Collecting Equipment and How to Use It

The minimum equipment necessary to collect insects consists of your hands and a container for the insects collected. Certain tools are very helpful, nonetheless. For general collecting they include a net, killing jars, vials of preservative, envelopes, and small boxes; other tools are useful in some types of collecting. A pair of forceps is excellent for handling insects, as is a hand lens for examining them. Many of these items can be carried in a shoulder bag; the forceps and hand lens can be carried on a string around your neck.

The Net. A net for general collecting should be light and strong and have a fairly open mesh so that it can be swung easily and an insect can be seen through it. The size may depend on your personal preference, but most nets have a handle 2 to 3 ft. long and a rim about 1 ft. in diameter; the bag should be about twice as long as the diameter of the rim, and rounded at the bottom. Marquisette, scrim, bobbinet, and bolting cloth are good materials for the bag, which should have a heavier material, such as muslin, around the rim. A fine-mesh bolting cloth is probably the best material for the bag of a net that will be used primarily for sweeping.

Insect nets can be purchased from a supply house (prices ranging upward from a few dollars) or they can be homemade; homemade nets cost considerably less. An insect net can be made with a broom handle or similar stick, a wire for the rim, and a cloth bag, as shown in the illustration on the next page. If you prefer a net that can be taken apart and carried inconspicuously, use the frame of a fish-landing net, which you can buy from a sporting-goods store.

An insect net can be used in 2 general ways: you may look for an insect and swing at it or you may simply swing the net through vegetation. The first method requires a certain amount of speed and skill, especially for active or fast-flying insects. The second method, usually called "sweeping," can yield a considerable quantity and variety of small insects.

Insects caught in a net can be removed in various ways. Take care to prevent their escaping before you take them out of the net. Remove them with as little resultant damage as possible and — in the case of insects that bite or sting — without injury to yourself. You can keep an active insect from escaping by quickly turning the net handle to fold the bag over the rim.

Most insects can be removed from a net by grasping them through the net with the fingers. Small or fragile insects, easily damaged by this method, can be removed in these ways: (1) by inserting a box or bottle into the net and getting the insect directly into this container; (2) by working the insect into a fold of the net and placing this fold into a killing jar to stun the insect; or (3) by removing the insect with an aspirator (see p. 9). The first method is the one used by many collectors to remove butterflies or moths

The homemade insect net. Cut grooves on opposite sides of one end of handle, as shown in A, 1 to about 2 in. from end and the other to about 3 in. from end; drill a hole about halfway through handle at end of each groove. Bend wire for rim (about No. 8 gauge) as shown in B, fit into holes and grooves, and fasten it there with fine wire or heavy cord (C). Cut material for bag as shown in D and sew. Completed bag, with muslin around rim, is shown in E.

The homemade insect net. Cut grooves on opposite sides of one end of handle, as shown in A, 1 to about 2 in. from end and the other to about 3 in. from end; drill a hole about halfway through handle at end of each groove. Bend wire for rim (about No. 8 gauge) as shown in B, fit into holes and grooves, and fasten it there with fine wire or heavy cord (C). Cut material for bag as shown in D and sew. Completed bag, with muslin around rim, is shown in E.

from a net, since direct handling of the specimen often causes some of the scales to be rubbed off. If a butterfly or moth is grasped by the fingers through the net, grasp it by the body not the wings, and stun it by pinching the thorax before putting it into a killing jar (to reduce fluttering and wing damage in the jar).

Many beginners may be reluctant to grasp an insect for fear that it might bite or sting; such is much less likely than most people believe. An insect that bites does so by moving its jaws sideways and pinching or by piercing with the beak. Very few pinching insects are capable of causing pain or breaking the skin, and those that can are generally very large insects. Most biting insects are unable to bite if grasped firmly by the sides of the body.

An insect that stings does so with a structure at the posterior end of the body — usually quite readily. The only stinging insects are the bees, wasps, and some of the ants, and females alone can sting. Many flies and a few other insects strongly resemble bees or wasps but are quite harmless. If an insect in a net is one that might sting, remove it from the net in one of three ways: (1) put a fold of the net containing the insect into a killing jar until the insect is stunned (or pour an anesthetic such as chloroform over the fold of the net to stun the insect); (2) grasp the insect through the net with forceps and remove it; or (3) work the insect into a fold of the net, stun it by pinching the thorax, and then remove it. The third method is the simplest and quickest.

Insects caught by sweeping can be removed by shaking them to the bottom of the net and stunning them by the first method described above.

Killing Jars. Insects can be studied alive with considerable interest and profit, but it is well to kill and preserve a few. The characters that differentiate insects can be studied best in preserved specimens, and insect collections can be both attractive and instructive.

Killing jars are of various sizes and shapes, depending on the use they will receive. It is advisable to have 2 or more jars in the field, for insects of different types. Wide-mouthed jars are preferable to narrow-mouthed ones, and glass jars should be reinforced with tape to reduce the hazards of breakage. Several materials can be used as killing agents, but the best are probably ethyl acetate and cyanide. Ethyl acetate is a much safer material to use than cyanide, but does not kill as quickly, and jars made with it must be recharged frequently; specimens killed by ethyl acetate are usually more relaxed than those killed by cyanide, and less likely to be discolored. Cyanide jars last much longer, and are quite safe to use if certain precautions are observed. Most collectors prefer to use killing jars made with cyanide.

Ethyl acetate (an ingredient of nail polish) is a clear liquid, and its fumes act as the killing agent. Jars made with it must contain something absorptive. Cotton or cloth can be used as the absorbent material, but plaster of paris is better. Pour a mixture of plaster of paris and water into the jar and allow it to set and dry; then place a few eyedroppers of the acetate on the plaster (which absorbs it), and the bottle is ready for use. Take care not to put in too much acetate, because wet insects make poor specimens. Add more ethyl acetate every few days.

Cyanide jars can be made with calcium, sodium, or potassium cyanide. Calcium cyanide is a dark gray powder often used as a fumigant and ordinarily is obtained from a store that sells insecticides. Sodium cyanide comes in the form of balls about an inch in diameter, which must be crushed before use in a killing jar; it is obtained from a company dealing in insecticides or chemicals.

Potassium cyanide (which looks like sugar) is usually available at a drugstore. The toxic agent in a cyanide jar is hydrogen cyanide, an extremely poisonous gas given off by the action of moisture on the cyanide. Calcium cyanide releases this gas very rapidly, and is perhaps the most dangerous type of cyanide to use; jars made with it ordinarily last only a month or two. Sodium and potassium cyanides give off the gas less rapidly and are less dangerous to use; jars made with them may last a year or more. Cyanide jars are easy to make but we recommend that the beginner not attempt to make his own. He can ask someone experienced in handling cyanide to make them for him or else buy them from a supply house.

The chief hazard in the use of cyanide jars is not so much the gas given off (which is toxic if inhaled in quantity) as the possibility of a broken jar and a cut hand. This hazard can be greatly reduced by covering the bottom part of the jar with adhesive, masking, or electric tape. All killing jars should be so taped, and all should be conspicuously labeled POISON.

Other materials that can be used in a killing jar are carbon tetrachloride and chloroform. Carbon tetrachloride is the easier to obtain but is more dangerous. A killing jar made with either of these materials (which are liquids) is made in the same way as an ethyl acetate jar, and must be recharged frequently.

The efficiency of a killing jar depends to a large extent on how it is used. Never leave it open any longer than necessary. The hazard of an open jar, even one made with cyanide, is not very great, but the escaping gas reduces the strength of the jar. Keep the inside of the jar dry. Moisture from the insects or from the plaster sometimes condenses on the sides, particularly if the jar is exposed to bright sunlight. Moisture can be reduced by keeping a few pieces of cleansing tissue in the jar. When butterflies or moths are put into a jar, many of their scales come off and remain there; other insects put into this jar will become covered with the scales and look dusty. It is advisable to have a special jar for butterflies and moths and put other insects into different jars. All killing jars should be wiped out occasionally.

The time required for a killing jar to kill an insect depends on both the jar and the insect, and may vary considerably. Insects can be left in an ethyl acetate jar for long periods without damage, but if left too long in a cyanide jar they may become discolored. Remove insects from a jar within an hour or two after they are killed.

Specimens removed from a killing jar in the field may be stored temporarily in small boxes or envelopes; the boxes should contain some pieces of cleansing tissue. Letter envelopes, or triangular ones (see illus. opp.), are better for insects with small bodies and large wings (butterflies, moths, dragonflies, etc.). Place the specimen in the envelope with the wings together above the body and write collecting data on the outside of the envelope.

A triangular paper envelope, made by folding a piece of paper as shown in A, B, and C to form the completed envelope (D).

Beating. Many insects that occur on plants "play dead" and drop off the plant when it is jarred. You can collect such insects by placing a net or sheet under the plant and beating the plant with a stick. An insect net does not provide much collecting area. A better device is a sheet of white cloth about a yard square, held spread out by two slender pieces of wood along the diagonals of the cloth.

Sifters. Insects occurring m leaf litter or debris are most easily collected by some kind of sifting device. The simplest procedure is to shake a handful of the debris onto a sheet or cloth. Small animals present will be detected by their movement and can be picked up with forceps, an aspirator, or a wet brush. A more efficient method is to use a Berlese funnel, a large funnel with a circular piece of screen or hardware cloth in it. The material to be sifted is placed in the funnel on the screen, the funnel is held upright with a ringstand or other support, and a container (usually of alcohol) is placed below the funnel. As the material dries (this can be hastened by a light bulb over the material) the insects move downward, and eventually go into the container below the funnel. Generally it takes a few hours to get most of the insects out of the material by this method.

Aspirator. An aspirator is a device with which insects are sucked into a vial or other container. This container has intake and mouthpiece tubes entering it; the intake tube is usually a piece of }4-in. glass tubing about 6 in. long, and the mouthpiece tube is }4-in. glass tubing through the cork plus 1>2 to 2 ft. of rubber tubing, with a piece of cloth over the inner end to prevent insects from being sucked into the mouth. Place the end of the intake tube close to the insect and suck through the mouthpiece. An aspirator is useful for collecting small, not too active insects, either from an insect net, a plant, or another situation. The insects so collected may be kept alive or transferred to a killing jar.

Traps. Insect traps can be constructed in various ways, and the attractant used will determine the types of insects likely to be caught. The attractant may be artificial light, decaying meat or fruit, or other things. The traps are constructed so that once the insects get in they cannot get out. Some traps (such as those with light as the attractant) may be constructed to direct the caught insects eventually into a container of alcohol or a killing jar; others (such as traps baited with decaying materials) may be constructed to direct the insects into a special chamber and not into the bait.

Insects attracted to lights or baits may often be collected by hand or with a net, without use of a trap. Insects attracted to a light, for example, can be collected directly into a killing jar or other container when they alight on some surface nearby (a light-colored wall or sheet). Thus you can collect only those specimens in which you are particularly interested.

Aquatic Collecting Equipment. Many aquatic insects can be collected by hand or with forceps from pbjects in the water; more can be collected with a net or other device. An aquatic net should be much sturdier than an aerial net, with a bag no deeper than the diameter of the rim. Kitchen strainers 4 to 6 in. in diameter make good dip nets.

If a dip net or strainer comes up full of mud and debris, the insects taken may be difficult to see unless they move. To locate them, dump the net contents into a white-bottomed pan of water. Insects are easily seen against this white background, and can be removed by hand, forceps, or eyedropper. Small free-swimming forms like mosquito larvae are best collected with a long-handled white enameled dipper, in which the insects similarly show up well. Remove them with an eyedropper.

Other Equipment and Methods. Many insects can be collected directly into a killing jar or other container, without the use of a net. This is the simplest way to collect insects that alight on a flat surface and do not fly too readily, and many insects on flowers. Various types of buildings often serve as insect traps; insects fly in and alight on the walls or ceiling and remain there, or they alight on windows — from which they can be collected directly into a jar.

A heavy knife is useful for cutting into logs or branches, opening galls, prying up bark, or digging into places that may harbor insects. Keep at hand a notebook and pencil for taking notes, and make triangular paper envelopes from the notebook pages.

Collecting some kinds of insects requires special equipment not mentioned above. An ingenious collector should be able to devise equipment and procedures for collecting such insects.

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