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Collecting Insectsby Anne Wallingford
Insects! Let's face it, most adults dislike "bugs." But have you ever watched a young child who is fascinated by a bug? Disliking "bugs" is a learned trait. Since the best way to overcome a dislike for a subject is to study it, we might discover that collecting and preserving insects becomes a simple way to overcome our dislike.
Because insects are found everywherein fresh water, on plants, under rocks, in the soil, and even in the housethere should be no problem in starting a collection. However, only insects that are plentiful in an area should be collected. Insects that are helpful to the environment should be observed but not collected. Also, be sure to check your local laws as it is illegal in most places to collect insects from city parks, forests, and nature preserves. Collecting insects may be a good biology lesson but it must be done without endangering the environment.
Some insects are scavengers that survive on spoiled foodstuffs, animal carcasses, or other waste products. Use caution if collecting these types of insects because they can transmit diseases. Actually, it's a good idea to wear protective clothing whenever collecting insects: long-sleeved shirts and pants, thin gloves, face masks, and a hat.
Collecting equipment is pretty basic. You need an insect net, a few vials or assorted small containers with lids, and a flashlight (for nighttime excursions.) A canvas knapsack is helpful for carrying equipment and collected specimens.
Making a Killing Jar
Unless specimens are going to be immediately released, you will need an assortment of killing jars in different sizes because large, hard-bodied insects need to be kept separate from smaller soft-bodied insects. With a killing jar, chemical fumes kill the insect. Glass jars, such as baby food jars, mayonnaise jars, and canning jars, all work well. Do not use plastic containers because the chemicals used in the killing jars will soften the plastic. If your glass jar is not shatterproof, cover the outside completely with clear tape. This will prevent the jar from shattering if you should drop it.
To make a killing jar, use cardboard, blotter paper, or several thicknesses of filter paper, to cut a circle slightly larger than the jar's inner diameter. This circle will prevent chemicals from discoloring your insect specimens.
Next, place an inch of absorbent material such as a shredded newspaper, clay kitty litter, or cotton gauze, in the bottom of the jar. Pour a small amount of nonflammable spot remover or water-based fingernail polish remover (ethyl acetate) onto the absorbent material. Wet the material but do not soak it.
Then press the circle firmly into place over the moistened material, bending the circle slightly if necessary, but be sure the circle fits tightly. Put a lid on the jar and label the jar POISON. Always have the number of the Poison Control Center handy when dealing with any poisonous substances. The Center has the right information and updated call center software to deal with any poison emergency.
To make a longer lasting killing jar, start the same way, by cutting out a circle. But instead of using an absorbent material, mix a thick paste of plaster of Paris in the bottom of the jar. Let the mixture set for at least 48 hours, or until all the moisture is evaporated. Then pour a half-inch of nonflammable spot remover or water-based nail polish remover onto the plaster. Cover the jar tightly. After two days, pour off any excess fluid and cover the plaster with the circle. Put a lid on the jar and label the jar POISON. A plaster of Paris killing jar lasts for about a year.
Pinching the thorax of large butterflies or moths for 20-30 seconds before placing them in a killing jar will stun the insect and stop it from fluttering inside the jar. Remove these insects from the killing jar promptly so that their wings don't become soaked.
Insects can also be killed by freezing them. Place the insect in a small vial or jar and put the container in the freezer overnight. (Don't use plastic bags.) The frozen insect has to be thawed overnight before mounting.
Making a Relaxing Jar
Insects become stiff and brittle when left in a killing jar or freezer for an extended length of time. When this happens, the body must be relaxed before it can be mounted.
Once again, use cardboard, blotter paper, or filters to cut a disk slight larger than a clean glass jar's inside diameter. Place an absorbent material in the bottom of the jar. Sprinkle the absorbent material with water and a few drops of laundry bleach. (The bleach prevents the growth of mold.) Cover the absorbent with the snugly with the circle. Label the jar POISON.
Use small forceps or tweezers to gently remove the insect from the killing jar and place the insect into the relaxing jar. Close the lid tightly and set the jar aside, out of direct sunlight.
Check the jar after two days. If the insect is still stiff, leave it in the jar for another day or two. As soon as the insect's body is flexible, it is ready to be mounted. Be sure to check the jar daily! If left in the relaxing jar too long, the insect will decompose.
Making an Aspirator
An aspirator is a suction device used for collecting insects that are too small to be caught with your hand or with a net. To make an aspirator, you need a small vial or test tube, a two-hole stopper that fits the container tightly, a small length of flexible tubing, and two 4"-6" lengths of rigid tubing. (In a pinch, bendable straws can be used.)
Bend one length of rigid tubing into a 30º-45º angle. Bend the second length of rigid tubing to a 90º angle. After inserting the bent tubing through the stopper, cover the longer leg of the 90º tube with a small bit of cheesecloth or wire mesh. The covering can be held in place with glue, a rubber band, or anything else that will hold the screen in place. (The screen stops you from accidentally inhaling an insect.)
Attach the flexible tubing to the bent tube.
To use the aspirator, hold the slightly angled tube next to a small insect. Put the end of the flexible tubing into your mouth and suck hard. The force of the suction will draw the insect into the container. (Don't use this for ants; ants release a nasty tasting formic acid.)
Making a Light Trap
If you've ever stood near an outdoors light after dark, you know that light attracts many kinds of insects. But did you know that different insects are attracted to different types of light? Some insects, like moths, will be drawn to a standard white light bulb. But even more insects are attracted by ultraviolet, or black light.
To make a light trap you obviously need a light. A "trouble light" fixture, available at most hardware stores, works fine. You also need a 100-watt bulb, a funnel, and a wide mouth container such as a clean, empty juice can. Hang the light outdoors, about 4 ft. off the ground. (Be sure there is a nearby outlet.) If you hope to catch larger winged insects, cut the stem off the funnel. Hang the funnel from the trouble light.
Place 2" of crumpled newspaper in the bottom of the collecting can, and sprinkle the newspaper with either nonflammable spot remover or water-based nail polish remover. Secure the bottom edge of the funnel tightly to the collecting can. Turn on the light at dusk and shut it off at bedtime. Be sure to check the light trap daily. This can also be done using an ultraviolet, or black light. If you use an ultraviolet light, do not look directly at the light. Ultraviolet light can hurt human eyes. Caution: Do not operate the lamp in the rain or on wet ground.
Making a Pitfall Trap
Pitfall traps are useful for catching ground beetles and other insects that live on or in the soil. Bury a can in the soil until the rim of the can is level with the ground. Use small pieces of spoiled fruit, vegetables, or meat as bait. Cover the trap with a small board placed on top of stones; this protects the trap yet lets insects crawl into it. Once an insect falls into the can, it can't climb the walls to escape. Remember to remove any trapped insects each morning.
Hard-bodied insects have an outer exoskeleton with their soft parts on the inside. These insects will keep for decades after drying. Although some will fade, many will keep their original color.
However, soft-bodied insects such as aphids, lice, mayflies, and termites, as well as immature insects such as caterpillars, and wasp and beetle larvae, have to be preserved in alcohol solutions. You can use either a 70% ethyl or isopropyl alcohol solution; denatured solutions, available from your local pharmacy, will work fine.
Because specimens will often change color and shrivel when kept in an alcohol solution, insects need to be dipped in boiling water for 30 seconds before being transferred to the alcohol jar. Another option is to kill the insects in a special fixing solution known as a K.A.A. solution. To make a K.A.A. solution, mix one part of kerosene, two parts of white vinegar, and ten parts of 95% denatured alcohol in a glass container. For better results, substitute glacial acetic acid, available at photo supply stores, for the vinegar. You can also buy fixing solutions from many science catalog dealers.
It's easier to study soft-bodied specimens that have been dipped in a K.A.A. solution because the specimens uncurl and swell up. Specimens shouldn't be left too long in a K.A.A. solution, though, or they will burst. Small insects need about 30 min. and larger insects, like caterpillars, need 2-3 hours. After the insect has been fixed in the solution it should be transferred to a vial or other small container with a 70% alcohol solution. The container should then be sealed tightly with a stopper. Force an insect pin through the stopper, then withdraw the pin slowly. This "burping" releases air that has been trapped air in the vial. For larger specimens, replace the original alcohol in a day or two, then reseal and re-burp the container.
Many people who display insect collections use a Riker mount. A Riker mount is a specially designed insect display box. A Riker display box is basically a sturdy frame box, lined with cotton, and covered with a clear glass top.
You can make a temporary display box by lining a cardboard box with either foam material, corkboard, cardboard, or a thin layer of absorbent cotton. Carefully cut away the flat portion of the box's lid, leaving a slight inner border around the edge. Glue clear acetate to the inside of the lid. Be sure to use a large enough box so that the mounted insect isn't squashed when the lid is placed on the box. The lid of the box will have to fit tightly.
Pinning and Mounting Insects
Insects with large wings, such as moths and dragonflies, need special handling. To begin, cut several thin strips of paper 1/4" wide and 8-10" long. After the insect has been relaxed, pick it up and carefully push a pin through the middle of its thorax. Use the pinning block to properly align the insect, being careful not to damage the delicate wings. Remove the pinned insect from the pinning block and push the pin into the middle strip of the spreading board until the base of the wings (where the wings attach to the body) is even with the spreading board. Working on one side of the insect at a time, slip a paper strip between the wings. Use the strip to force the wings down until they are level with the spreading board. Pin down the paper strips. Do not put pins in the wings! Slip the point of another insect pin through the front edge of a forewing, to where the wing's most noticeable vein attaches to the thorax. Loosen one end of the paper strip and bring the forewing down until it is level with the spreading board. Fasten the wing into position with a paper strip. Do the same with the hind wing. Repeat until all the insect's wings have been positioned properly. The rear edge of the two forewings should be in a perfectly straight line. The rear edge of the hind wings should be angled slightly away from the insect's body.
If the abdomen is drooping, prop it up with pins so it dries in a natural position. The abdomens of large-bodied specimens have to be cut open on the underside and the contents removed with a cotton swab. The now-empty cavity should be stuffed with cotton so that it looks natural from above. (If this isn't done, the natural material inside the abdomen will decay and ruin the specimen.)
Use pins on either side of the antennae to hold them in position.
The specimen will have to dry for several days before the pins can be removed.
Labeling Insect Specimens
Unless properly labeled, an insect collection has little value. Each specimen has at least two labels placed on the pin underneath the specimen. The 1" x 3" labels should be parallel to the insect's body, not crosswise. If you have a pointed specimen, the labels should be parallel to the length of the insect. The insect's head should be on the left, and the labels read from left to right.
The top label identifies the county and state where the specimen was collected, the collection date, and the name of the collector. The lower label gives the insect's common (order) name. Sometimes a third label is placed beneath these two labels; this third label identifies the host plant, habitat, or other pertinent information.
Once your specimens have been pinned, mounted, and labeled, the specimens can be placed in your display boxes. If you have a large display box, group the insects in sections, by order. The specimens should be lined up in neat rows. A large label should be centered below each group.
To protect your collection from small beetles and their larvae, glue a small container inside the lower corner of your display box and put a tablespoon of moth crystals inside the container. Leave the crystals in the box for about a week, then remove them. Repeat this process every 3-6 months.
For more information on collecting and displaying insects, contact your area's County Extension Agent or your local 4-H office. Special thanks go to the Cooperative Extension Service, Institute of Agriculture and Natural Resources, University of Nebraska, and the 4-H Society, for providing research material for this article.
© 2004 Anne Wallingford. All rights reserved.
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Tuesday, October 20, 2009 (rev. 05/13/11, 02/10/12)