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COLLECTING INSECTS
Collecting Equipment
Trapping Equipment
Collecting Techniques
PRESERVING INSECTS
Equipment
Preservation
Becoming a serious collector
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Job opportunities
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Acknowledgements
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References
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APPENDIX
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COLLECTING INSECTS
Collecting net, Dip net, Beating tray, Aspirator, Camel-hair brushes, Forceps, Killing bottles, Glass vials, Field storage box, Paper data labels and pencil, Collecting bag, Suppliers
Collecting net - Figure 1The insect collecting net is the basic tool of the insect collector. The net should be light and the handle may be made from an aluminum pipe, a broom handle or a sturdy dowel stick. The length may vary between 50-120 cm. A metal opening or hoop, no less than 30 cm in diameter, can be made from heavy steel wire, about 5 mm in diameter. The net bag should be about 90 cm deep tapered at the bottom, and made from nylon mosquito netting which does not disintegrate or tear easily. Around the hoop the net should be reinforced with strong binding material. The ends should be left open so that the metal ring can be passed through the binding. One way to attach the ring to the handle is to use hose clamps. Another way of attaching a wire ring to a wooden handle is as follows (see Figure 2): The open ends of the ring are bent outwards, at right angles to the circle, and again inwards at right angles towards each other a few centimetres further along, i.e. a short distance from the ends of the wire. A groove is cut in each side of the handle, with a shallow hole at the end of each groove towards the centre of the handle. These grooves and holes will accommodate the wire ends of the ring and the wire should fit snugly into them. To keep them in place, a tight-fitting metal ferrule is slipped upwards on to the handle over the wires to hold them firmly in place.
The insect net can be used to collect individual specimens when they are in flight or at rest on flowers or shrubs (Figure 3). Once an insect is caught in the net, the handle is given a quick twist to fold the bag and prevent escape. The insect is then transferred into a suitable container or a killing jar. General collecting can be done by sweeping the net back and forth through foliage and grasses. Sweeping results in the collection of a mixture of insects which may be removed by hand, forceps or an aspirator. Another way of dealing with the sweep-net catch is to shake the contents of the net to the bottom and invert the net into a killing bottle. Insects can then be sorted later. This technique may result in the excessive collection of unwanted specimens.
Dip net - Figure 4The dip net is used to collect aquatic insects. It has a shorter bag and a fairly long handle. Some are designed with a flat side opposite the handle to allow the net to scrape along the bottom of a pool. Most aquatic insects are the immature stages of the insect life cycle. The nymphs of dragonflies (Odonata), mayflies (Ephemeroptera), stoneflies (Plecoptera), caddisflies (Trichoptera), mosquitos and midgets (Diptera) may be found in pools and streams. Some very interesting aquatic adult insects such as water scorpions, water-striders, backswimmers, giant water bugs (Heteroptera) and whirligig beetles (Coleoptera) may be found in the water or on the surface. The contents of the dip net can be emptied into a shallow white plastic tray of water and the required insects can then be sorted easily. Surplus insects should be returned to the habitat from which they were collected.
Beating tray - Figures 5, 6The object of beating is to capture crawling insects which do not fly readily. The beating tray can be made from strong white cloth, rectangular or square, about 100cm x 60cm, with pockets at the corners into which the ends of two diagonal bracing sticks are fitted. The tray is held beneath the branches of trees and shrubs and the branches beaten with a strong stick. The insects are dislodged and fall into the beating tray. The specimens are then collected by hand, forceps or aspirator. With the sticks removed, the beating tray can be rolled into a neat parcel for easy transport.
Aspirator - Figure 7The aspirator bottle is a device for collecting small delicate insects individually. It is used to collect insects directly from the ground, foliage, the net or from the beating tray. An aspirator bottle consists of a bottle (7cm x 2,5cm) fitted with a rubber stopper. Two holes are drilled through the stopper to take two pieces of hard plastic tubing, each about 7cm long and about 5mm in diameter. One piece of tubing is pushed through each hole in the stopper, with at least 2cm showing below and above the stopper. The end of one of the pieces, which will be inside the bottle when the stopper is inserted, should be covered with a piece of mosquito netting to prevent insects being sucked into the mouth of the collector. A rubber tube 30-45cm is attached to both plastic tubes on the outside of the stopper. To use the aspirator, air is drawn through the apparatus by sucking on the rubber tube with the mosquito netting. The insect is sucked into the chamber through the other tube which is pointed towards the insect.
Camel-hair brushesDelicate insects that are best stored or preserved in alcohol can be picked up on the tip of a fine brush moistened with alcohol and then transferred to a glass vial containing alcohol.
ForcepsThe best forceps are those with prongs that are rounded or come to a point and the inside surfaces are milled. The prongs should make contact at the tips only, so that an insect can be gripped firmly without slipping out. Soft stamp collector forceps are useful for soft bodied insects.
Killing bottles - Figure 8Once the insect has been captured, it should be killed quickly and in a way that leaves it relaxed. This is usually achieved by placing the specimen in a killing bottle moistened with a killing agent. The agent must be relatively harmless to humans e.g. ethyl acetate. Only one or two drops are needed to charge the jar with vapour sufficiently concentrated to effect rapid death. Excess ethyl acetate causes condensation on the inner walls of the jar which will wet and discolour specimens. Any wide-mouthed glass jar can be used with a simple modification. Cover the bottom of the jar with a thin layer of sawdust. A sheet of paper, cut to the shape of the jar, is placed on top of the sawdust, which is then covered with a mixture of plaster of paris and water to a depth of about 10mm. The plaster of paris is made by adding powdered plaster of paris to water, little by little, stirring continuously, until the mixture has the consistency of Relaxing box thick cream. It is then poured into the middle of the paper in the jar and allowed to spread out to the sides. The jar is then placed outside in the shade to allow the contents to dry completely. Bottles and jars are different sizes can be prepared in the same way. It is advisable to have at least three killing jars - one for grasshoppers which kick and dribble, one for moths which shed scales all over the jar, and the third for other insects. Never put delicate insects like butterflies with hard insects like beetles into the same jar.
Glass vialsA collecting kit should include several glass vials, preferably in a range of sizes, some clean and dry and others containing liquid preservatives. Soft-bodied insects and larvae are placed directly into preserving solutions. This kills the insect as well as preserving and storing it. The dry bottles are used for transporting live specimens for rearing or later study.
Field storage boxAnother important item of field equipment is a box or tin containing layers of soft tissue paper, cut size, that fit snugly into the corners of the box. When the first batch of insects is ready to be taken from the killing jar, the top layers are removed in order to start at the bottom of the box. The dead insects are emptied onto the bottom layer and a data label is placed with them. The rest of the tissue paper layers are then placed on top. The same procedure is followed with the second batch of insects; each batch must be separated from the previous one by a layer of tissue. Each layer must receive its own data label and specimens from separate localities should not be put together. The insects should be pinned before they dry out, but if that is not possible they could be placed in a relaxing box for a day or two. A relaxing box is a dampened airtight box with a drop of ethyl acetate to prevent fungal infection.
Paper data labels and pencilEach specimen must eventually be labeled with the information relating to its capture. This must be recorded at the time of capture and it is convenient to have some small paper labels ready (about 50 x 15 mm). The basic information required for every specimen should include the following: locality, date of capture and the name and initials of the collector. A grid reference would also be useful for more accurate location. The label information must be recorded in the field; never trust your memory when it comes to label data. Specimens from different localities and dates should always be kept separate from one another and labeled separately. It is often useful to have additional information, like host plant, found under rock, trapping methods etc.
Writing in the field is important and it is best to use a HB pencil for this. Ball-point type pens are usually not satisfactory.
Collecting bagA canvas bag with partitions for sorting items is useful, and should be slung from ones shoulder by means of a strap to leave the hands free. A bag slung on the back has the disadvantage that it must be taken off each time it is needed.