Hard-bodied insects, such as beetles, flies, and wasps, are preserved as
dry specimens on pins better than in fluid. The pinned specimens are
more convenient to study and they retain their natural coloring better.
Flies and butterflies are covered with hairs or scales that clot or
break off if the specimens are preserved in fluid, and for this reason
they should be pinned.
[Illustration: Fig. 11.--Pinning. Medium- to hard-shelled insects
are mounted by being pinned through the body in the manner shown at
_a_. The black spots show the location of the pin in the case of
bees, flies, and wasps, _b_; stink bugs, _c_; grasshoppers, _d_; and
beetles, _e_.]
Common household pins are too thick and short for pinning insects.
Longer, slender pins called insect pins are necessary and may be
purchased from various supply houses. They should be of spring steel; a
brass pin will corrode and be destroyed by acids in the insect's body.
The pins are available in numbered sizes, of which 1, 2, 3, and 4 will
be found of most general use, and sizes 0 and 00 of advantage in special
cases.
Medium to Large Insects.--Medium to large hard-shelled insects such as
moths, beetles, flies, bees, and wasps, should be pinned vertically
through the body, fig. 11_a_. It is essential that the pin pass through
a fairly solid part of the body, and, to insure this, the following
standard procedures should be adopted:
1. Bees, wasps, flies.--Pin through thorax between bases of front wings
slightly to right of middle line, fig. 11_b_.
2. Stink bugs.--Pin just to right of middle line of the scutellum or
large triangle between the bases of the front wings, fig. 11_c_.
3. Grasshoppers.--Pin through back part of prothorax (the saddle behind
the head) just to right of middle line, fig. 11_d_.
[Illustration: Fig. 12.--Pinning. Moths, _a_, and butterflies, _b_,
are pinned through the center of the thorax (instead of to the right
of the median line) between the bases of the front wings.]
[Illustration: Fig. 13.--Pinning block. The block is 1¼ x 1¼ x 2¼
inches, with holes drilled to the depths shown and having diameters
only slightly greater than the largest pin that will be used. A
specimen is pinned and the pin inserted into one of the holes until
the pin touches bottom; thus, insects may be pinned uniformly at a
desired height.]
4. Beetles.--Pin near front margin of right wing cover near middle line,
fig. 11_e_.
5. Moths, butterflies, dragonflies, damselflies.--Pin through the center
of the thorax between the bases of the front wings, fig. 12.
The insect should be pushed about three-quarters of the distance up the
pin, but not so close to the top that no room is left for easy handling
of the pin with the fingers. It is well to have all insects the same
distance from the top of the pin. To insure a uniform distance, the
collector should use a pinning block. This is a small piece of wood or
metal usually in the form shown in fig. 13, into the top of which are
drilled holes slightly larger than the pin diameters. Such a block may
be fashioned of wood with holes made by small nails and covered with a
cardboard rectangle through which have been stabbed holes the exact size
of those in the wood. The depths of the holes in the block should be
three-eighths inch, three-quarters inch, and 1-1/8 inches, respectively.
To use the block, pin the insect and insert the pin into whichever hole
allows the specimen to be pushed up the pin and still leave room,
allowing for the thickness of the insect's body, for handling at the
top.
[Illustration: Fig. 14.--Pinning small insects and labeling. The
insect may be glued to a card point, _a_, which has been crimped to
meet the right side of the body, _b_, _c_; or it may be pinned with
a minuten pin, _d_, to a piece of cork or pith, which in turn is
regularly pinned. All pinned insects should be labeled, as at _e_.
In the case of some small insects, such as tiny moths, the minuten
pin may be run down through the body and then into the cork; in the
case of others, such as mosquitoes, it is often desirable to run the
minuten pin up through the cork first and then impale the specimen
on the point of the pin.]
Tiny Insects.--Very small insects should be mounted on card points or on
minuten pins. Regular pins would break too many of the insects' body
parts.
Card points are small triangles of cardboard or plastic pinned through
one of the sides and crimped over at the opposite apex; a spot of strong
glue is put on the angled tip, and the right side of the insect is
pressed against the glued surface, fig. 14. The slant of the crimp
depends on the angle of the insect's side; the desired product is the
insect mounted with its top surface horizontal and its head forward;
legs, wings, and antennae should be in view and as little of the body as
possible hidden by the glue or card point. Very little glue should be
used; a small amount holds well and gives a better specimen for study
than a large amount. The points may be cut uniformly with a hand punch,
and they should be about three-eighths inch long. Good material for
making these points is 2-ply Bristol board.
[Illustration: Fig. 15.--Pinning crane flies. Because of their
unwieldy legs, these insects should have a double card point mount,
and the legs should be kept away from the pin so that they will not
be broken in handling.]
Minuten pins are short, extremely delicate steel pins, fig. 14_d_. One
of these is thrust through the body of the insect and into a small piece
of cork, pith, or similar substance, which is in turn pinned in the
regular way a card point is. This method is especially desirable for
tiny moths.
Insects Hard to Pin.--Wasps, lacewings, damselflies, and similar insects
have an abdomen that sags readily when the specimen is killed and
pinned. This unwanted drooping can be prevented in three simple ways.
(1) Stick the pinned insect on a vertical surface of a block so that the
body by its own weight dries in normal position. (2) Pin the insect on a
horizontal surface and run a stiff paper on the pin beneath the body in
such a way as to support it in a natural position until the insect
dries. (3) Brace the abdomen by crossing two pins beneath it and
thrusting them into the block, allowing the specimen to dry in the angle
of the cross.
Crane flies are unwieldy and so are best pinned on a double card point
mount, fig. 15. The legs should be directed away from the pin to avoid
breakage in handling.