Odonate collections form the raw material that has informed us about them over the last few centuries. This field guide could not have been written without a sizable collection for reference. We are still learning about the occurrence of most species, and voucher specimens are still essential to document distribution, even in this era of superb photographs and knowledgeable field observers. In addition, geographic variation cannot be understood without series of specimens from throughout the range of a species. Also, there are still some questions about species limits that can be settled only by researchers examining series of specimens. Independent of the scientific value of specimens is the heuristic value of handling them. Learning is most memorable by a hands-on approach, so I encourage everyone interested in dragonflies to acquire an insect net.
Although not everyone will wish to do so, the best way to learn to identify dragonflies is by catching them. Like butterflies, many species are easily identified in the field; but also like butterflies, some species may be identified only in the hand. The simplest way to learn their identity is to capture one, identify it in the hand, then either release it or “collect” it for a reference specimen. Take care not to catch tenerals (just emerged) unless you plan to keep them; they are very easily damaged if handled.
If you collect a dragonfly and plan to keep it, there are procedures that you should follow so the specimen is of greatest value to you and possibly to a larger collection to which you may someday donate it. There is really no justification for killing a dragonfly except for education or research, but your personal education or research can fall in those categories. No North American odonate is rare enough that collecting a few specimens for these reasons in any way endangers its populations, but you should be aware that collecting of any insects without a permit is prohibited in most parks and reserves. In addition, certain species are officially protected because of their rarity in a particular state, and the Hine’s Emerald (Somatochlora hineana), an eastern species, is federally protected.
If you wish to make a collection, here is a summary of the steps to follow to collect a dragonfly for a specimen.
1. Catch it.
2. Envelope it.
3. Acetone it.
4. Remove it.
5. Label it.
6. Store it.
Catch it Odonates are subject to predation, particularly by birds, and they are accordingly quite wary. They have quick responses and quick flight, so you must be even quicker. Even damselflies may move away rapidly, although they are sometimes easily approached. Dragonflies are considerably warier.
If your intended “prey” is perched in the open, just sweep the net sideways, trying to center it. If it is in dense vegetation, the best strategy is to come down from above, as a sideways sweep may just flip the vegetation out of the net and the insect with it. Lift the end of the net, and your captive will often fly up into it. Grasp the net below it and turn the net over so you can reach in and grab it. They tend to fly up, and many a dragonfly has escaped instantly when the collector opens the bag to look inside!
For a dragonfly in flight, sweep sideways and quickly flip the net bag over, trapping it inside. It is always best to swing from behind and below, the area of an odonate’s poorest vision. Both feeding individuals and those in sexual patrol flights may fly a regular beat, so you can anticipate their flight path. Don’t be surprised if they fly out and around you on every pass. I have found that standing next to a shrub or tree apparently makes me less conspicuous.
You can usually grab any dragonfly with impunity, but the larger ones have big mandibles and can pinch. Only a few of the largest species can actually draw blood when they bite, so If you are concerned, just watch what you are doing and grab them by the wings. Their wings are quite strong, without the shedding scales of butterflies. Again, tenerals are an exception to that statement.
Envelope it Place it, always with wings folded back, in a glassine (stamp) envelope labeled with locality and date. To save time and for recordkeeping, I use a field number for each collection based on the year: 08-1, 08-2, etc. You can put more than one individual per envelope, but they may chew on each other, so put their heads at opposite ends. I write “T” on the envelope for pairs in tandem and “C” for pairs in copula, as it is important to keep track of pairs and keep them together in a collection. Make sure you have a pen with indelible ink.
Acetone it After leaving your specimens in their envelopes for a while (for example, until you return home at night) so they can void their intestinal contents, kill them by immersing them briefly in acetone or injecting a drop of acetone into the thorax. Straighten the abdomen of each specimen, arranging the legs so they do not obscure the genitalia on the second abdominal segment of males. Line up each pair of wings so one lies under the other, and separate the forewings slightly from the hindwings to allow easier study of the wing venation. Put them back in their labeled envelopes and leave them submerged in acetone in a tightly closed plastic (e.g., Rubbermaid®) container for 12–24 hr. Cut off a bit of both lower corners of the envelope so the acetone drains when you lift the envelope out.
Acetone extracts fat and water from specimens, and they dry much better and with better color preservation than when merely air-dried. However, you should avoid breathing acetone fumes. Work in a well-ventilated setting.
Specimens with extensive pruinosity may become discolored in acetone. In particular, male spreadwing damselflies and pruinose male skimmers such as Common Whitetail and Western Pondhawk change color rather drastically, so I now prefer not to place them in acetone unless the environment is so humid that they may not air-dry adequately.
Remove it Remove your specimens from the acetone and leave them in the open for a few days so the acetone will evaporate. Preferably, have a well-ventilated spot away from people as it evaporates. Try to separate the envelopes for quickest evaporation. All dried dragonfly specimens are stiff and brittle, although those that have been acetoned are stronger and more resistant to breakage.
If you are unwilling or unable to use acetone, an alternative is to let the dragonfly die in the envelope; if it excretes feces from its abdomen, the abdomen dries better. Alternatively, you can kill odonates by freezing them. Make sure the abdomen is straightened rather than curved. Put the specimen in a dry and ant-proof place to dry thoroughly. Then continue as described below.
Label it All specimens should have the following information associated with them: locality, date, and collector (species name can be added later and changed if reidentified). Many collectors include habitat notes, at the very least something like “pond” or “slow, sandy stream” or “flying over clearing.” This information associated with the time collected is of additional value. Pairs in tandem or in copula should always be so indicated.
Dragonfly storage envelope
Dragonfly collection
Store it Store your specimens in a box protected from both humidity and possible pests such as carpet beetles, ants, or mice. For more useful and elegant storage, after they are dry, switch them to “Odonata specimen envelopes” (available from the International Odonata Research Institute) with the collecting information printed or written on a 3 × 5 card; the specimen can then be examined without removal from the envelope.
You can devise your own storage system for your specimens. Many collectors keep them in boxes of appropriate sizes with a few mothballs in each box, stored on a shelf or in a cabinet or drawer. If you think your home is pest-free, you can take your chances without mothballs, but you should check for bug damage frequently to confirm this.
Logically, the wings of pinned dragonfly specimens are usually spread, but for the most part they are not spread in enveloped specimens. You may wish to store a few specimens with wings spread for photography, drawing, and dorsal or ventral views of the specimens without having to remove them from the envelope. Also, at least a few specimens of odonates with patterned wings should be stored with wings outspread.
To examine the wings of just one side, you can remove the specimen from the envelope and carefully (from front to back) slide a piece of white paper or card between the left and right wing pairs.
The larvae, of course, are collected in entirely different ways. The best way is with a strong dipnet or a metal net like a large tea strainer. Sweep it through aquatic vegetation or drag it over the bottom substrate, swish it around in the water to wash out the sediment, and then poke through it to see what is moving. Many larvae will remain immobile, so you’ll have to search for them. A good way to find stream larvae is to stir up the bottom sediment (rocks, sand, mud) while holding your net just downstream. Some larvae can be found by lifting rocks out of the water and scrutinizing them. This is most productive in tropical streams but would also be effective in the Southwest, where rock-dwelling dancers and shadowdamsels live.
Larvae to be retained for study should be preserved in 80% ethanol in vials that seal very well; evaporation is the bane of a preserved collection. Labels should be written with indelible ink on good archival paper; I have used parchment paper for years.