of our pulse or other vegetables. But
there are others that devour more indiscriminately the produce of
our gardens; and of these in certain seasons and countries we have
no greater and more universal enemy than the caterpillar of a moth
called by entomologists _Plusia Gamma_, from its having a character
inscribed in gold on its primary wings, which resembles that Greek
letter. This creature affords a pregnant instance of the power of
Providence to let loose an animal to the work of destruction and
punishment. Though common with us, it is seldom the cause of more
than trivial injury; but in the year 1735 it was so incredibly
multiplied in France as to infest the whole country. On the great
roads, whereever you cast your eyes, you might see vast numbers
traversing them in all directions to pass from field to field; but
their ravages were particularly felt in the kitchen-gardens, where
they devoured every thing, whether pulse or pot-herbs, so that
nothing was left besides the stalks and veins of the leaves. The
credulous multitude thought they were poisonous, report affirming
that in some instances the eating of them had been followed by
fatal effects. In consequence of this alarming idea, herbs were
banished for several weeks from the soups of Paris. Fortunately
these destroyers did not meddle with the corn, or famine would have
followed in their train. Reaumur has proved that a single pair of
these insects might in one season produce 80,000; so that, were the
friendly Ichneumons removed, to which the mercy of Heaven has given
it in charge to keep their numbers within due limits, we should no
longer enjoy the comfort of vegetables with our animal food, and
probably soon become the prey of scorbutic diseases[323].--I must
not overlook that singular animal the mole-cricket, (_Gryllotalpa
vulgaris_,) which is a terrible devastator of the produce of the
kitchen-garden. It burrows under ground, and devouring the roots of
plants thus occasions them to wither, and even gets into hot-beds.
It does so much mischief in Germany, that the author of an old book
of gardening, after giving a figure of it, exclaims, "Happy are the
places where this pest is unknown!"
The _flowers_ and _shrubs_, that form the ornament of our parterres
and pleasure-grounds, seem less exposed to insect depredation than
the produce of the kitchen-garden; yet still there are not a few
that suffer from it. The foliage of one of our greatest favourites,
the _rose_, often loses all its loveliness and lustre from the
excrements of the Aphides that prey upon it. The leaf-cutter bee
also (_Megachile[324] centuncularis_), by cutting pieces out to
form for its young its cells of curious construction, disfigures it
considerably; and the froth frog-hopper (_Cercopis spumaria_) aided
by the saw-fly of the rose (_Hylotoma Rosæ_) contributes to check
the luxuriance of its growth, and to diminish the splendour of its
beauty.--Reaumur has given the history of a fly (_Merodon Narcissi_)
whose larva feeds in safety within the bulbs of the Narcissus, and
destroys them; and also of another, though he neglects to describe
the species, which tarnishes the gay parterre of the florist, whose
delight is to observe the freaks of nature exhibited in the various
many-coloured streaks which diversify the blossom of the tulip,
by devouring its bulbs[325].--Ray notices another mentioned by
Swammerdam, probably _Bibio hortulana_, which he calls the deadliest
enemy of the flowers of the spring. He accuses it of despoiling the
gardens and fields of every blossom, and so extinguishing the hope
of the year[326]. But you must not take up a prejudice against an
innocent creature, even under the warrant of such weighty authority;
for the insect which our great naturalist has arraigned as the author
of such devastation is scarcely guilty, if it be at all a culprit, in
the degree here alleged against it. As it is very numerous early in
the year, it may perhaps discolour the vernal blossoms, but its mouth
is furnished with no instrument to enable it to devour them.
In our _stoves_ and _greenhouses_ the Aphides often reign triumphant;
for, if they be not discovered and destroyed when their numbers
are small, their increase becomes so rapid and their attack so
indiscriminate, that every plant is covered and contaminated by
them, beauty being converted into deformity, and objects before the
most attractive now exciting only nausea and disgust. The Coccus
(_C. Hesperidum_) also, which looks like an inanimate scale upon the
bark, does considerable injury to the two prime ornaments of our
conservatories, the orange and the myrtle; drawing off the sap by its
pectoral rostrum, and thus depriving the plant of a portion of its
nutriment, at the same time that it causes unpleasant sensations in the
beholder from its resemblance to the pustule of some cutaneous disease.
I must next conduct you from the garden into the _orchard_ and
_fruitery_; and here you will find the same enemies still more busy
and successful in their attempts to do us hurt.--The strawberry,
which is the earliest and at the same time most grateful of our
fruits, enjoys also the privilege of being almost exempt from insect
injury. A jumping weevil (_Orchestes Fragariæ_) is said by Fabricius
to inhabit this plant; but as the same species is abundant in this
country upon the beech, the beauty of which it materially injures
by the numberless holes which it pierces in the leaves, and has I
believe never been taken upon the strawberry, it seems probable
that Smidt's specimens might have fallen upon the latter from that
tree[327]. The only insect I have observed feeding upon this fruit is
the ant, and the injury that it does is not material.--The raspberry,
the fruit of which arrives later at maturity, has more than one
species of these animals for its foes. Its foliage sometimes suffers
much from the attack of _Melolontha horticola_[328], a little beetle
related to the cockchafer: when in flower the footstalks of the
blossom are occasionally eaten through by a more minute animal of
the same order, _Byturus tomentosus_, which I once saw prove fatal
to a whole crop; and bees frequently anticipate us, and by sucking
the fruit with their proboscis spoil it for the table.--Gooseberries
and currants, those agreeable and useful fruits, a common object
of cultivation both to poor and rich, have their share of enemies
in this class. The all-attacking Aphides do not pass over them,
and the former especially are sometimes greatly injured by them;
their excrement falling upon the berries renders them clammy and
disgusting, and they soon turn quite black from it. In July 1812 I
saw a currant-bush miserably ravaged by a species of Coccus, very
much resembling the Coccus of the vine. The eggs were of a beautiful
pink, and enveloped in a large mass of cotton-like web, which could
be drawn out to a considerable length. Sir Joseph Banks lately showed
me a branch of the same shrub perforated down to the pith by the
caterpillar of _Æegeria tipuliformis_: the diminished size of the
fruit points out, he observes, where this enemy has been at work.
In Germany, where perhaps this insect is more numerous, it is said
to destroy not seldom the larger bushes of the red currant[329].
The foliage of these fruits often suffers much from the black and
white caterpillar of _Abraxas grossulariata_; (this was the case
last spring at Hull;) but their worst and most destructive enemy,
particularly of the gooseberry, is that of a small saw-fly. This
larva is of a green colour, shagreened as it were with minute black
tubercles, which it loses at its last moult. The fly attaches its
eggs in rows to the underside of the leaves. When first hatched,
the little animals feed in society; but having consumed the leaf on
which they were born, they separate from each other, and the work of
devastation proceeds with such rapidity, that frequently, where many
families are produced on the same bush, nothing of the leaves is left
but the veins, and all the fruit for that year is spoiled[330].
Upon the leaves of the cherry, which usually succeeds the gooseberry,
in common with those of the pear and several other fruit-trees, the
slimy larva of another saw-fly (_Tenthredo Cerasi_) makes its repast,
yet without being the cause of any very material injury. But in
North America a second species nearly related to it, known there by
the name of the _slug-worm_, has become prevalent to such a degree
as to threaten the destruction not only of the cherry, but also of
the pear, quince, and plum. In 1797 they were so numerous that the
smaller trees were covered by them; and a breeze of air passing through
those on which they abounded became charged with a very disagreeable
and sickening odour. Twenty or thirty were to be seen on a single
leaf; and many trees, being quite stripped, were obliged to put forth
fresh foliage, thus anticipating the supply of the succeeding year
and cutting off the prospect of fruit[331].--In some parts of Germany
the cherry-tree has an enemy equally injurious. A splendid beetle of
the weevil tribe (_Rynchites Bacchus_) bores with its rostrum through
the half-grown fruit into the soft stone, and there deposits an egg.
The grub produced from it feeds upon the kernel, and, when about to
become a pupa, gnaws its way through the cherry, and sometimes not one
in a thousand escapes[332]. This insect is fortunately rare with us,
and has usually been found upon the black-thorn. The cherry-fly also
(_Tephritis Cerasi_) provides a habitation for its maggot in the same
fruit, which it invariably spoils[333].
The different varieties of the plum are every year more or less
injured by Aphides; and a Coccus (_C. Persicæ?_) sometimes so abounds
upon them that every twig is thickly beaded with the red semiglobose
bodies of the gravid females, whose progeny in spring exhaust the
trees by pumping out the sap.
The blossoms of our pear-trees, as we learn from Mr. Knight, are often
rendered abortive by the grub of a brown beetle: and a considerable
quantity of its fruit is destroyed by that of a small four-winged fly,
which occasions it to drop off prematurely[334]. This would seem to
be a saw-fly, and is probably the species which Reaumur saw enter the
blossom of a pear before it was quite open, doubtless to deposit its
eggs in the embryo fruit. He often found in young pears, on opening
them, a larva of this genus[335].--A little moth likewise is mentioned
by Mr. Forsyth as very injurious to this tree[336].