much interesting and instructive matter connected with the caterpillar
and chrysalis, to which stages only brief reference can here be made.
The Caterpillar.
The second stage is that of the caterpillar, and in some species, such
as the Red Admiral, this is of very short duration, a few weeks only,
whilst in others, as for example the Small Blue, it usually lasts for
many months. There is considerable diversity both in the shape and,
where it is present, in the hairy or spiny clothing (_armature_) of
caterpillars. All, however, are alike in one respect, that is the body
is divided into thirteen more or less well-defined rings (_segments_),
which together with the head make up fourteen divisions. In referring to
these body-rings, the first three nearest the head, each of which is
furnished with a pair of true legs (_thoracic legs_), are called the
thoracic segments, as they correspond to the thorax of the perfect
butterfly. The remaining ten rings are the abdominal segments; the last
two are not always easily separable one from the other, and so for all
practical purposes they may be considered only nine in number. These
nine rings, then, correspond to the abdomen of the future butterfly. The
third to sixth of this series have each a pair of false legs
(_prolegs_), and there is also a pair on the last ring; the latter are
the anal claspers.
The warts (_tubercles_) are the bases of hairs and spines, and are to be
seen in most butterfly caterpillars, but they generally require a lens
to bring them clearly into view. These warts are usually arranged in two
rows on the back (_dorsal series_) and three rows on each side (_lateral
series_).
All the various parts referred to, or to be presently mentioned, may be
seen in Fig. 1, which also shows a peculiarity that is found in very
young caterpillars of the Orange-tip, and in some others of the "Whites"
(_Pieridæ_). The odd thing about this baby caterpillar is that the fine
hair arising from each wart is forked at the tip (Fig. 1, _a_), and
holds thereon a minute globule of fluid. When the caterpillars become
about half grown these special hairs are lost in a general clothing of
fine hair. Fig. 1, _b_, represents a magnified single ring of the
caterpillar, and this shows a spiracle and the folds of the skin
(_subsegments_). The manner in which such folding occurs is to be
observed in the higher study of larval morphology.
[Illustration: FIG. 1.
Young caterpillar of Orange-tip highly magnified.
(_After Sharp._)]
On each ring, except the second (including now the three thoracic with
the nine abdominal; and so making twelve rings), the third, and the
last, there is an oval or roundish mark which indicates the position of
the breathing hole (_spiracle_). Through these minute openings air
enters to the breathing tubes (_tracheæ_), which are spread throughout
the interior of the caterpillar in a seemingly complicated kind of
network of main branches and finer twigs; air is thus conveyed to every
part of the body. In the event of one or two air-holes becoming in any
way obstructed, the caterpillar would possibly be none the worse; but if
all the openings were closed up effectually, it would almost certainly
die. Total immersion in water, even for some hours, is not always fatal.
Turning again to the "feet" of the caterpillar, it will be seen from
the figure that the true legs (_a_) differ from the false legs (_b_) in
structure. The former are horny, jointed, and have terminal claws; the
latter are fleshy, with sliding joints, and the foot is furnished with a
series of minute hooks which enable the caterpillar to obtain a secure
hold when feeding, etc. The false legs are also the chief means of
locomotion, as the true legs are of little service for this purpose. The
true legs, however, appear to be of use when the caterpillar is feeding,
as the leaf is held between them so as to keep it steady whilst the jaws
are doing their work.
[Illustration: FIG. 2.
(_a_) True and (_b_) false legs.]
[Illustration: FIG. 3.
_a_, labrum; _b_, mandible; _c_, antenna; _d_, ocelli; _e_, maxilla;
_f_, labium; _g_, spinneret; _h_, labial palp.]
In the accompanying figure of the head of a caterpillar the mouth parts
are clearly shown. The biting jaws (_mandibles_) are slightly apart,
above them is seen the upper lip (_labrum_), and below them is the under
lip (_labium_ or _lingua_). The _maxillæ_ are very tiny affairs, but
they should be noted because in the butterfly they become the basal
portions of the two tubes which, when united together, form the sucking
organs (_proboscis_). The eyes, or ocelli as they are termed, are
minute, and are said to be of slight use to the caterpillar as organs of
sight, so that it probably has to depend on its little feelers
(_antennæ_) for guidance to the right plants for its nourishment.
Attention should also be given to the spinneret, as it is by means of
this that the silken threads, etc., for its various requirements are
provided; the substance itself being secreted in glands placed in the
body of the caterpillar. The palpi are organs of touch, and seem to be
of use to the caterpillar when moving about.
Immediately after hatching, many caterpillars eat the egg-shell for
their first meal; they then settle down to the business of feeding and
growing. It should be remembered that it is entirely on growth made
whilst in the caterpillar stage that the size of a butterfly depends. In
the course of a day or two the necessity arises for fasting, as
moulting, an important event, is about to take place. Having spun a
slender carpet of silk on a leaf or twig, the caterpillar secures itself
thereto, and then awaits the moment when all is ready for the
transformation to commence. After a series of twistings from side to
side and other contortions, the skin yields along the back near the
head, the head is drawn away from its old covering and thrust through
the slit in the back, the old skin then peels downwards whilst the
caterpillar draws itself upwards until it is free. The new skin,
together with any hairs or spines with which it may be clothed, is at
first very soft. In the course of a short time all is perfected, and the
caterpillar is ready to enter upon its second stage of growth. At the
end of the second stage the skin-changing operation is again performed,
and the whole business is repeated two or more times afterwards.
Finally, however, when the caterpillar has shed its skin for the last
time, the chrysalis is revealed, but with the future wings seemingly
free. These, together with the other organs, are soon fixed down to the
body by the shell, which results from a varnish-like ooze which covers
all the parts and then hardens.
Generally speaking, newly hatched caterpillars, though of different
kinds, are in certain respects somewhat alike, but the special
characters of each begin to appear, as a rule, after the first change of
skin (_ecdysis_), and these go on developing with each successive stage
(_stadium_) until the caterpillar is full grown. The form assumed in
each stage is termed the _instar_, therefore a caterpillar just from the
egg would be referred to as in the first instar; between the first and
second changes of skin, as in the second instar, and so on to the
chrysalis, which in the case of a caterpillar that moulted, or changed
its skin, four times before attaining full growth, would be the sixth
instar, and the butterfly would then be the seventh instar. In practice,
however, it is usually the stages of the caterpillar alone that are
indicated in this way.
The Chrysalis.
The term _chrysalis_ more especially applies to such of them as are
spotted or splashed with metallic colour, as, for example, the
chrysalids of some of the Fritillaries. The scientific term for the
chrysalis is _pupa_, which in the Latin tongue means "a doll or puppet."
[Illustration: FIG. 4.
Caterpillar of Small White, about to change to chrysalis.]
In passing to the chrysalis stage the caterpillars have sometimes to
make rather more preparations than in previous skin-changing provisions.
Those of the Swallow-tail, Whites, Orange-tip, and similar kinds have to
provide a silken girdle for the waist as well as a pad for the tail.
Chrysalids that hang suspended, head downwards, such as the Vanessids,
Fritillaries, etc., are attached by the cremaster--a hooked arrangement
on the tail (Fig. 5)--to a pad of silk; others, such as the Blues and
the Coppers, appear to be held in position on a leaf, or some other
object, by means of a fine girdle of silk, or sometimes a few silken
threads spread net-like above and below them--rudiments of a cocoon in
fact. Chrysalids of the Skippers are enclosed in a more or less complete
cocoon placed within a chamber, formed of a leaf or leaves of the
food-plant, drawn together by silken cables. Some of these chrysalids
are furnished with hooks on the tail as well as with a girdle for
suspension; but others have hooks only.
As almost all the chrysalids here considered are figured in the
illustrations, it will be unnecessary to refer in detail to their great
diversity in form, but a few general remarks on the structure of a
chrysalis may be made.
[Illustration: FIG. 5.
Enlarged view of cremaster, and a hook still more enlarged.
(_After Sharp._)]
If the upper (_dorsal_) surface of a chrysalis is examined, the thorax
and the body divisions will easily be made out, while, by looking at the
sides and the under (_ventral_) surface, the various organs, such as the
wings, legs, antennæ, etc., will be found neatly laid along each side of
the "tongue," or proboscis, which latter extends down the centre. All
these are separately encased, but by reason of the shell mentioned in
the remarks on the caterpillar, they appear to be welded together. When,
however, the butterfly is ready to emerge, the shell of the chrysalis is
split along the thorax and at the lower edge of the wing-cases, and the
insect is then able to release itself from the pupal trappings. This
breaking open of the chrysalis shell is termed dehiscence (_dehisco_,
"to split open"), and the manner in which it is effected varies in
different species. The emergence of a butterfly from the chrysalis is
always an interesting operation to observe, and every one should make a
point of watching the process, so that he may obtain practical knowledge
of how the thing is done. A photograph of it will be found in the
description of the Wall Butterfly.
The Butterfly.
Having safely cleared itself free of the chrysalis shell, the butterfly
makes its way to some suitable twig, spray, or other object, from which
it can hang, sometimes in an inverted position, whilst a very important
function takes place. This is the distention and drying of the wings,
which at first are very weak and somewhat baggy affairs, although the
colour and markings appear upon them in miniature. All other parts of
the butterfly seem fully formed, but the helpless condition of the wings
alone prevent it as yet from floating off into the air. In a remarkably
short time, after the insect has settled to the business, the fluids
from the body commence to flow and circulate through the wings, and
these are seen gradually expanding and filling out until they attain
their proper size. Occasionally there is some obstruction to the equal
distribution of the fluids, and when this occurs a greater or lesser
amount of distortion, or cockle, in the wing affected is the result.
When the inflation is completed the wings are kept straight out for a
time; they are then motionless, but all their surfaces are well apart.
The wings being now fully developed, the further flow of fluid appears
to be arrested. It has been stated by some authorities that this fluid
is fibrin held in solution, and that when the work of expansion has been
accomplished, the watery medium evaporates, leaving the fibrin to
harden, and so fasten together the upper and lower membranes of the wing
and to fix the veins, or nerves, in their proper position. Mayer, a
specialist on these matters, referring to the expansion of the wings,
remarks that the blood [the fluid previously mentioned] forced into the
freshly emerged wing would cause it to become a balloon-shaped bag if it
were not for fibres that hold the upper and lower walls closely
together. The fibres referred to, he states, are derived from those
hypodermic cells which do not contribute to the formation of scales, but
are stretched out from one wall of the wing to the other.
It may be well now to briefly consider some of the structural details
of the perfect butterfly, so a beginning will be made with the head
(Fig. 6). When looking at the head of a butterfly, the first thing to
attract the attention is the very large size of the compound eye (_a_),
which seems to take up the largest share of the whole affair. Although
so bulky and so complex in the matter of divisions, or facets, as they
are termed (the facets are not shown in figure), the power of sight is
not really very keen. A butterfly can see things in a general way
readily enough, but it seems unable to clearly distinguish one object
from another. When engaged in egg-laying, the female butterfly rarely
fails to place her eggs on a leaf or spray of the plant that the future
caterpillar will feed upon, and it has been suggested that in making
this unerring selection the insect is guided more by the sense of smell
than by that of sight.
[Illustration: FIG. 6.
=Head of Butterfly.=
_a_, compound eye; _b_, palp; _c_, antenna; _d_, proboscis.]
The horns (_c_) (_antennæ_), or feelers, as they are sometimes called,
which adorn the head, are now considered to be organs of smell. These
are composed of a number of rings or segments, which vary in the
different kinds of butterfly, as also does the shape of the terminal
rings forming what is known as the club. In Fig. 7, _e_ (Purple Emperor)
and _f_ (Marbled White) represent the gradually thickened club; in _g_
(Brimstone) and _h_ (Dark-green Fritillary) the clubs are more or less
abruptly formed. Our Skippers have well-developed clubs; these may be
hooked at the tip as in _i_ (Large Skipper), or blunt at the tip as in
_j_ (Chequered Skipper); at the base of the Skipper's antenna, that is
at the point where it is inserted in the head, there is a tuft of rather
long hairs.
Of the various mouth parts it will only be necessary to refer to the
suction-tube, Fig. 6, _d_ (_proboscis_), often called the "tongue,"
which is perhaps the most important, at least to the butterfly itself,
as this organ is, in a way, as useful to it in the perfect state as were
the very differently constructed strong biting jaws (_mandibles_) of its
caterpillar existence. These latter in the butterfly are only
microscopically represented, and the suction-tube of the perfect insect
is an extension of the maxillæ, which in the caterpillar are not
conspicuous. When not engaged in probing the nectaries of flowers for
the sweets they contain, the suction-tube is neatly coiled up between
the palpi (Fig. 6, _b_). Its great flexibility is due to the many rings
of which it is composed. Although seemingly entire, it is really made up
of two tubes, each being grooved on its inner side, and forming, when
the edges are brought together, an additional central canal, through
which the sweets from the flowers and other liquids are drawn up into a
bulb-like receptacle in the head, whence it passes into the stomach.
When it is remembered that the passage of sweet, and no doubt sticky,
fluid through the central tube would most probably result in its walls
becoming clogged, there is reason to suppose that the method of
construction permits of the canal being cleansed from time to time.
[Illustration: FIG. 7.
=Antennæ of Butterflies.=]
The important divisions of the body are the thorax and the abdomen. The
former is made up of three segments (named the pro-, meso-, and
meta-thorax), each of which, as in the caterpillar state, is furnished
with a pair of legs; the second and third, which are closely united,
each bear a pair of wings also. The legs, which in the butterfly are
adapted for walking at a leisurely pace, are made up of four main parts;
these are (a) the basal joint (_coxa_, _coxæ_), (_b_) the thigh
(_femur_, _femora_), (_c_) the shank (_tibia_, _tibiæ_), and (_d_) the
foot (_tarsus_, _tarsi_). The small joint uniting the coxa with the
femur is the trochanter (_tr._). The foot usually has five joints, the
last of which is provided with claws (_e_). The abdomen really consists
of ten rings or segments according to some specialists. Examined from
above, the female butterfly appears to have only seven rings and the
male butterfly eight. This discrepancy arises from the fact that in the
former sex two rings and in the latter one ring are withdrawn into the
body, and so are tucked away out of sight. The organs of reproduction
are placed in the terminal ring. The breathing arrangements are pretty
much as in the caterpillar, but the external openings are not so
apparent owing to the dense clothing of the body.
[Illustration: FIG. 8.
=Leg of Butterfly.=]
The beauty of a butterfly's wings is intimately connected with the form
and colour of the scales with which they are covered, as with a kind of
mosaic; but before the scales and their method of attachment, etc., are
referred to, something should be said about the wings themselves. The
various shapes of these organs of flight will be seen on turning to the
plates, where will be found accurate portraits of every species that
will be dealt with in the descriptive section later on.
A butterfly's wing consists of an upper and a lower membrane, with a
framework of hollow tubes, acting as ribs, between the two layers. Fig.
9, A, shows a fore and a hind wing of the Swallow-tail butterfly. The
point of attachment with the thorax is the base of the wing, and the
edge farthest from the base is the outer margin (_termen_); the upper
edge, or front margin, is the costa; and the lower edge is the inner
margin (_dorsum_). The point where the upper margin meets the outer
margin on the fore wing is the apex, but on the hind wing it is called
the outer angle; the angle formed by the junction of outer and inner
margins is the inner angle of the fore wing, but the anal angle of the
hind wing. The term _tornus_ is sometimes used for this angle on either
wing. Dividing the wings transversely into three portions, we have three
areas, termed respectively basal, central or discal, and outer. These
are terms used in descriptions of butterflies, and it will be useful to
remember them.
[Illustration: FIG. 9.
=Butterflies' Wings.=]
The ribs of a butterfly's wings are by some authors described as veins,
whilst others style the main ones nervures, and the branches nervules.
Fig. 9, B, represents the venation, or neuration of the Black-veined
White, and the numeral system of indicating the veins has been adopted,
as it is the most simple. In another method of referring to the
venation, and one that has been much in use, vein 12 of the fore wing
would be styled the costal nervure, or vein; veins 11, 10, 9 (absent in
figure), 8, and 7 would be the subcostal nervules 1, 2, 3, 4, and 5; 6
would become the upper radial, and 5 the lower radial; 2, 3, and 4 would
be the median nervules 1, 2, and 3; vein 1 would be the submedian
nervure, or vein. On the hind wing, vein 1_a_ would be the internal
vein; 1 the submedian; 2, 3, and 4 the median nervules; 5 the lower and
6 the upper radials; 7 the subcostal, and 8 the costal nervures. Just
near the base of the hind wing will be noted a short recurved vein
(p.c.); this is the precostal vein, and so named because it comes before
the costal. It is always absent in some species. Comparing the venation
of A and B, it will be seen that in A the fore wing has 12 veins and the
hind wing 8 veins, whilst in B there are only 11 veins on the fore wing,
but the hind wing has one vein more than that of A. In the Black-veined
White, vein 9 is absent on the fore wing, and on the hind wing there is
one internal vein.
[Illustration: FIG. 10.
=Arrangement of Scales.=
(_After Holland._)]
Dust-like as they appear to the naked eye, the scales from a
butterfly's wing seen under the microscope are found to be exceedingly
interesting structures and very varied in shape. Dr. Sharp describes
them as "delicate chitinous bags." Chitin, it may be mentioned, is the
horny substance of which the chrysalis shell is formed, and this was
adverted to when discussing the chrysalis stage as a varnish-like ooze.
As seen on the wings, the scales are flattened and the upper and under
sides are then almost, or quite, brought together. They are attached in
lines on the membrane or covering of the wing by short stalks which fit
into sockets in the membrane. The arrangement of the scales, which has
often been stated to resemble that of the slates on a roof, is shown in
Fig. 10.
Colour is chiefly due to pigment contained in the scale or adhering to
the interior of its upper side. Pigments, according to Mayer, are
derived, by various chemical processes, from the blood while the
butterfly is still in the chrysalis. Some scales have minute parallel
lines (_striæ_) on their upper sides, and rays of light falling on these
are turned aside or broken up, and so produce changes in the colouring
of a wing, according to the angle from which it is looked at.
The males of many kinds of butterfly have special scales, which are
known as androconia, or plumules. It is believed that these are scent
organs. Whatever their particular use may be to the possessor, these
androconia enable the entomologist to distinguish male specimens from
females with great certainty. In the Fritillaries they are placed on one
or more of the median nervules (veins 2, 3, and 4) of the fore wing. In
the Meadow Brown and its kindred they form brands on the disc of the
fore wing. In the Skippers they are placed in a fold of the costa in
some species, and in other species they are clustered together, into
more or less bar-like marks, about the middle of the fore wings. Some of
these various shaped "plumules" are shown in the illustrations.
In the foregoing sketch of the life cycle of a butterfly, the object
has been to condense as much necessary information as possible into a
limited space. Many matters of importance to the student have not been
touched on, but it was considered that, as these were more especially
connected with a higher scientific phase of the subject than would here
be found helpful, they might be omitted.
[Illustration: FIG. 11.
=Butterfly Plumules.=
_a._ Tufted Plumule (Satyrs);
_b._ Bristle Plumule (Grizzled Skipper);
_c._ Hair Plumule (Dingy Skipper);
_d._ Jointed Plumule (Silver-studded Skipper);
_e._ Bladder Plumule (Common Blue);
_f._ Dotted Plumule (White-letter Hairstreak).
(_After Aurivillius._)]
Collecting.
Naturally the first matter for consideration, when the formation of a
collection of butterflies has been decided upon, is how to set about it.
Well, there are two methods of effecting our purpose. The specimens may
be purchased from a dealer in such things, or we may acquire an outfit
comprising net, boxes, and pins, and go in search of the insects
ourselves. Apart from its healthful and entertaining possibilities, the
latter method has very much to recommend it. In the first place, those
who are at all observant--and no true lover of Nature can be suspected
of being otherwise--will become acquainted with the objects under
natural conditions, and so be enabled to appreciate them more highly
than could be the case if they were obtained in any other way. The chief
purpose in making a collection of Natural History specimens should be
study of some kind rather than mere accumulation.
[Illustration: FIG. 12.
=Y-piece.=]
[Sidenote: Nets.]
The net may be a simple cane ring one of home construction, or the more
elaborate, but not necessarily more efficient, fabrication of
steel-jointed ring with grenadine bag and telescopic handle. A good
serviceable butterfly-net may be fitted up as follows. Procure a light
flexible cane, about 3 feet or so in length. Next, a Y-shaped holder
(Fig. 12) for the two ends of the cane will have to be made, and either
tin or brass may be used for the purpose. The latter is the better
metal, and the parts should be brazed and not soldered together. (If
difficulty is experienced in the manufacture of this article, it may be
obtained from any dealer in entomological requisites for a few pence.)
The bag may be made of leno, tarletan, or fine mosquito netting; the
latter is the most serviceable, and should be used wherever it can be
obtained. The size of the bag at the top, where it has a wide band to
take the cane, should not exceed the circumference of the cane ring when
fitted in the two arms of the Y-piece; the depth should be just a little
less than the length of one's arm, and the bottom should be rounded off
so that no corners are available for the butterflies to get into and
damage their wings. An opening about 3 inches in length is left in the
seam of the bag just under the Y-piece, so that the cane may be removed
and rolled up when the net is put out of action. The ring band should be
covered with some stouter material to prevent it from fraying, thin
leather is sometimes used for this purpose; the slit in the seam also
requires protecting on each side, and strengthening at the lower end by
a crosspiece. An ordinary walking-stick, with the ferrule end thrust
into the longer tube of the Y, will serve as a handle to the complete
net.
[Illustration: FIG. 13.
=Kite or Balloon Net.=]
The dealers adverted to above generally stock a variety of nets ready
fitted for use. Among these is a very useful pattern known as the kite
or balloon net (Fig. 13). This is made in two sizes, and as the writer
has used this kind of net for at least twenty years, he is able to speak
well of its merits. It does not need a stick for ordinary work, and the
long end of the socket should be about 9 inches in length.
The "ring" being made of four separate rods, in addition to the Y-piece,
some care will have to be taken when a balloon net is unshipped. It will
be found a good plan to leave the two short curved canes in the hem or
band of the bag, remove the two straight arms from the Y-piece and the
band, place these on top of the bag when folded, and then roll all up
together. A canvas or linen pouch or pocket, opening at one end, may be
made to contain the whole affair.
The umbrella-net, when in its case, looks very like the familiar "gamp."
Its chief merit is that it is quickly put up for use, and its principal
defect is that the stick, which crosses the mouth of the bag, frequently
damages the quarry.
Another implement of the chase known as the "Ortner" net is used pretty
extensively on the Continent. English entomologists who have used it
speak of it most favourably. Its great advantage over other nets is
found in the simple and rapid method of its adjustment for use.
In connection with nets it may be well to advise the wielder to remember
that carrying a threaded needle is a useful practice. Tears and rents
are apt to occur, and it is well to have the means of repair handy.
[Sidenote: Killing.]
Some collectors seem to be expert at killing butterflies by pressing the
sides of the thorax together. The method is not, however, as
satisfactory as one could wish, and so no more need be said about it.
For the happy despatch of insects, the cyanide bottle is frequently
used. All that has to be done is to clap the open bottle over the
captive while still in the net, then draw the gauze or what-not over the
mouth of the bottle until the bung can be inserted, and the whole affair
withdrawn from the net.
Cyanide of potassium is a deadly poison, and no inexperienced person
should attempt to charge a cyanide bottle himself. In fact, chemists are
not permitted to supply the poison to unknown customers. Under certain
conditions, however, a chemist might consent to make up a killing
bottle, and the following instructions may help him in doing this. A
fairly strong, clear glass bottle, holding about 4 to 6 ounces; the
mouth must be pretty wide, and closed with a well-fitting bung that has
been dipped in melted wax; if the bung is of fine grained cork, the wax
will not be needed. At the bottom of the bottle place a thick layer of
the cyanide, and over this pour plaster of Paris which has been mixed
with water and converted into a cream-like paste: one-third of the depth
of the bottle to be occupied by the poison and plaster, but only a thin
layer of the latter should cover the former.
Dealers who supply cyanide bottles (uncharged) also have in stock a
brass bottle for chloroform, which some people prefer as a killing agent
because it does not change the colour of insects as cyanide is
occasionally apt to do. In using this, the insect should be boxed, then
a drop of the chloroform may be allowed to run from the bottle over the
perforated lid or bottom of the box, and a finger put over the hole or
holes for a short time.
The majority of butterflies, if transferred to pill boxes from the net,
settle down quietly. In this way they may be taken to one's home and
there placed, boxes and all, into the ammonia jar, a simple but very
effective contrivance. To start one of these lethal chambers, procure a
good sized pickle jar, one of the brown earthenware kind, holding about
2 gallons. At the bottom put in several layers of stout blotting-paper,
and have ready a covering for the mouth of the jar. This covering may be
of skin, waterproof-apron material, or even thick brown paper. Before
turning the boxes into the jar, lift up the blotting-paper, drop in
about half a teaspoonful of strong liquid ammonia (·880) and replace
blotting-paper. Directly the boxes are in the jar, put on cover and tie
it down securely. If brown paper is used, a piece of pasteboard should
be put over it and a weight on top of that. Suffocation takes place
directly the gas reaches the insect, but it often happens that one or
more of the boxes exclude the gas longer than others. At the end of half
an hour all may be removed, but the insects will not hurt in any way if
left in all night.
The best kind of boxes for field work are those known as "glass
bottomed," as in these the captives can be examined and, if not wanted,
may be set free. It is always better to retain only those specimens that
we know are really useful, rather than to incur the necessity of
throwing away insects after we have deprived them of life.
[Sidenote: Pinning.]
If butterflies are pinned on the spot, a collecting box will be
required, and the most useful and convenient is one of an oval shape.
This should be made of zinc, and lined with cork that is held in place
by zinc clips. The cork should be kept damp when in use, and the water
used for damping should have a few drops of carbolic acid mixed with it
so as to prevent the formation of mould. Insects may remain in such a
box for several days without injury. This box will also be useful for
relaxing specimens that have been badly set, or have been simply pinned
during the busy season.
In the matter of pins, it is not altogether easy to make suggestions.
There are, perhaps, only two makers in this country of entomological
pins, and each of these supplies a large number of sizes. The selection
of suitable pins will largely depend on the method of setting adopted.
Black pins are, however, the best for butterflies, and are now used
almost exclusively.
In pinning a specimen care should be taken that the pin passes in a
direct line through the centre of the thorax. Insects that are properly
pinned set better, and have a neat appearance when arranged in the
collection. For regulating the height of specimens on the pin, a handy
graduated stage has been devised by Dr. Scarancke (see Fig. 14). Each of
the little rests are hollowed to receive the body of the insect, so
suppose we wish a quarter of an inch of the pin to show below the body
of a specimen, the pin is pushed through a perforation in the centre of
the rest groove marked "3/16" until the point touches the wooden base,
and we have the required length.
Beginners would, perhaps, find three sizes of pins quite sufficient for
almost every purpose--say, Nos. 10, 8, and 5 of one maker; or Nos. 9,
17, and 5 of the other. In each case the first size pin would be
suitable for small butterflies, the second size for all other
butterflies except quite the largest, for which No. 5 would remain.
English pins are sold by the ounce.
[Illustration: FIG. 14.
=Pinning Stage.=]
[Sidenote: Setting.]
Setting, as it is called, that is, spreading out and fixing the wings
so that all their parts are displayed, arranging the horns, etc., is
perhaps the most tedious work that the collector will be called upon to
perform. The various methods will be referred to, and he must then
decide as to which he will adopt. Each style may possibly be found to
have its difficulties at first; but time and patience will overcome
these, therefore he must be prepared for a good deal of troublesome
practice before he quite gets "the hang of the thing," and can set out
his specimens without removing a greater or lesser number of the scales.
First, as to the flat and high setting as practised by almost every
lepidopterist abroad and by some in our own country. Boards of the
pattern, shown in the illustration, will be required; also some tracing
cloth, and a pair of entomological forceps, bead-headed pins, etc. In
these boards, it will be noticed, the sides tilt outwards; this is to
allow for drooping of the wings, which generally occurs after insects
are removed from the "sets." In this case the wings would settle dead
flat, which is considered to be the acme of perfection in this style of
setting. Carlsbad or other foreign pins would be used for this kind of
work. They are of a uniform length, about one inch and a half, but vary
in thickness, and are usually sold by the 100 or 1000.
[Illustration: FIG. 15.
=Board for Flat-setting.=]
Manipulation of the specimen on these boards is as follows. Having
carefully pinned it, leaving the greater length of pin below the insect,
guide the pin carefully through the narrow opening (_a_ Fig. 15) and the
cork (Fig. 16) below to a suitable depth, so that the body of the insect
rests in the groove and the wings lie easily on the board. Then take two
strips of tracing cloth, glazed side downwards, and pin them on at the
end of each side of the setting-board (Fig. 17). The strip should be
just wide enough to cover all but the basal part of the wings. Now pass
the strips over the wings, press one side lightly with the fingers of
the left hand while the wings are moved into position with the setting
needle (a fine needle with eye end fixed into the stick of a small
penholder will do for this) from the uncovered base, a pin being
inserted below the fore wing while the hind wing is brought into
position, but when this has been done and another pin inserted to keep
it in place, as shown in the diagram, the first pin may be removed;
repeat the same operation on the other side. Other pins will be required
to keep the horns, etc., in place. In dealing with the next specimen the
strips will have to be turned back while it is fixed into position, then
proceed as before. An imaginary line following the inner margin of the
fore wings and passing through the pin on the thorax is an excellent
guide to uniformity in setting. The groove will prevent the pin leaning
to either side, but care should be taken that it does not incline either
forwards or backwards. The strip of tracing cloth may be used more than
once, but the roughness of the pin holes should be removed by drawing
the strip across the back of a knife.
[Illustration: FIG. 16.
=Longitudinal Section of Setting-board.=]
[Illustration: FIG. 17.
=Setting-board in use.=]
[Illustration: FIG. 18.
="Saddle" Setting-board.=]
[Illustration: FIG. 19.
=Setting-bristle.=]
[Illustration: FIG. 20.
=Brace and Band Modes of setting.=]
The setting-boards most frequently used in this country have sloping
sides, and are known as saddles (Fig. 18). Where tracing cloth is used,
the _modus operandi_ is exactly similar to that just described, but
small pins will do for pinning down the strips, as the saddles are made
of cork, or cork carpet, instead of wood.
The following method of setting butterflies on the English kind of
"board" or saddle is frequently adopted. Select a suitable saddle, that
is one that has the groove wide enough to take the body, and rather
wider than the wings when expanded. A setting bristle will then be
required. This is made, as shown in Fig. 19, by fixing a fairly long and
stout bristle, or a very fine needle, or a thin length of quill, in a
cube of cork; the cork cube has a stoutish and sharp-pointed pin pushed
through it as indicated. Having placed the first insect on the saddle
with its body comfortably resting in the groove and the wings flush with
the surface, the setting bristle is then brought into action. The point
of the pin is rested on the saddle directly in the rear of the hind
wing, and the top of the bristle touching the saddle in advance of the
front wing. Tilt the pin slightly forward until the bristle presses
lightly on the central area of the wings, then with the setting needle
push the wings into the required position, and at the same time drive
pin of bristle into the saddle. After the wings have been secured by
means of braces (triangular pieces of thin card or stout paper, with a
pin through the base of the triangle), proceed in the same way with the
other side. Finally, fix a brace to the tip and angle of each fore wing
to keep them from turning up in drying, and a pin or two may be required
for the horns if these are not in a good position. Instead of using
braces, a strip of transparent paper may be pinned over the wings beyond
the bristle, but in this case the bristle must be pressed across the
wings at a point nearer their base than in the previous method (see
lower figure in Fig. 20). In lieu of a setting bristle a length of
sewing cotton may be used. Tie a double knot at one end, and through
this pass the point of a pin in such a way that the cotton lies flush on
the saddle when in use. Insert the pin firmly in the saddle a little in
advance of the fore wing, then draw the cotton downwards across the
wings and hold it taut, with the fore finger of the left hand placed on
it just in rear of the hind wing. Whilst so held the wings can be got
into pose with the setting needle, and braces may then be applied as
previously directed.
Fig. 21 shows a specimen set by a method that is in vogue in the north.
Blocks of soft pine, grooved and bevelled as in the cork saddle, are
easily made. Down the centre of the groove there is a saw cut for the
point of the pin to enter, and nicks are cut along the bottom edge at
each end. One end of a length of cotton is knotted and fixed in a nick,
then a turn is taken over the wings on one side; these are placed in
position and secured by other turns of the cotton. The other side is
then treated in the same manner, and the end of the cotton fastened off
in one of the nicks. This is a quick and, in skilled hands, a very neat
method.
As specimens after being set will have to remain on the setting boards
or saddles for at least a fortnight, it will be necessary to protect
them not only from dust, but from possible attack by ants, cockroaches,
mice, etc. This is best ensured by placing the sets into a receptacle
called a setting or drying house. Dealers supply these, but the young
collector may have a knowledge of carpentry and could make one for
himself. The height and depth of such a construction would depend upon
the number and the width of the boards or saddles that would be put
therein. The width would be that of the length of the boards, which is
usually 14 inches. About a quarter of an inch of cork is cut off each
end of the saddles, and grooves are cut in the sides of the house for
these to run in. The back and the door should have a square of fine
perforated zinc inserted in them for ventilation. As an example of
holding capacity it may be well to note that a house with a height of 12
inches, and a depth of 6 inches, inside measurement, would take eighteen
2-inch boards if the grooves were cut at 2 inches apart, or twenty-four
boards of same width if 1-1/2 inch only were allowed between the
grooves.
[Illustration: FIG. 21.
=Cotton Method of setting.=]
In taking insects off the sets, the braces or strips should be removed
from the wings, and the pins from the horns, with care, as a good deal
of damage can be done in the performance of this operation, simple as it
seems to be. A little twist of a brace and away goes a patch of scales,
a side slip of a pin and off comes a horn.
Pending the arrival of that twelve or twenty drawer cabinet, the
beginner will probably be content to arrange his specimens in boxes. A
handy sized box is one measuring 14 inches by 10 when closed, and it
should have a cell for naphthaline.
Before putting the specimens away into boxes or drawers they should be
labelled with the date of capture, the locality, the name of the captor,
and any other detail of interest in connection with it. All these
particulars may be written on small squares of paper and put on the pins
under the specimens.
Cabinets or boxes containing insects should always stand where they are
free from damp, otherwise mould may make its appearance on the
specimens. Mouldy insects may be cleaned, but they never look nice
afterwards; so it will be well to bear in mind that prevention is better
than cure. Where drawers and boxes are not properly attended to in the
matter of naphthaline, mites are apt to enter and cause injury to the
specimens. If these pests should effect a lodgment, a little benzine
poured on the bottom of box or drawer will quickly kill them. The
benzine, if pure, will not make the least stain, and of course the
drawer or box must be closed directly the benzine is put in. Do this
only in the daytime.
Rearing butterflies from the egg is much practised, and is a very
excellent way. One not only obtains specimens in fine condition, but
gains knowledge of the early stages at the same time. The eggs of most
of the Whites, the Orange-tip, the Brimstone, and some others are not
difficult to obtain, but searching the food-plants for the eggs of many
of the butterflies is tiresome work, and not altogether remunerative.
Females may be watched when engaged in egg-laying, and having marked the
spot, step in when she has left and rob the "nest." The best plan is to
capture a few females and enclose them in roomy, wide-mouthed bottles,
or a gauze cage, putting in with them a sprig or two of the food-plant
placed in a holder containing water. The mouth of the bottle should be
covered with gauze or leno, and a bit of moistened sugar put on the top
outside. Either bottle or cage must be stood in the sunshine, but it
must be remembered that the butterflies require plenty of air as well as
sunshine, and that they can have too much of the latter.