OTHER INSECT PRODUCTIONS USEFUL TO MAN.
Almost any article could be better spared from the materia medica, than
an insect remedy called _cantharides_, or Spanish flies. This consists
of the bodies of small beetles, in which resides an active blistering
principle of great importance, not only as an external application, but
also sometimes as an internal remedy. The insect chiefly used in Europe
is the _cantharis vesicatoria_, for the most part rare in England, but
seen on some occasions in great numbers, as in the summer of 1837 in
Essex, Suffolk, and the Isle of Wight. Other insects of the same family
are employed in foreign countries.
The true blistering beetle has complete wings and wing cases; its body
is long and narrow, varying in size, but in general about nine lines
long and two or three lines wide. It is of a rich green and golden
colour, very shining and delicately tinctured, with the antennæ black,
except the first joint.
“The cantharis is one of those insects which have been most anciently
and most universally known. Physicians, who were the first natural
philosophers, and the first observers of nature, have made mention of
the cantharides in the remotest times. But they have only considered
them under that relation which was most suitable to their own
profession, and as furnishing to medicine one of its most powerful
agents. The naturalist, who is less anxious about becoming acquainted
with the medicinal virtues of the dead, than with the peculiar habits of
the living cantharides, is yet very far from having acquired in this
respect extensive and satisfactory information. The only species which
has been deemed to be endowed with useful properties, has caused a
forgetfulness of all the others which compose the entire genus; and all
that we know in general respecting these insects, is that in our
European climates they live on plants, devour the leaves of certain
trees, shun the cold, appear at the commencement of spring, and
disappear at the beginning of autumn. * * * It is more than probable
that experiments on insects relatively to their utility in medicine and
the arts, have been too much neglected in general. Their diminutive size
has doubtless caused them to be too much despised. It cannot however be
doubted, that there must be a great number of them whose virtues are at
least equal to those of the cantharides, and many others which are less
acrid and less caustic might in many cases be taken internally, with
less danger and a greater chance of success.”
The early history of this insect is not well known. The female buries
her eggs in the ground; the larvæ have a soft body of a yellowish white
colour; they live in the earth, and feed on various roots. When full
grown they change into the nymph state in the earth, and do not emerge
from it until they have assumed the perfect insect form.
They are very abundant in Spain and in the South of France, especially
in June, when they assemble in swarms. This is the time for gathering
them, and the hour of sunset or sunrise is chosen for the purpose, as
they are then in a somewhat torpid state. They are found upon ash-trees,
honey-suckles, lilacs, rose-trees, poplars, elms, &c., the leaves of
which they devour, and when this food fails they attack corn and grass,
and do much damage. The swarms are preceded by a fœtid odour resembling
that of _mice_. They are gathered in various ways; the most simple is to
spread cloths under the tree upon which a swarm has settled, and then to
shake them down; they are afterwards collected upon a hair sieve, and
held over the vapour of boiling vinegar, which kills them; or the cloth
in which they are collected may be folded loosely up and dipped in
vinegar, which has the same effect. Another method is to boil a quantity
of vinegar under the tree where they are collected, and the ascending
vapour kills them.
The particles emitted by these insects are so very corrosive that
persons are liable to be violently affected who attempt to gather them
with bare hands during the heat of the day. It is also dangerous to be
under a tree where a swarm has gathered. Persons who collect them should
always wear a mask and gloves.
After the insects are killed they must be dried; this is done in the sun
or in a heated room, upon tiles covered with cloth or paper. They are
moved about from time to time with a stick, or with the hands furnished
with gloves. When properly dry they are so light that fifty weigh
scarcely a drachm.
They are packed in boxes or barrels lined with paper and perfectly dry.
If damp gets to them they contract a detestable odour, and are unfit for
use.
A portion of our supply of cantharides is from Astracan and Sicily: but
the greatest quantity is from St. Petersburgh, the Russian insects being
superior to those of Sicily and France.
In using cantharides they are reduced to powder, mixed with some fatty
substance, and applied in the form of a plaster to the surface of the
body: it begins to act immediately, and separates the outer skin from
the dermis with great rapidity.
A singular employment of insects in the composition of _soap_ is made in
some parts of Africa. Geoffrey the younger relates, that being at the
village of Postudal, some leagues from Senegal, in search of insects,
one of the negroes whom he had employed in the same pursuit brought him
a vessel containing an immense quantity of a small species of carabus,
and informed him that this insect entered into the composition of the
soap used in that country; at the same time he exhibited a ball of a
dark-coloured soap, the properties of which are similar to the soap used
in Europe. It appears that the insect abounds in alkali, which makes it
useful for the purpose in question.
The following figure of the soap insect (_Carabus saponarius_), is
copied from M. Olivier’s large work on insects.
[Illustration: [Soap Insect]]
Another useful insect substance is a kind of resin, or more properly
speaking, wax, which by adulteration with a resinous substance is made
heavier for the market. This is found in the province of Coquimbo, South
America, and is the production of a caterpillar, which feeds on a shrub
called _chilca_, a species of origanum. The caterpillars are of a red
colour, and about half an inch in length. They appear in great numbers
in the beginning of the spring on the branches of the chilca, where they
form their cells of a kind of soft wax. In these they become changed
into a small yellowish moth, with black stripes upon the wings. The wax
is at first very white, by degrees becomes yellow, and finally brown;
this change, and the bitter taste which it acquires, is supposed to be
owing to the fogs which are very frequent in the provinces where it is
found. It is collected in autumn by the inhabitants, who boil it in
water, and afterwards make it up into little cakes, in which form it is
brought to market. In order to increase its weight, many are accustomed
to mix it with the resin obtained from another resinous shrub, and in
this state great quantities are sold to ship-masters, who use it for
paying their vessels.
Upon the branches of the wild rosemary is also found a whitish viscous
substance, in globules of the size of a hazel-nut, containing a very
limpid oil, which proceeds from the shrub. These glands serve for the
habitation of a kind of caterpillar, which becomes transformed into a
small fly, with four brown wings, of the genus _Cynips_.
* * * * *
The foregoing details will be sufficient to show that we are indebted in
no small degree to the labours of insects for comfort, convenience, and
health. It becomes us then to receive not unthankfully the benefits they
confer, while we view them as the agents of a higher power, under whose
direction they work with ceaseless activity in their humble sphere, and
produce results, not less astonishing in themselves, than valuable and
beneficial to mankind.
[Illustration: FINIS]
LONDON
R. CLAY, PRINTER, BREAD STREET HILL.
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