Techniques for Studying Tiger Beetles - Preparing Specimens and Curating Collections

All tiger beetle pecimens coming out of the field should be accompanied by temporary data labels with information on date, locality and method of collection, as well as the name(s) of any collector(s). This information should be kept with the specimens at all times, until permanent labels can be made for each specimen. This same information should also be recorded in your field notebook

As a rule it is always best to mount tiger beetle specimens as soon as possible after you have captured and killed them. Working with freshly-killed specimens will prevent damage from handling and pinning. It also provides you with an opportunity to arrange the appendages (antennae, wings and legs) in a neat and orderly manner.

It is not always possible to mount all of your specimens after each field trip. Therefore, it becomes important to know how to temporarily store your specimens until you have time to work on them at a later date.

Tiger beetle specimens can be temporarily stored in a refrigerator for up to a week. Obtain a plastic or glass container with a tight-sealing lid. Line the container with paper toweling, then put the specimens and a small green leaf inside.  Specimens can be indefinitely stored by placing them in a freezer instead of a refrigerator. When you store insects in a freezer it is important to use a container that seals very tightly or your specimens will become freezer burned (dried out). When you remove specimens from a freezer, allow time for the container to reach room temperature before removing the lid. This will prevent moisture from condensing on the specimens and causing damage.

Tiger beetles can also be temporarily preserved in alcohol with good results. At times the specimens become discolored with a yellowish or brownish stain caused by a grease that forms from insect body fluids which have dissolved in the alcohol. If you see your alcohol turning yellow, replenish it with a fresh supply immediately.

Once tiger beetles have dried, they are very fragile. For this reason, they should be mounted (pinned, pointed, or spread) when fresh.  They are pinned through the thorax (the middle section of the body). A good rule of thumb is to pin the tiger beetle slightly to the right of the midline, near the front of the elytra (shoulder region).  The height at which specimens are pinned should be uniform, with about one-third of the pin exposed above the upper surface of the insect specimen . Also, the insect should be horizontal on the pin when viewed from both the front and the side.

As soon as the specimen is pinned, you must decide if you are going to spread the wings or neatly arrange the legs and antennae. You can use a large pinning board (made of cork or styrofoam) to hold the beetles in place while you arrange the legs or antennae. Use an insect pin to move the legs or antennae into the position you want; if the appendage will not stay where you want it, push the pin into the foam and leave it in place until the insect dries. While legs and antennae that are arranged so they stick out from the body looks natural, these delicate appendages are easily broken. For this reason many collectors prefer to crisscross the legs under the body and direct the antennae rearwards over the body.

Insect labels should be as small as possible, but must still be legible. All necessary information should be printed on high quality card stock using a fine-point pen and permanent ink.

If you need hundreds or even thousands of locality, bionomics or determination labels, then you probably won't want to hand print each and every one. Instead you can type out the information with a typewriter (or computer word- processor!) and then have the typed labels reduced on a copy machine.  There is even a special software program for label printing (EntoPrint link) - type the label onec and it will print as many copies as you desire.

If you do a lot of collecting you'll need a lot of locality labels. One helpful trick is to prepare "fill in the blank" labels for places you visit frequently. Such a label might look like this:

MICHIGAN: Ingham Co. 3miSW Lansing Grand River Park                            19

Every time specimens are collected at Grand River Park its a simple matter to fill in the appropriate date.

A locality label (see below) should accompany each beetle specimen, whether pinned, pointed, or in alcohol. The label should contain the following information: location (state, county and nearest town or other permanent landmark), date(s) of collection, and the name of collector(s). When writing the date on a label, use one of the two following formats: 11 SEPT 1993 or 11-ix-1993. If you use 11-9-93 for the date, other collectors will not be sure if you meant November 9th or September 11th. If specimens were collected in an trap that is checked weekly, the date is best stated as a range of dates; for example, 11/18-ix-1993 or 11-18 SEPT 1993. The locality label goes on the pin directly beneath the specimen.

An optional second label, known as the bionomics or ecology label, is used to record additional detailed information on host, habitat, altitude, collecting method (including trap type, etc.) bait preferences, and time of collection to further describe the life history of the collected species; this greatly increases the specimen's value to entomologists. The abbreviation "EX" is used in place of "taken from" on bionomics labels. This label also goes on the pin, beneath the locality label.

Immature tiger beetles (larvae) are best preserved in 75% ethyl alcohol.  However, its not simply a matter of placing the specimens in a vial containing alcohol.  You must take an extra step to prevent the black discoloration that occurs when immature insects (especially larvae) are improperly preserved. This discoloration is caused by bacteria that are not killed quickly by the alcohol and that eventually turn the specimen in a black, mushy blob. These bacteria must be killed by a process known as "fixation".  To "fix" a specimen before preserving it in alcohol, place it in very hot (near-boiling, about 180o F.) water. Heat some water until it begins to boil, then turn off the heat. Water which is too hot, or which is boiling vigorously, may cause specimens to burst. When the process is complete, remove the specimens from the water, place them on absorbent paper to soak up excess moisture, and then place them in alcohol.

A collection of pinned insects must be properly stored in order to protect it from damage (jarring and vibration), dust, light, dampness, and infestations of carpet beetles and other museum pests. Proper storage and care of your collection will ensure that it lasts for a long, long time.

Always keep your specimens firmly pinned to the bottom of a tightly covered box. At first you may want to use Schmidt boxes, but as your collection grows you may want to switch to museum drawers and unit trays.

FOR MORE DETAILED INFORMATION ON PINNING AND CURATING SPECIMENS, REFER TO THE BEGINNER'S GUIDE TO OBSERVING AND COLLECTING INSECTS AVAILABLE AT THE MINIBEAST MERCHANDISE MALL

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This educational resource was prepared by the Young Entomologists Society, 6907 West Grand River Ave., Lansing MI 48906-9131, phone/fax 517-886-0630, e-mail YESbugs@aol.com.  Support minibeast youth education - join Y.E.S. today!