MadSci Network: Zoology

Re: How do you preserve insects well?

Date: Fri Oct 6 21:12:33 2000
Posted By: John Carlson, Medical student, MD/PhD (parasitology) , Tulane University, School of Medicine
Area of science: Zoology
ID: 968887874.Zo

Dear Ericka,

Thank you for your question on preserving insects. The study of insects is called entomology, and the people who study insects are called entomologists. Entomologists have developed ways to preserve insects to maintain the specimen's value for scientific study, as well as ways to display insects for their beauty. I will briefly describe the main methods of preserving insects, and then also give you references that you can use to start collecting insects on your own.

The most traditional method of preserving and displaying insects is with the use of special pins. The entomology pins come in different widths to be used on different sized insects. (The bigger the insect, the bigger the pin can be.) In general, entomologists insert the needle through the right side of the insect's upper abdomen. This pinned insect is then placed inside a collecting box (which I will describe below) or display case, with the tip of the pin embedded in cork board or Styrofoam. Beetles, grasshoppers and wasps can be easily pinned. The pins can be easily removed from the box and traded with fellow entomologists. These are much cooler than baseball cards!

Spreading is used for insects with large wings. The technique is the same as pinning, but care is taken to fix the wings in a good position. Spreading is done with the aid of a spreading board. (Spreading boards are a common possession of insect collectors, and can be purchased from any biological supply company.) The insect in pinned in the middle of the spreading board soon after it is killed, and the wings are held to the sides of the board with strips of paper for several days. After several days, the strips of paper are removed from the wings, which will have become hardened in place. Butterflies, moths, dragonflies, and even grasshoppers and beetles can be spread in order to better display their wings. My best friend is great at spreading insects. He is patient with placing the wings in just the right position before securing them in place, and then lets them harder for a week before carefully removing the insect from the pinning board. For my birthday he gave me a pretty Rosey Maple Moth from his collection which had been spread using a spreading board.

While there are special ways of pinning small insects using complicated, tiny pins, many entomologists prefer to point any insect that would break if a normal sized pin was used. To point an insect, first you must cut out a small triangle of stiff paper. A pin is passed through the center of the triangle, and the insect is glued onto the longest tip of the small triangle. In this way, the paper serves as a bridge between the insect and the pin, which is placed in collecting boxes with regularly pinned insects. One great tip is to use clear nail polish instead of glue for your best specimens. Small beetles and flies are often pointed. I have always liked working with small flies. It takes practice to be able to point an insect without getting glue or nail polish all over the fly's wings and legs. Because many entomologists get irritated with pointing such small insects, I have been able to trade some of my pointed flies to others for really interesting insects that they've pinned. (I aquired an amazing Tiger Beetle through just such a trade.)

For very small insects, slides are the best option for preserving them. The specimen is placed on the glass slide, and then a drop of glue is placed over it. A glass cover slip is then put on over the insect and glue, and allowed to dry. Some insects are best seen if they are prepared with special chemicals first to make it easier to see through them. Fleas, lice, and other tiny insects can be preserved on slides. Medical entomologists tend to be the ones that have insects preserved on slides. Because slides are difficult to keep in a collecting box, other entomologists don't tend to carry them around. Because so few entomologists have insects preserved on slides, you can look really cool when you show off your slides to friends.

For insects that would shrivel up if allowed to dry, alcohol is used to preserve them. Usually 70% ethanol is the alcohol used, but other alcohols will work also. The insect can be dropped straight into the water-tight vial with alcohol. Because this method is so easy, some entomologists will even use alcohol to preserve insects that would normally be pinned or pointed. Alcohol is used to preserve soft bodied insects such as termites, caterpillars, and grubs. Termites are among the most interesting organisms ever. (That is almost a scientific fact.) One of the most impressive collections I've seen is owned by the Audubon Institute down here in New Orleans. They caught thousands and thousands of termites as they swarmed one night in the French Quarter, and then dunked the lot of them in a giant container of a liquid preservative, which is probably alcohol.

Mounting is an easy way to display your beautiful and interesting insects that doesn't use pins. Mounting often uses a thick frame filled with cotton. Your insect can be softly squished between the front glass of the frame, and the cotton backing. The previously mentioned techniques are preferred if the insects are being preserved for scientific study because they can be easily moved around to be examined from all directions. However, mounting is a great way to show off your collection that takes up less time, and can be hung up on the wall. They also make great presents to your friends and family. Who wouldn't love to get a butterfly or dragon fly to hang on the wall?

It is always a good idea to label your insects. The collection label should include where the insect was caught, the date it was caught, and the name of the collector. Other information, such as the time of day, weather condition, and habitat can also be added to the label. A second identification label can also be added which gives the name of the insect and the name of the person that identified it.

Labeling helps scientists remember when and where they obtained the insects. This allows them, and other scientists, to try to catch more of the same insect in the future, or to study the movement of insect populations over time.

Collection boxes
Collection boxes are simple, study boxes with a Styrofoam bottom in which to place the pinned specimens. Moth balls or other preservatives can be added to the box to prevent other insects from coming in and eating your collection. The boxes are usually equipped with lid latches to protect your specimens when you transport them. Boxes can either be built at home, or purchased.

Collecting insects is a fun way to learn about the world around you. I recommend to you the Peterson Field guide for Insects by Donald Borror and Richard White. This is a great book for identifying insects, and also has more information on collecting and preserving insects. They also include some diagrams to help you understand the pinning techniques a little better.

Bioquip is a company that specializes in entomology products. You can buy spreading boards, collecting boxes, vials, pins, and many other things from them, as well as many other books to help you get started collecting insects.

If you have any more questions about entomology, please feel free to ask myself, or any other entomologist that you can find. (Entomologists are not only the smartest scientists around, but they are also the friendliest!)

Good luck!

John Carlson MAD Entomologist

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