them more tempting food, is excellent, and deserves to be pursued
in other instances. It was very successfully employed in 1813 by
J. M. Rodwell, Esq. of Barham Hall near Ipswich, one of the most
skilful and best informed agriculturists in the county of Suffolk,
to preserve some of his wheat-fields from the ravages of a small
gray slug, which threatened to demolish the plant. Having heard that
turnips had been used with success to entice the slugs from wheat, he
caused a sufficient quantity to dress eight acres to be got together;
and then, the tops being divided and the apples sliced, he directed
the pieces to be laid separately, dressing two stetches with them and
omitting two alternately, till the whole field of eight acres was
gone over. On the following morning he employed two women to examine
and free from the slugs, which they did into a measure, the tops and
slices; and when cleared they were laid upon those stetches that
had been omitted the day before. It was observed invariably, that
in the stetches dressed with the turnips no slugs were to be found
upon the wheat or crawling upon the land, though they abounded upon
the turnips; while on the undressed stetches they were to be seen
in great numbers both on the wheat and on the land. The quantity of
slugs thus collected was near a bushel.--Mr. Rodwell is persuaded
that by this plan he saved his wheat from essential injury.
[298] Reaum. v. 11.
[299] Two species are confounded under the appellation of _the grub_,
the larvæ namely of _Tipula oleracea_ and _cornicina_, which last is
very injurious, though not equally with the first. In the rich district
of _Sunk Island_ in Holderness, in the spring of 1813, hundreds of
acres of pasture have been entirely destroyed by them, being rendered
as completely brown as if they had suffered a three months drought, and
destitute of all vegetation except that of a few thistles. A square
foot of the dead turf being dug up, 210 grubs were counted in it!
and, what furnishes a striking proof of the prolific powers of these
insects, the next year it was difficult to find a single one.
[300] Stickney's _Observations on the Grub_.
[301] De Geer, i. 487.
[302] I owe this information to the late Robinson Kittoe, Esq.
[303] Castle in _Philos. Trans._ xxx. 346.
[304] Browne's _Civil and Nat. Hist. of Jamaica_, 430.
[305] _Essai sur la Géographie des Plantes_, 136.
[306] M'Kinnen, 171. Browne _ubi supr._ Merian, _Ins. Sur._ 10.
[307] Smith's Abbott's _Insects of Georgia_, 199.
[308] Illiger, _Mag._ i. 256.
[309] The farmers would do well to change the name of this insect
from _turnip-fly_ to _turnip-flea_, since from its diminutive size
and activity in leaping the latter name is much the most proper. The
term, _the fly_, might with propriety be restricted to the Hop-aphis.
[310] Young's _Annals of Agriculture_, vii. 102.
[311] Marshall in _Philos. Trans._ lxxiii. 1783.
[312] See above, p. 167-168.
[313] Swamm. ii. 81. _col._ b.--Gyllenhal in describing the last-named
species, so common on the flowers of siliquose plants (_Insecta
Suecica_, iii. 142.), asks if his _R. sulcicollis_ (_C. Pleurostigma_,
E. B.), which agrees with it in most respects, except in having toothed
thighs, be not the other sex? This query I can solve in the negative,
having taken the sexes of _R. assimilis_ in coitu, which do not differ,
save that the male has a somewhat shorter rostrum.
[314] Spence's _Observations on the Disease in Turnips called Fingers
and Toes._ Hull 1812. 8vo.
[315] Reaum. ii. 471.
[316] See above, p. 29.
[317] De Geer, ii. 440. In the summer of 1826 when at Brussels, I
observed that delicious vegetable of the _cabbage_ tribe so largely
cultivated there under the name of _Jets de choux_, and which in
England we call _Brussels sprouts_, to be materially injured in the
later stages of its growth by the attacks of the _turnip-flea_, and
other little beetles of the same genus (_Haltica_), which were so
numerous and so universally prevalent, that I scarcely ever examined
a full-grown plant from which a vast number might not have been
collected. Some plants were almost black with them, the species most
abundant being of a dark æneous tinge. They had not merely eroded the
cuticle in various parts, so as to give the leaves a brown blistered
appearance, but had also eaten them into large holes, at the margin
of which I often saw them in the act of gnawing; and the stunted
and unhealthy appearance of the plants sufficiently indicated the
injurious effect of this interruption of the proper office of the
sap. What was particularly remarkable, considering the locomotive
powers of these insects, was that the young turnips, sown in August
after the wheat and rye, close to acres of Brussels sprouts, (which
all round Brussels are planted in the open fields among other crops,)
infested by myriads of these insects, were not more eaten by them
than they usually are in England, and produced good average crops.
It would seem, agreeably to a fact already mentioned, (see Vol. I.
4th Edit. p. 389,) that they prefer the taste of leaves to which they
have been accustomed, to younger plants of the same natural family;
and hence perhaps the previous sowing of a crop of cabbage-plants in
the corner of a field meant for turnips, might allure and keep there
the great bulk of these insects present in the vicinity, until the
turnips were out of danger.
[318] Perhaps this fly is the same which Linné confounded with
_Tachina Larvarum_, which he says he had found in the roots of the
cabbage (_Syst. Nat._ 992. 78.) I say "_confounded_," because it is
not likely that the same species should be parasitic in an insect,
and also inhabit a vegetable.
[319] In lately examining, however, some young garden peas and beans
about four inches high, I observed the margins of the leaves to be
gnawed into deep scollops by a little weevil (_Sitona lineata_), of
which I found from two to eight on each pea and bean, and many in the
act of eating. Not only were the larger leaves of every plant thus
eroded, but in many cases the terminal young shoots and leaves were
apparently irreparably injured. I have often noticed this and another
of the short-snouted Curculios (_S. tibialis_) in great abundance in
pea and bean fields, but was not aware till now that either of them
was injurious to these plants. Probably both are so, but whether the
crop is materially affected by them must be left to further inquiry.
[320] Reaum. ii. 479.
[321] Description of _S. Ceparum_.--Cinereous, clothed with distant
black hairs, proceeding, particularly on the thorax, from a black
point. Legs nigrescent. Back of the abdomen of the male with an
interrupted black vitta down the middle. Wings immaculate. Poisers
and alulæ pale yellow. Length 3-1/2 lines.
[322] Barton in _Philos. Magaz._ ix. 62.
[323] Reaum. ii. 337.
[324] _Apis._ **. c. 2. α. K.
[325] Reaum. iv. 499.
[326] Rai. _Hist. Ins._ Prolegom. xi.
[327] This kind of misnomer frequently occurs in entomological
authors.--Thus, for instance, the _Curculio (Rynchites) Alliariæ_ of
Linné feeds upon the hawthorn, and _Curculio (Cryptorhynchus) Lapathi_
upon the willow (Curtis in _Linn. Trans._ i. 86.); but as _Alliaria_
is common in hawthorn hedges, and docks often grow under willows, the
mistake in question easily happened: when, however, such mistakes are
discovered, the _Trivial Name_ ought certainly to be altered.
[328] I consider this insect as the type of a new subgenus
(_Phyllopertha_, K. MS.), which connects those tribes of
_Melolontha_, F. that have a mesosternal prominence with those that
have not. Of this subgenus I possess six species. It is clearly
distinct from _Anisoplia_, under which DeJean arranges it.
[329] _Wiener Verzeich._ 8vo. 29.
[330] Fabricius seems to have regarded the saw-fly that feeds upon
the _sallow_ (_Nematus Capreæ_), not only as synonymous with that
which feeds upon the _osier_, but also with our little assailant
of the _gooseberry_ and _currant_. Yet it is very evident from
Reaumur's account, whose accuracy may be depended upon, that they are
all distinct species. Fabricius's description of the _fly_ agrees
with the insect of the gooseberry, but that which he has given of
the _larva_ belongs to the animal inhabiting the sallow. Probably,
confounding the two species, he described the imago from the insect
of the former, and the larva (if he did not copy from Reaumur or
Linné) from that of the latter. Linné was correct in regarding
Reaumur's three insects as distinct species, though he appears to be
mistaken in referring to him under _N. flavus_, as the saw-fly of the
currant and gooseberry is not wholly yellow.
[331] Peck's _Nat. Hist. of the Slug-worm_, 9.
[332] _Trost Kleiner Beytrag_. 38.
[333] Reaum. ii. 477.
[334] _On the Apple and Pear_, 158. The beetle Mr. Knight alludes to
is probably the _Polydrosus oblongus_, which answers his description,
and is common on pear-trees.--In Holland, it is stated in a little
tract on this subject (_Verhandeling ten bewijze &c. door_ F. H. van
Berck. 8vo. Haarlem 1807), that the great destroyer of the blossoms
of their apple- and pear-trees is the larva of another weevil,
_Anthonomus Pomorum_, which from the name and Gyllenhal's addition
to the habitat given by Linné--"quas destruit"--should seem to be
injurious in Sweden also.
[335] Reaum. _ubi supr._ 475.
[336] _On Fruit Trees_, 271.
[337] _On the Apple and Pear_, 45.
[338] Reaum. ii. 499.
[339] Mr. Scales.
[340] See Observations on this Insect in the 2nd volume of the
_Horticultural Society's Transactions_, p. 25. By W. Spence.
[341] Reaum. iv. 69. _t._ 5. _f._ 6, 7.
[342] A solution of quick-lime is recommended in the _Gardener's
Magazine for January_ 1828, a periodical work which every friend of
Horticulture ought to possess.
[343] This Aphis is evidently the insect described in Illiger's
_Magazin_, i. 450. under the name of _A. lanigera_, as having done
great injury to the apple-trees in the neighbourhood of Bremen in 1801.
That it is an Aphis and no Coccus is clear from its _oral_ rostrum and
the wings of the male, of which Sir Joseph Banks possesses an admirable
drawing by Mr. Bauer. On this Aphis see Forsyth, 265; _Monthly Mag._
xxxii. 320; and also for August 1811; and Sir Joseph Banks in the
_Horticultural Society's Transactions_, ii. 162. Those Aphides that
transpire a cottony excretion are now considered as belonging to a
distinct genus, under the name of _Myzoxyla_.
[344] M. de la Hire in Reaum. ii. 478.
[345] Dr. Smith Barton's Letter in _Philos. Magaz._ xxii. 210.
William Davy, Esq. American Consul of the Port of Hull, long resident
in the United States, informed me that though he had abundance of
peaches at his country-house, German Town near Philadelphia, he could
never succeed with the nectarine, the fruit constantly falling off
perforated by the grub of some insect.
[346] _Descr. of the I. of St. Helena_, 147.
[347] A mode of destroying this hurtful insect is given in a Number
of that useful and interesting work, the _Gardener's Magazine_, just
quoted.
[348] Reaum. ii. 505.
[349] Ibid. ii. 507. and Hasselquist's _Travels in the Levant_, 428.
[350] That is "High and Low," Judges ix. 13.
[351] Sturm _Deutschlands Fauna_, i. 5.
[352] Latreille, _Hist. Nat._ xi. 66. 331.
[353] Host in Jacquin. _Collect._ iii. 297.
[354] Pallas's _Travels in S. Russia_, ii. 241.
[355] Jacquin. _Collect._ ii. 97.
[356] Deut. xxviii. 39.
[357] _Travels_, ii. 6.
[358] Collinson in _Philos. Trans._ liv. x. 65.
[359] Rösel, I. ii. 15.
[360] Reaum. ii. 122.
[361] Mouffet, 160.
[362] _Philos. Trans._ xix. 741.
[363] Reaum. i. 387. These larvæ were so extremely numerous in 1826
on the limes of the _Allée Verte_ at Brussels, that many of the trees
of that noble avenue, though of great age, were nearly deprived of
their leaves, and afforded little of the shade which the unusual
heat of the summer so urgently required. The moths which in autumn
proceeded from them, when in motion towards night, swarmed like
bees, and subsequently on the trunk of every tree might be seen
scores of females depositing their down-covered patch of eggs. In the
_Park_ they were also very abundant; and it may be safely asserted
that if one half of the eggs deposited were to be hatched, in 1827
scarcely a leaf would remain in either of these favourite places
of public resort. Happily, however, this calamity seems likely to
be prevented. Of the vast number of patches of eggs which I saw on
almost every tree in the park about the end of September, I could
two months afterwards to my no small surprise, discover scarcely
one, though the singularity of the fact made me examine closely.
For their disappearance I have no doubt the inhabitants of Brussels
are indebted to the tit-mouse (_Parus_), the tree-creeper (_Certhia
familiaris_), and other small birds known to derive part of their
food from the eggs of insects, and which abound in the park, where
they may be often seen running up and down the trunks of the trees,
at once providing their own food and rendering a service to man,
which all his powers would be inadequate completely to effect.
Reaumur (ii. 106) in certain seasons found these patches of eggs so
numerous, that in the _Bois de Boulogne_ there was scarcely an oak,
the under side of the branches of which were not covered by them for
an extent of seven or eight feet. He informs us that the eggs are not
hatched till the following spring.
[364] _Wiener Verzeich._ 8vo. 75.
[365] Curtis _Brit. Ent._ _t_. 117.
[366] De Geer, ii. 452.
[367] Kalm's _Travels_, ii. 7.
[368] The same intelligent gentleman related to me, that a person
having taken some land at Bahia in the Brazils, he was compelled by
these ants, which were so numerous as to render every effort to destroy
them ineffectual, to relinquish the occupation of it. Their nests were
excavated to the astonishing depth of fourteen feet. Merian _Insect.
Sur._ 18. Smeathman on _Termites, Phil. Trans._ lxxi. 39. note 35.
[369] Stedman, ii. 142.
[370] _Hist. Nat._ l. xi. c. 12.
[371] Curtis _Brit. Ent._ t. 60.
[372] Lewin in _Linn. Trans._ iii. 1.--Curtis in do. i. 86.
[373] Curtis _Brit. Ent._ _t._ 104.
[374] MacLeay in _Edinburgh Philos. Journ._ n. xxi. 123. Curtis
_Brit. Ent._ _t._ 43.
[375] Wilhelm's _Recreations from Nat. Hist._ quoted by Latreille
_Hist. Nat._ xi. 194.
[376] Reaum. ii. 502.
LETTER VII.
_INJURIES CAUSED BY INSECTS._
INDIRECT INJURIES CONTINUED.
To look at a _locust_ in a cabinet of insects, you would not, at first
sight, deem it capable of being the source of so much evil to mankind
as stands on record against it. "This is but a small creature," you
would say, "and the mischief which it causes cannot be far beyond the
proportion of its bulk. The locusts so celebrated in history must
surely be of the Indian kind mentioned by Pliny, which were three
feet in length, with legs so strong that the women used them as saws.
I see indeed some resemblance to the horse's head, but where are the
eyes of the elephant, the neck of the bull, the horns of the stag, the
chest of the lion, the belly of the scorpion, the wings of the eagle,
the thighs of the camel, the legs of the ostrich, and the tail of the
serpent, all of which the Arabians mention as attributes of this widely
dreaded insect destroyer[377]; but of which in the insect before me I
discern little or no likeness?" Yet, although this animal be not very
tremendous for its size, nor very terrific in its appearance, it is
the very same whose ravages have been the theme of naturalists and
historians in all ages, and upon a close examination you will find it
to be peculiarly fitted and furnished for the execution of its office.
It is armed with two pair of very strong jaws, the upper terminating
in short and the lower in long teeth, by which it can both lacerate
and grind its food--its stomach is of extraordinary capacity and
powers--its hind legs enable it to leap to a considerable distance,
and its ample vans are calculated to catch the wind as sails, and so
to carry it sometimes over the sea; and although a single individual
can effect but little evil, yet when the entire surface of a country
is covered by them, and every one makes bare the spot on which it
stands, the mischief produced may be as infinite as their numbers. So
well do the Arabians know their power, that they make a locust say to
Mahomet--"We are the army of the Great God; we produce ninety-nine
eggs; if the hundred were completed, we should consume the whole earth
and all that is in it[378]."
Since it is possible you may not have paid particular attention to
the accounts given by various authors both ancient and modern, of the
almost incredible injury done to the human race by these creatures,
I shall now lay before you some of the most striking particulars of
their devastations that I have been able to collect.
The earliest plague of this kind which has been recorded, appears
also to have been the most direful in its immediate effects that
ever was inflicted upon any nation. I am speaking, as you may well
suppose, of the locusts with which the Egyptian tyrant and his people
were visited for their oppression of the Israelites. Only conceive to
yourself a country so covered by them that no one can see the face of
the ground--a whole land darkened, and all its produce, whether herb
or tree, so devoured that not the least vestige of green is left in
either[379].--But it is not necessary for me to enlarge further upon
a history the circumstances of which are so well known to you.
To this species of devastation Africa in general seems always to
have been peculiarly subject. This may be gathered from the law
in Cyrenaica mentioned by Pliny, by which the inhabitants were
enjoined to destroy the locusts in three different states, three
times in the year--first their eggs, then their young, and lastly
the perfect insect[380]. And not without reason was such a law
enacted; for Orosius tells us that in the year of the world 3800,
Africa was infested by such infinite myriads of these animals, that
having devoured every green thing, after flying off to sea they were
drowned, and being cast upon the shore they emitted a stench greater
than could have been produced by the carcases of 100,000 men[381].
St. Augustine also mentions a plague to have arisen in that country
from the same cause, which destroyed no less than 800,000 persons
(_octingenta hominum millia_) in the kingdom of Masanissa alone, and
many more in the territories bordering upon the sea[382].
From Africa this plague was occasionally imported into Italy and
Spain; and a historian quoted in Mouffet relates that in the year 591
an infinite army of locusts of a size unusually large, grievously
ravaged part of Italy; and being at last cast into the sea, from
their stench arose a pestilence which carried off near a million of
men and beasts. In the Venetian territory, also, in 1478 more than
30,000 persons are said to have perished in a famine occasioned by
these terrific scourges. Many other instances of their devastations
in Europe, in France, Spain, Italy, Germany, &c.[383], are recorded
by the same author. In 1650 a cloud of them was seen to enter Russia
in three different places, which from thence passed over into Poland
and Lithuania, where the air was darkened by their numbers. In some
places they were seen lying dead heaped one upon another to the
depth of four feet; in others they covered the surface like a black
cloth, the trees bent with their weight, and the damage they did
exceeded all computation[384]. At a later period in Languedoc when
the sun became hot they took wing and fell upon the corn, devouring
both leaf and ear, and that with such expedition that in three hours
they would consume a whole field. After having eaten up the corn
they attacked the vines, the pulse, the willows, and lastly the hemp
notwithstanding its bitterness[385]. Sir H. Davy informs us[386] that
the French government in 1813 issued a decree with a view to occasion
the destruction of grasshoppers.
Even this happy island, so remarkably distinguished by its exemption
from most of those scourges to which other nations are exposed, was
once alarmed by the appearance of locusts. In 1748 they were observed
here in considerable numbers, but providentially they soon perished
without propagating. These were evidently stragglers from the vast
swarms which in the preceding year did such infinite damage in
Wallachia, Moldavia, Transylvania, Hungary, and Poland. One of these
swarms, which entered Transylvania in August, was several hundred
fathoms in width, (at Vienna the breadth of one of them was three
miles,) and extended to so great a length as to be four hours in
passing over the Red Tower; and such was its density that it totally
intercepted the solar light, so that when they flew low one person
could not see another at the distance of twenty paces[387]. A similar
account has been given me by a friend of mine[388] long resident in
India. He relates that when at Poonah he was witness to an immense
army of locusts which ravaged the Mahratta country, and was supposed
to come from Arabia (this, if correct, is a strong proof of their
power to pass the sea under favourable circumstances). The column
they composed, my friend was informed, extended five hundred miles;
and so compact was it, when on the wing, that like an eclipse it
completely hid the sun, so that no shadow was cast by any object, and
some lofty tombs distant from his residence not more than two hundred
yards were rendered quite invisible. This was not the _Locusta
migratoria_, but a red species; which circumstance much increased the
horror of the scene; for, clustering upon the trees after they had
stripped them of their foliage, they imparted to them a sanguine hue.
The peach was the last tree that they touched.
Dr. Clarke, to give some idea of the infinite numbers of these
animals, compares them to a flight of snow when the flakes are
carried obliquely by the wind. They covered his carriage and horses,
and the Tartars assert that people are sometimes suffocated by them.
The whole face of nature might have been described as covered by
a living veil. They consisted of two species, _L. tatarica_ and
_migratoria_; the first is almost twice the size of the second,
and, because it precedes it, is called by the Tartars the herald or
messenger[389].--The account of another traveller, Mr. Barrow, of
their ravages in the southern parts of Africa (in 1784 and 1797) is
still more striking: an area of nearly two thousand square miles
might be said literally to be covered by them. When driven into the
sea by a N. W. wind, they formed upon the shore for fifty miles a
bank three or four feet high, and when the wind was S. E. the stench
was so powerful as to be smelt at the distance of 150 miles[390].