entrapped them, is to bring them _safe_ home. The Entomologists on
the Continent, I believe, generally transfix their prey, of whatever
Order, with a pin, as soon as they are caught: but as _hard_ ones,
such as _Coleoptera_, _Hemiptera_, &c., may be destroyed without
injury by immersion either in spirits of wine or boiling water; and
as large beetles, if transfixed (not to mention the unnecessary
cruelty of so serving them), are apt to whirl round upon the pin in
spite of any precaution, and injure themselves, and destroy other
insects that are in their way, it seems best to kill them by other
more effectual methods. With regard to those that would be injured
by immersion in any fluid, as the _Lepidoptera_, _Hymenoptera_,
_Diptera_, &c., they must be secured as soon as taken; and after
having disabled them as much as you can without injuring them, by
pressing the trunk below the wings with the finger and thumb, they
should be transfixed and put into a pocket-box lined with cork. Some
use an oblong deep chip one, with paper pasted over it, and lined at
top and bottom, the top being convenient for setting small moths. But
this you will find not easy to open when you have an insect in one
hand; and it is too deep for the pocket. I generally use a mahogany
one, about 7-1/2 inches by 4-1/2 and 1-1/4 deep in the clear, corked
only at the bottom, and opening by pressing a spring, which can be
done with one hand. This will contain as many of the above insects
as you will usually take in a day's excursion. When travelling, you
should provide yourself with larger store-boxes, to receive at night
the fruit of the day's hunt. These may be 18 inches square and 2-1/2
deep, corked at top and bottom; which should be of equal depth,
and fit very closely, to keep out _Acari_, &c. Entomologists have
recourse to various ways of bringing home insects for immersion. For
the larger ones, you must be provided with a number of small boxes,
the lids of which are not liable to come off in the pocket. If it can
be done, it is best to have only a single insect in a box. If you
have several, those that are predaceous in their habits will probably
devour the rest: and besides, if you open a box to put in other
insects, generally one or two of those before imprisoned in it will
make their escape. It is best to put the boxes containing an insect
in one pocket, and the empty ones in another. If your boxes are
numbered, in a small memorandum-book, which you should carry for the
purpose, you may make any remarks as to the food, station, and habits
of any insect you may take, inserting against them the number of the
box or phial that contains it, and it will be ready for future use.
For the smaller beetles, &c. a number of phials, with their rims
ground down and the mouths well fitted with corks, must be provided;
but for those you do not wish to keep separate, a wide-mouthed phial
filled with spirits of wine, which soon kills them, is the best
receptacle. I have found, when at a loss, a piece of elder, with
the pith taken out to a sufficient depth at each end and each mouth
stopped with a wooden plug, a useful insect box. As numerous insects
inhabit the various species of _Boleti_, if you go where these are to
be found, unless you are a very agile person and expert at climbing,
a boy with a short light ladder will be no useless accompaniment.
Something may be said in this place upon the _dress_ with which the
Entomologist should provide himself. I shall not recommend to you,
in imitation of the insect-hunters in the vignette to Reaumur's
second volume, to put on a bag-wig and a velvet court-dress; but the
plain fustian jacket with side and other pockets used by English
sportsmen will very well suit your purpose; only let the pockets be
sufficiently ample: have also an inside one fixed on the left-hand
side to receive your forceps. You may also have a bag like a
shooter's, or an angler's basket, which may contain your nets till
you want to use them. With all your implements about you, you will
perhaps at first be stared and grinned at by the vulgar; but they
will soon become reconciled to you, and regard you no more than your
brethren of the angle and of the gun. Things that are unusual are
too often esteemed ridiculous; and the philosopher whose object is
to collect and study the wonderful works of his CREATOR, is often
regarded by the ignorant plebeian as little short of a madman.
Such is the apparatus to be provided by the entomological Nimrod:
it is not often, however, that it will be necessary, except in
distant excursions, to encumber and disfigure yourself with the
whole. Even in this pursuit more may be effected by a judicious
division of labour, than by grasping at every thing at once; and your
acquisitions will in the end be more numerous, and your acquaintance
with them more intimate, if at one time you devote yourself to the
woods and hedges, another to the plains and meadows, a third to any
heaths in your vicinity, and a fourth to the collection of aquatic
insects whether from stagnant or running waters:--having thus chosen
the scene of action, you may equip yourself accordingly. You will
of course, though in pursuit of a particular description of game,
not neglect to seize any other insects that fall in your way; but
for this purpose it is unnecessary to be always provided with a
certain instrument. Dr. Franklin used to say that a man would never
make a Natural Philosopher, who, in performing his experiments,
could not saw with a gimblet or bore with a saw; and so we may say,
he will never make an expert collector of insects, who on occasion
cannot fish with his hand or forceps, use his hat or an old letter
to beat his game into, or, in the absence of boxes or bottles,
contrive to secure his captures in small pieces of paper twisted up.
Sparrman, when at the Cape, was wont,--to the no small amazement of
the wondering natives, who took him for a conjurer,--to stick his
impaled insects round the outside of his hat[1563]: and though I
should not recommend such an exhibition in a civilized region, it
has often struck me that the cavity of a modern hat, if lined with
cork, might be made a very useful receptacle for these animals in a
long excursion. Indeed, an active Entomologist is never at a loss
for an apparatus, but often makes his most valuable captures when
unprovided with other instruments than his hands and eyes. A careful
survey of the trunk and branches of trees and shrubs, particularly of
the underside of their leaves, seldom fails to detect many a lurking
moth or beetle, which may be transfixed or otherwise captured with
little trouble by an expert hand. In this way an ingenious collector,
who scarcely knew what a net of any kind was, told me he had made his
whole collection, which was rather extensive. It is, in fact, only
by thus detecting them when reposing, and adroitly shutting them up
along with the leaf on which they sit, in a box, that minute moths
(whose beauty and freshness the slightest handling destroys) can
ordinarily be taken without being injured. The boxes containing them
should afterwards be exposed to the action of heat, a low degree of
which will destroy them.
* * * * *
Enough has been said upon the best modes of _catching_ insects:--I
shall next attempt to give you some further instructions as to the
most effectual one of _destroying_ them when caught, and to point
out how you are to proceed with them after they are dead. As I
sufficiently rebutted the charge of cruelty in a former letter[1564],
it will not be necessary to enter here into that subject.
I have before recommended to you the use of _spirits of wine_, and
shall here repeat my recommendation; for after several years trial,
I am of Böhm's opinion, who had tried it nine years[1565], that it
is superior to any other method; particularly, because it not only
effectually kills the insects, and they may be put together into it
while you are collecting, if you have no reason for keeping them
separate, of all sorts and sizes, in a wide-mouthed phial, without
danger of their devouring each other: but when you come home wearied
with a long day's hunt, you may let your insects remain in it without
injury till the next morning. In collecting beetles abroad, when
there is a want of store-boxes the readiest way is to put them into
a wide-mouthed bottle or jar filled with any spirit, and send them
home in it: some few may lose their colours, or become greasy; but in
general they will receive little injury. This method saves room, and
avoids the risk of breakage. The derangement which some hairy species
sustain from this method may be readily repaired by brushing them
with a dry camel's-hair pencil.
When you wish to take the insects you have immersed in spirits
out of the phial, you must strain its contents through a piece of
muslin, return the spirit into it for future use, and spread the
insects _separately_ upon blotting-paper, to absorb the moisture
remaining about them. With regard to such as you have in boxes or
phials without spirit, these must be immersed in a basin of _boiling_
water. First empty into it the contents of your boxes, and next,
those of your phials; giving each, before you take out the cork,
a smart rap, that the insects adhering to the latter may drop to
the bottom: or you may immerse the phial itself, with the cork in,
which soon destroys them, and is the safest plan. This done, with a
camel's-hair pencil or feather take them out of the water, lay them
upon blotting-paper to dry, and put them by for a few hours till you
have leisure to impale and set them.
Those insects that are caught by the _forceps_ would for the most
part escape you, were you to attempt to get them out before you had
transfixed them. You must therefore do this while the leaves of the
instrument are closed; and then opening them, and taking the pin by
the point, the head will readily pass through the catgut; and thus
you may safely take, and more effectually kill your specimen by
pressing it as before directed. With respect to _Lepidoptera_, it
is necessary to disable them while yet in the fly-net, immediately
after their capture. To effect this, while one hand holds both the
rods of the closed net, with the other stretch the gauze so as to
confine your insect within a narrow space; bring its wings into an
erect position, and prevent its fluttering: which being done, with
your finger and thumb give its breast a strong pinch below the wings;
and then unfolding your net, and taking it up by one of its antennæ,
place it between the finger and thumb of your left hand, stick a pin
through it, and deposit it in your pocket-box.
But though nipping the breast will kill many small _Lepidoptera_,
the larger ones will live long after it; as will likewise many
_Neuroptera_, _Hymenoptera_, and _Diptera_: and besides this, in some
_Bombycidæ_ the thorax presents a very conspicuous and interesting
character, which renders it desirable, in order to avoid the damage
or derangement occasioned by pressure, to transfix them without it.
To dispatch these effectually, you will find the following apparatus
very convenient. Fix in a small tin saucepan[1566] filled with boiling
water, a tin tube consisting of two pieces[1567] that fit into each
other; cover the mouth of the lower one[1568] with a piece of gauze or
canvass, and place your insects upon it; then fix the upper one[1569]
over it, and cover also the mouth of this with gauze, &c.; and the
steam from the boiling water will effectually kill your insects without
injuring their plumage. There is another more simple mode of doing
this, the apparatus for which may be met with every where. Fix a piece
or two of elder, willow, or any soft wood, with the bark on, across the
bottom of a mug, and on this stick your impaled insects; invert the
mug in a deep basin, into which pour boiling water till it is covered,
holding it down with a knife, &c., that the expansion of the included
air may not overturn it. In two minutes, or less, all the insects
will be found quite dead, and not at all wetted. If the sticks do not
exactly fit, they may be wedged in with a piece of cork. Professor
Peck, who used to put minute insects into the hollow of a quill stopped
with a piece of wood made to fit, killed them instantaneously by
holding it over the flame of a candle.
Having killed your insects, your next object should be to prepare
them for your cabinet. First, place by you a pincushion well stored
with lace-pins of various magnitudes and lengths: for most insects
those nearly an inch in length, for large ones, those that are
thicker and longer, but for _Lepidoptera_, a stouter kind, as _short
whites_, are best. Next, take the _Coleoptera_ and _Hemiptera_
that, as before directed, you have laid by on blotting-paper after
immersion, and begin your operations, selecting the largest first.
The pin should be stuck through the middle of the right-hand
elytrum[1570], and about _one third_ of its whole length should
emerge above the insect. Some _foreign_ collectors, probably having
in view its more convenient examination with a microscope under
the glass of a drawer, bring it nearer the head of the pin: while
the _English_ ones, on the contrary, studying the most ornamental
position of their specimens, leave only enough of the point free to
fix them safely in their drawers[1571]. Both these methods are open
to objection. When the insect is too near the head of the pin, it is
difficult to fix it in your cabinet without bending the wire; and
there is danger, without great care, of injuring the specimen when
you put it in or take it out. Again: When the legs of your insect
rest on the surface they collect the dust and dirt, are very liable
to be broken, and the length of the pin above it is inconvenient when
you have occasion to examine any one under a lens. _Lepidoptera_,
however, which are never thus examined, may always be transfixed in
this way, which sets them off to the greatest advantage.
Some insects, especially of the beetle tribe, are so extremely minute
that it is next to an impossibility to get a pin through them without
injuring, and often destroying them. By using fine needles, or very
slender pins manufactured on purpose, this difficulty might perhaps
be surmounted; but the needles will be subject to rust, and the pins,
I know by experience, cannot be fixed in cork without difficulty. For
such minute insects, therefore, by far the best mode is to _gum_ them
on small pieces of card, which may be stuck upon a pin. Talc, which
admits the underside of an insect to be seen through it, has been
used for this purpose; and where you have only a single specimen, a
thin small lamina of it would answer well; but ordinarily I should
recommend the former mode. Your pieces of card, which must be small,
may be either oblong and cut at the corners for neatness, with a
couple of specimens gummed upon each, one on its belly and the other
on its back; or you may cut little narrow card wedges, about four
lines long and terminating in a point, upon which you may so gum your
insects as to show the principal part of the under side, as well as
the upper side of its body. Common gum-water made rather thin, with a
very little glue mixed with it, will answer your purpose very well:
it should be thinly spread on the card with a camel's-hair pencil,
and then the insect placed upon it. With the same implement, if it
has not been killed too long, before the gum is dry you may expand
its antennæ, palpi, legs, and wings, &c. If you want to remove a
specimen gummed on a card for any purpose, it is easily effected by
plunging it into hot water.
Other insects may be transfixed through the thorax or upper side of
the trunk; as also those _Coleoptera_, _Orthoptera_, and _Hemiptera_,
whose wings you are desirous of expanding; only you should be careful
that your pin passes through them _behind_ the _prothorax_.
Having impaled your insects, the next thing to be done is to _set_
them. The best time for doing this is not till they have begun to
stiffen, but before they are become quite stiff. If attempted soon
after they are killed, the parts, unless you keep them in the intended
position by means of pins or braces, will not retain it; and if after
they are become too stiff, they are liable to be broken. Not only
should the antennæ and palpi be extended so as to be readily seen; but
the legs, and often the wings, ought to be placed in their natural
position; all of which tends much to the beauty of your specimens, and
adapts them for more ready examination. But as this operation requires
time, and beauty and regularity may be purchased too dear if at the
price of hours called for by science, you may be left to your own
discretion in this business, only you should always with a pin expand
the antennæ and palpi if possible. You might, however, both save your
time and have your insects neatly set, if you would take the trouble
to instruct some acute and handy youth in your neighbourhood in the
_modus operandi_, and devolve this department upon him: and as none are
quicker and more expert in capturing insects than boys, he might also
assist you in your hunting expeditions.
I do not mean, however, to leave you at liberty with regard to the
setting of _Lepidopterous_ insects, which not only have a much worse
appearance than those of other Orders if their wings be not regularly
and uniformly expanded, but require it for the proper display of
their characters. The necessary apparatus consists of a piece of cork
about nine inches long, four broad, and half an inch thick, which
should be made perfectly smooth, with a piece of white paper pasted
over it; and of several narrow slips of card or braces, tapering
gradually to a point, of different lengths, from half an inch to two
inches or more, with a pin fixed in each at the broadest end. Thus
provided, you may proceed to action. But you must first decide whether,
like the continental Entomologists, you will set your _Lepidoptera_
horizontally; or, like the British, with their wings declining
obliquely from the body. If you prefer the former method, the body must
be let into a groove, and the wings expanded as flatly as possible,
the anterior margin of the primary pair being brought forward so as
to project beyond the head. But as this usually gives the insect an
unnatural and formal appearance, I apprehend a man of your taste will
prefer the mode adopted by your compatriots, the collectors of Britain,
who in setting make the wings form an angle, varying according to the
size and characters of the insect, with the body, and do not bring
the anterior wings so forward. The wings of butterflies however, in
order to appear at all natural, should be set more horizontally. Which
fashion soever you prefer, the mode of operating is nearly the same;
only that the English plan, except in the case of some large-bodied
moths or hawk-moths, requires no groove in the setting-board. After
you have stuck the insect upon the cork so as to bring its body close
to its surface, stretch the anterior wing with a needle fixed in a
handle, or a camel's-hair pencil, applied to the joint at the base,
sufficiently forward, and then confine it by means of one of your card
braces:--next, do the same by the opposite wing. Afterwards expand the
posterior wings, which must not be separated from the anterior so as
to leave any interval between them, and fix them with braces. When
you are become expert, you will find, if the fly is not large, that
a single brace will be sufficient for each pair of wings[1572]: but
sometimes, if the card be not sufficiently stiff, you may confine it
by a pin near the point. You must be careful in expanding the wings
that each is brought equally forward. Lastly, give the antennæ their
proper position, and if necessary confine them with braces; and leave
your specimen in an airy situation to dry and stiffen. In a few days
the braces may be removed, and the specimen transferred to the cabinet.
When you put them away to become stiff, you must be careful to place
them and your other insects at _night_ where earwigs cannot come at
them; for in sultry weather these animals will often then attack and
spoil them.
It is obvious that this process can only be performed while the
joints and ligaments of the insect are still flexible; so that
small species, in warm weather, will often be immoveably rigid
before you can have an opportunity of setting them. On this account
collectors usually set minute moths as soon as taken, which can be
readily done on the lid of a cork-lined box. But fortunately both
these, and specimens which have been dried for years, may be relaxed
and rendered pliable by a very simple process. Fill a basin more
than half full of sand, and saturate it with water; pour off the
superfluous water, and cover the sand with blotting-paper: into this
stick the insects you wish to relax, and covering the basin closely,
leave them there for two or three days, according to their size; and
the evaporation will render them sufficiently flexible for expansion
or any other purpose. Beetles may be relaxed by plunging them for a
short time in warm water or spirits of wine[1573].
Many moths of the tribe of _Tinea_ L. are so extremely minute,
that it is almost impossible to set them without defacing their
characters: indeed, the trunk of some is so small as not to admit
being pierced by a pin. These, therefore, it is adviseable merely
to gum upon card, expanding their wings (which the gum will easily
retain in their proper situation) with a camel's-hair pencil. If
you have two specimens, you may fix one in the natural position
when at rest,--a method I should recommend with respect to other
_Lepidoptera_, and indeed insects in general. Pezold advises that,
by way of contrast, _white_ card should be used for _dark_-coloured
species of these little moths, and _black_ for such as are _pale_.
As the wings of different _Coleopterous_ groups, as well as those of
_Hymenoptera_, _Diptera_, &c., vary in their neuration[1574], you
should, whenever you can, set open the elytra and expand the wings of
one specimen at least in each group, which will be very important to
you in making out the characters of your genera.
When sufficiently dried, your insects should be transferred from
the setting-boards, either to their place in your cabinet or to the
store-box before described, till you have leisure to investigate them.
However tedious some of the foregoing manipulations may seem, they
are in fact much less so than those required in several other
branches of Natural History, where, in addition to the labour of
catching, the nice and difficult task of clearing the skeleton of
its muscular covering, and its internal cavity of its contents,
and then of stuffing it and replacing its perished eyes by glass
ones of the proper colour, is a necessary process with every
individual. Happily the Entomologist, from the smallness of his game
and the nature of their integument, is usually spared this labour.
There are some few insects, however, in which a process in some
degree analogous is requisite, if the beauty of the specimens be a
consideration. Thus the abdomen of _dragon-flies_ is very apt to lose
its colour, and that of the _Meloës_ to shrink up, if left in their
natural state: these therefore should be eviscerated; which may be
done by slitting the abdomen longitudinally on the _under_ side, then
carefully removing its contents, and stuffing it with cotton. In the
former, a small straw or stalk of hay may be used, which will prevent
the fractures to which that part, when dry, is so liable. _Spiders_,
and a few _apterous_ genera, as well as almost all _larvæ_, as they
usually shrink up, in drying, into a shapeless mass, destitute of
every character dependent on colour or form, require to be preserved
in a different manner. They may all be very well kept in rectified
spirits of wine mixed with water, in the proportion of three parts of
the former to one of the latter. Each, suspended by a thread, should
be put in a separate very small labelled phial. Larger spiders, such
as _Mygale aviculare_, &c., when suffered to dry, though the abdomen
shrinks, do not wholly lose their characters, and are often kept in
cabinets: but if preserved in spirits, they may be put into larger
wide-mouthed bottles, suspended at different heights, with a label on
the outside opposite to each species. Mr. Abbott of Georgia had an
excellent method of preserving _caterpillars_, so that his specimens
retain their colours and other attributes, and look as if they were
alive. I am not acquainted with his process, but the following will
answer very well.--The animal must first be killed by immersion in
spirits of wine; next you must eviscerate it, which is best effected
by gradual pressure of the finger and thumb. You must begin at the
head, and so proceed till all the fluid contents of the body have
passed out at the anus, which you may enlarge with a fine pair of
scissors, being careful not to injure the anal prolegs. When you have
cleared the skin as much as possible, introduce a fine glass tube, or
a piece of hay or slender straw into the anus, round which, as near
to the extremity as may be, pass loosely a fine thread: then blowing
through the tube, when the skin is fully inflated withdraw it, at the
same time pulling the thread tight and securing it by a knot. The
caterpillar will now exhibit its proper shape and colours; to retain
which, all that is necessary is to hold it near the flame of a lamp
until perfectly dry, which will be in a few minutes, when it may be
placed in the cabinet along with the imago to which it belongs[1575].
* * * * *