31 October 1995
Volume 3: no. 6
Cool winds have begun to blow and with them most of the insects have begun to disappear, though we still see the occasional butterfly and grasshopper during the warm part of the day. Many of you have already had opportunity to display your insect collections at county, area, state and regional fairs. The insect collections were all pretty good this fall and the quality keeps improving. If you had a collection or had a hand in helping to get one ready for display this fall I congratulate you and encourage you to keep up the good work. As you get your collections back home from the various fairs, it might be smart to `winterize' them. Check the collection for any `twirlers' which may have developed during movement. These are insects which have become loose on their pins and which tend to turn to one side or the other. A spot of glue on the underside of the insect's body will hold it in place. (Elmers works fine for this.) Make notes on which insects are ragged or improperly pinned and need to be replaced. Work to improve your collection by replacing these specimens within the next year. Many of the judges at the various fairs will write critique sheets giving pointers on ways to improve collections. Check your collection for scavengers and damage. Collections which have been sitting for a time will often have small piles of dust below pinned specimens which are infested with scavengers. Collect one of these small insects to be added to your collection, but replenish and increase the amount of protectant in your box. Moth crystals may need to be placed in more than one corner, especially if the box is not air tight. Vapona strips are also often used in insect collection boxes to protect against dermestid attack. Now is also a good time to clean kill jars and replenish supplies, or at least make lists of needed items for collection kits. A list of needed items, i.e. black light, head lantern, spreading board, might even make it onto a Christmas list. It is also important that any `left over' specimens which were collected during the year be worked up and cataloged. Now would also be a good time to begin a new insect project. We demonstrated `casting' insects in plastic during camp this year, now might be a good time to try this project, especially if you have some insects in alcohol handy. (The following discussion is taken in part from the Univ. of Tenn. Entomology 4-H Leader Guide, Pub. 1002).
Almost any insect can be embedded in plastic when care and practice are used. Beetles, most moths and butterflies, and immature insects are well suited for preservation in this medium. A great deal of practice, patience, and experience is needed to make top quality embedments. Several companies make and sell casting materials. Most craft stores either carry the casting plastic and catalyst or can order it. Choice of molds is also important. Tupperware type plastic molds are good and even plastic ice trays may be used for small insects.
- The process of embedding consists of pouring one layer of `catalyzed' plastic into a mold where it is allowed to harden. As the plastic hardens an insect is placed `feet up' in the center. Then another layer is poured on top and the casting is set aside to harden. Heat and/or sunlight will speed up the hardening process. note: plans should be made to pour more than one mold at a time to keep from wasting plastic. Once catalyst is added the plastic will harden within a matter of minutes. So a 2 phase mold will require 2 mixing sessions, etc.
- Freshly caught insects, the size of a bee or smaller, usually will work well for `first' embedments, but they often develop a white sheen around the body as a result of moisture or trapped air. Dried or partially dried beetles are probably the easiest specimens to begin with. (Don't start out with a prize beetle, practice some before attempting to embed it!)
- Butterflies and moths should be spread and dried before attempting embedment. If the insect's body can be flattened during the drying period it will help with the embedding process. (Practice with beat up specimens before going to the prize.) Air bubbles under the wings and around the body can often destroy to looks of the embedment.
- Moisture is easily removed from specimens using alcohol. Beetles or other insects, including immatures, which have been held in alcohol are ideal candidates for embedment. The `catalyzed' plastic will readily bond around the insect bodies cutting down on the air and moisture which will form the sheen around the specimens. There is some difficulty still with large insects which must be poured in 2 or more sessions, but this can be overcome by being patient and not hurrying the steps. The amount of catalyst can be varied slightly to allow bubbles to escape, but care and experience must be used to assure that the plastic will harden.
- Make sure that specimens to be embedded are ready before mixing in the catalyst. Always follow the label directions for adding catalyst. Stir in the catalyst thoroughly but slowly and methodically with a metal stirrer so as not to introduce air bubbles.
- It is best if the molds jell slowly allowing bubbles to escape, thus most often when the temperature is 70 degrees or higher the mold should not be set in the sunlight or in the presence of heat. (All work with plastic casting should be done in a well ventilated area!!)
- When several embedments are being made at the same time with one batch mixing of plastic, let the first layer harden, then position the insects and add a few drops of catalyzed plastic to each specimen. When this hardens enough to anchor the insect in place, pour the covering layer.
- Allow the casting to cure slowly, at least 24 hours, then remove it from the mold and immerse it in cold water for a few minutes. Remove sharp edges or irregular surfaces with fine grit sandpaper. Final polishing can be done using jewelers rouge.
The deadline for the `Bee Essay Contest' is close, if you are interested in writing an essay, contact with your 4-H Agent, quickly. They will either have or can get the rules and information from the entomology department. There are scholarships and other awards available.
Dr. Michael R. Williams
Entomology & Plant Pathology
Mississippi State, MS 39762-9775
phone - 601-325-2085
home - 601-323-5699
FAX - 601-325-8837