How to prepare voucher specimens of adult Odonata

The Michigan Odonata Survey requires that state and county records be supported by voucher specimens, and in general significant records of insects, plants, and many other taxa should always be documented and archived with a specimen. Please read this post for an explanation on the justification and value of collecting vouchers.

This post outlines how to prepare adult Odonata specimens, what data to collect, how to record it, and how to submit your records.

Some additional resources:



On the day you collect your specimen(s)

High quality specimens, with all their parts and colors preserved, are easy to achieve, but care must be taken right from the time your adult dragonfly or damselfly is collected. 

Immediately after collection, while you are in the field, you should take your dragonfly from your net; hold it by folding the wings over the back of the insect and holding them in a folded position.

Some larger species, such as this Spatterdock Darner (Rhionaeschna mutata),
can  nip a little bit. Don't be startled, they can't break the skin. The wings of
odonates, once completely dry after emergence, are very tough. They can
be held safely this way.
Place your insect, with the wings still folded over the back, into a glassine envelope, the kind used, for instance, in stamp collecting. They come in various sizes. Each individual insect should be placed in its own envelope; occasionally small damselflies can be put together, but it's best to avoid this.


Note a corner is torn off.
More on that below.

It's important to fold down the top of the envelope so the insect can't escape. Multiple envelopes can be placed in any sort of hard-sided box or container carried in your field pack. Here are a couple of examples:



If you collect in more than one location, you'll want to devise a way to segregate what was collected where. For each specific location, write down GPS coordinates. Be as precise as possible. These can be obtained from various cell phone apps or, even if done later, from Google Maps (see how here) or Google Earth (see how here). Decimal coordinates are preferable, and information is available on the linked pages. 

If at all possible, jot down other notes, such as habitat, number of individuals present, etc. This information can be included with your specimen and provide valuable insight for others in the future. Just take a look at the wealth of data that was jotted down on this specimen from 1929!

When you are finished collecting, your insects need to be killed in a way that is quick, safe, and preserves their colors. This is done by submerging the envelopes in a jar of acetone, available at any hardware store. Please work with acetone in a well-ventilated area. This should be done as soon as possible after collection. Once a dragonfly dies, decomposition and other processes occur that distort important features, and color fades. Poor quality specimens with compromised identifiable features, or those that may be contaminated with molds, etc. may not be suitable for use as a voucher specimen.

We use one or more wide-mouthed jars that are large enough to place the envelopes in without jamming them together. You can separate different collecting locations, or different sized envelopes. It is helpful to have a very small corner of each envelope snipped off so that they fill up with acetone without the insect floating out the top.

Insects typically die within a few seconds after being submerged in the acetone. It's best to check the orientation and reposition the adult's body position if necessary. It's best to straighten the abdomen, move the legs so they don't cover the secondary genitalia, position the wings if needed, and be sure the ode won't slip out the torn off corner (this can be an issue with damselflies).

Acetone not only preserves colors, it removes fats from the insect that are the source of decay. Large dragonflies should be ready to remove from the acetone in 24 hours. Small damselflies may take only 10 hours. You can't really tell when they are "done," so we just leave damsels in overnight and wait another half a day for dragons.

At that point, use some sort of flat-tipped tweezers or tongs to remove the envelopes. Hold them over the container for a few seconds to drain the acetone, then place the envelopes in a glass or ceramic holder to allow them to air-dry. Acetone will evaporate relatively quickly, but we typically let them dry for at least a day. Again, use a well-ventilated area.





Acetone will evaporate relatively quickly, but we typically let them dry for at least a day before transferring the specimens to clean, unsnipped glassine envelopes. The envelopes you used for collection and dunking can be re-used.

The acetone will eventually turn yellow from the fats. It should be discarded and replaced with fresh acetone.


Documentation

Proper documentation of your specimens is essential. Once your specimen is in a clean envelope, you should place a tag inside the envelope that identifies that specimen, and fold over the top of the envelope.  Your tag will contain, at a minimum, some sort of identification number (of your choosing) that will correspond with all the data that needs to accompany the specimen. We also put the Latin name on the tag. This presumes you know the identification of the insect. Some species may represent significant identification challenges. However, we discourage indiscriminate or unnecessary collecting simply in order to identify species. 
Collecting insect specimens has great scientific value. An improperly handled or preserved specimen, or one without sufficient data, is just killing an insect.

We keep a spreadsheet that matches the number on the tag in the specimen envelope with all the corresponding information: date, location, identification, notes, etc

Finally, store your specimens in a box that you can close and which is relatively air-tight. Carefully place the envelopes to that they won't be crushed, and insects or tags won't accidentally slide out. We also put a couple of silica gel packs in the box. 




Getting your vouchers to a curated collection

We submit our vouchers to the University of Michigan Museum of Zoology, which has one of the premier insect collections in the world. The Odonata collection is also one of the best and largest in the world, and formed the basis for the Michigan Odonata Survey. The collections are housed at the Research Museums Center in Ann Arbor. Erika Tucker is the insect collection manager. 


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