B

A spreading board. A, cross section showing relation of cork strip to groove in center of board; B, a board containing a spread specimen. Supply-house boards are generally 12 in. long and 4 to 6 in. wide; the top pieces are % in. thick at the inner edge and J^ in. thick at the outer edge. The center groove may be 34 to in. or more wide, depending on the size of the insects to be spread on it; the width of this groove is adjustable in some supply-house boards. The top pieces should be of wood soft enough to take a pin easily.

A spreading board. A, cross section showing relation of cork strip to groove in center of board; B, a board containing a spread specimen. Supply-house boards are generally 12 in. long and 4 to 6 in. wide; the top pieces are % in. thick at the inner edge and J^ in. thick at the outer edge. The center groove may be 34 to in. or more wide, depending on the size of the insects to be spread on it; the width of this groove is adjustable in some supply-house boards. The top pieces should be of wood soft enough to take a pin easily.

grasp a pin containing a point by the sharp end, and touch the tip of the upper surface of the point to a drop of glue and then to the insect. Long and slender insects put on points should be put on 2 points that have their tips separated to form a V. Use glue or household cement, not mucilage.

Very small insects are sometimes mounted on "minuten" pins instead of points; they are short and very slender. Insert one end of the pin into the insect and the other into a small piece of cork on a regulation insect pin.

Spreading. The position of the legs and wings in a pinned insect is generally not important, as long as all parts can be seen and studied, but some insects (such as butterflies, moths, and perhaps some others) should have their wings spread before being put into the collection. An insect can be spread on a spreading board or spread upside down on a flat surface; the position of the wings depends on the type of insect. A spreading board (see illustration above), which can be bought from a supply house or can be homemade, is used for specimens going into a pinned collection. The specimens are usually spread dorsal side up. An insect to be mounted under glass, as in a Riker or glass mount (see pp. 19-20), is spread on any flat surface soft enough to take an insect pin and placed in an upside-down position. The spreading process consists of placing the wings in a standard position and fastening them there (with strips of paper), and leaving them to dry in that position.

The wings of a butterfly, moth, or other insect in which the front wings are more or less triangular are spread with the hind margin of the front wings at right angles to the body, and the hind wings far enough forward so that there is no large gap at the side between the front and hind wings (see illustrations of such insects in this book). In grasshoppers, damselflies, dragonflies, and other insects whose front wings are elongate rather than triangular, the wings are generally spread with the front edge of the hind wing at a right angle to the body and with the front wings far enough forward to just clear the hind wings. The front and hind wings of a butterfly, moth, or mayfly overlap at the base, with the front edge of the hind wing under the rear edge of the front wing, and should be so overlapped when spread. The front and hind wings of most other insects are not overlapped when spread.

For the beginner and those interested primarily in mounting a few large or showy insects for display, we recommend spreading the insect in an upside-down position and mounting it under glass; spreading is easier this way, and does not require a special spreading board. For the more advanced student, or anyone planning to specialize in insects that are normally spread, we recommend the use of a spreading board.

The steps in spreading a butterfly in an upside-down position are illustrated on p. 16. Butterflies and moths must be handled carefully (forceps preferred) to avoid rubbing scales off the wings. To spread a butterfly, grasp it by the thorax, ventral side up, and insert a pin through the thorax. Pin the insect on its back on a flat surface; if the wings are together above its back, spread them apart with forceps as the insect is lowered to the surface. Pin strips of paper over the wings on each side (A). Remove the lower pin on one side and, holding the strip fairly tight, raise the front wing. Do this with a pin, placing the pin behind a heavy vein near the front basal part of the wing; avoid pushing the pin through the wing because this leaves a hole. If the body tends to swivel, insert a pin alongside it at the base of the abdomen. When the wing is raised to the proper position (rear edge at a right angle to the body) insert a pin through the paper strip just in front of the front edge of the wing (B); pin the lower end of the strip down, anywhere behind the hind wing. Now do the same thing on the other side (C). Next raise one hind wing so that the notch at the side between the two wings is reduced, and pin the paper strip just behind the rear edge of the hind wing (D). Repeat the process on the other side (E). Next orient the antennae to a symmetrical position and hold them in place by pins placed alongside them (E). Now hold the body down with forceps at the pin through the body, and carefully remove this pin (F). If the legs project upward very far fasten them close to the body with a strip of paper across the entire specimen, at right angles to the body. Data on when and where the specimen was collected should be noted beside it, this information accompanying the specimen when it is later put into the collection.

The time required for a spread specimen to dry will vary with its size and with temperature and humidity. A large butterfly or moth that might take several days to dry at normal room conditions can be dried in an hour or two with heat — in an oven or under an electric light. To determine if the specimen is dry, touch the abdomen gently with a pin; if the body is stiff the specimen is dry, but if the abdomen is still flexible the specimen is not yet dry.

A specimen spread on a spreading board is spread the same way, except that the insect is pinned through the thorax from above and placed at the standard height on the pin. The pinned specimen is then placed on the board, the pin going into (perhaps through) the cork strip at the bottom of the groove, until the base of the wings is even with the upper surface of the top piece of the board. Next the wings are spread and fastened down and the antennae oriented to a symmetrical position. Do not remove the pin in the insect's body after the spreading.

Mounting on Slides. Small insects, particularly soft-bodied forms that shrivel when preserved dry, and various insect parts (genitalia, wings, mouth parts, etc.) are often mounted on slides for detailed study. Insects and parts that are thick or dark-colored are usually cleared (made translucent) before mounting. Then they are mounted on microscope slides in some type of mounting medium (like Canada balsam). Such mounting involves treatment of the specimen with various reagents. Consult technical books for an explanation of the process.

Insect wings can be mounted on slides (preferably 2x2 in., which can be projected) without any mounting medium. If the wings are not folded they can be broken off a dried specimen, placed on a 2 x 2 slide and oriented, another slide put on top, and the slides taped together. Such a slide is permanent, and can be made in a few minutes. A folded wing must be relaxed and unfolded before it is mounted. This is done by putting the wing in alcohol or a special relaxing solution. The flattened wings are allowed to dry before the other slide is added. The wings of butterflies and moths can be mounted this way, but cannot be projected unless the scales are bleached or removed; directions for doing this are given on p. 221.

Preservation in Envelopes. Use envelopes for the permanent preservation of slender and relatively fragile insects such as dragon-flies, damselflies, and crane flies. This method saves considerable space compared to mounting on pins, and the specimens are less apt to be broken (or if they are, the parts are not lost). The simplest type of envelope is a triangular one (see p. 9), labeled on the outside. If clear plastic envelopes are used, it is possible to study the specimens without removing them from the envelope. Labeling for specimens in plastic envelopes can be done on a white card (same size as the envelope) placed inside with the specimen.

Preservation in Fluids. Larvae, nymphs, and soft-bodied adults are usually preserved in fluids, since they shrivel when preserved dry. The best preservative is a 75-80 percent solution of ethyl alcohol. Alcohol is a killing agent for most insects but is unsatisfactory for killing larvae — it may distort or discolor them. Larvae should be killed by hot water or chemicals. A good killing solution for larvae is one containing 1 part of kerosene, 7-10 parts of 95 percent ethyl alcohol (less for very soft-bodied larvae), 2 parts of glacial acetic acid, and 1 part of dioxane. Isopropyl alcohol (rubbing alcohol) will serve if ethyl alcohol is not available.

Containers of specimens preserved in alcohol should be completely filled with alcohol and tightly stoppered to reduce or prevent evaporation. If a large number of specimens are killed in a small amount of alcohol, this alcohol should be replaced after a day or two. Rubber stoppers are better than cork ones. Periodically inspect containers of specimens in fluid and replace any evaporated fluid.

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