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Collection and Preservation of Odonata
Abstracted from The Dragonflies and Damselflies of Ohio.
Why collect Odonata at all? Why not use binoculars, as ornithologists do? The problem is that some species of Odonata simply cannot be identified without placing them under a microscope where detailed examinations can be performed. From the perspective of the survey, we have been very reluctant to include records where a specimen does not exist in a museum. Collectors can add significantly to our knowledge of Odonata if their collecting is done with care.
Before any specimen is collected, you should be able to answer these questions affirmatively: 1.) Is the collection being made for valid scientific or educational purposes? 2.)Is the species being collected common enough in the local area that the collection of this specimen will not adversely affect it?
Given the immense reproductive potential of insects and their short lives, the collection of a few is usually not enough to have any real impact on a population. Even in the worst case, if a human would collect all of the Odonata of a particular species at a pond, their powers of flight would enable other individuals from nearby ponds to recolonize.
This is not to suggest that collecting cannot have disastrous consequences. Overcollecting at a few popular sites can be a problem. In addition, there are rare species and rare habitats in the state that cannot support much collecting. For those reasons, the Ohio Odonata Survey used the following collecting guideline: no more than 4 specimens of a given species at a given site are to be collected in a given day. Particular care should be taken not to overcollect rare species or overvisit rare habitats.
In Ohio it is illegal to collect Odonata from a variety of publicly held properties without permission. In general, you should get permission from the appropriate agency managing the site you want to collect from. The Ohio Department of Natural Resources controls collecting at State Parks, Natural Areas and Preserves, and on state wildlife lands. Local park systems may have regulations concerning collecting in metropolitan or county parks. The U.S. Fish and Wildlife Service regulates collecting at national wildlife refuges. Most of these agencies will allow collecting at most sites with prior approval. Also, it is important to note that the state or federal agency you contact might have a local caretaker, ranger, or manager who should also be informed of your plans; dont assume that the central authority will contact the local authorities for you. Of course, you should also get permission from local landowners before collecting on their land or crossing their property. Ohio law grants landowners control over streambeds in many situations, so you might be trespassing even if you are in the middle of a stream. Finally, remember it is always illegal to take an endangered species without a permit; acquaint yourself with the endangered species you are likely to encounter before collecting in a given habitat.
Data to record:
Without collection data, a specimen is useless for anything but display or identification practice. From a scientific standpoint, a specimen without collection data is worthless. Therefore, in order to ensure that specimens are not wasted, it is important to be sure to accurately locate the collection site and date, and to be sure that this data stays with the specimen as it is being prepared for long-term storage.
Labeling begins with a field notebook. Upon arriving at a collection site, you should first record the exact location. This would include the state, county, and township (section if possible), as well as the street "address" as near as it can be determined in a rural location. Since Odonata are usually collected near bodies of water, the name of the body of water should be included. Often, it is useful to draw a crude map in your field notebook so that you can return to the site at a later date. This map would show local roads, railroad tracks, bridges, or other landmarks, as well as indicate exactly where along the shoreline the specimens were collected. Although some of this data will not accompany the specimen to the museum, it will help you reconstruct your collecting trip at a later date. Other worthwhile data to record at this time would be time of day, temperature, weather conditions, and so forth.
Ultimately, the data label to accompany the specimen should have this type of format:
This label includes: the state, county, township, section, body of water (with its intersection to a local road), latitude, longitude, a special code (L1) to indicate how close to the latitude and longitude position the collection was made, the date and time of collection, the name of the collector, and a note on the special circumstances surrounding the capture. Abbreviations have been kept to a minimum to reduce later confusion. In this case, the label also notes that both of the specimens taken were flying in tandem, and that they had landed on water willow. The date has the month written out to avoid any possible confusion. The time information (written in "military" or 24-hour format to reduce confusion between a.m. and p.m.) may be of use to future researchers doing behavioral work.
To insure a common set of place names, we encourage the use of the Delorme Ohio Atlas and Gazetteer as a standard source for names of places, roads, and bodies of water. Note, however, that the Gazetteer does not include section data for townships; these must be obtained from topographic maps of the area.
Perhaps the best method of pinpointing location is through the use of the Global Positioning Satellite System (GPS). GPS units are handheld, relatively accurate, and inexpensive. While some of the least expensive units are not able to receive satellite signals under heavy canopy cover, most units will work in the middle of a stream (one option under heavy canopy cover is to return to the site in winter to take a GPS reading). In general, it is best to set your GPS to use the UTM projection and the degrees/minutes/decimal format.
If you dont have access to a GPS unit, but are able to locate precisely your collection sites on a map, you could use any of a number of commercial mapping programs in conjunction with a home computer to determine the latitude and longitude of your collection sites.
In addition to the latitude/longitude information, the Ohio Odonata Survey has adopted a system of "precision codes" to help determine how close to the lat/long position the specimen was caught. Thus, if you set out and collected along a stretch of river, you could determine your location with the GPS one time, and use the following code (devised by the Ohio Lepidopterists) to tell anyone reading the label how close you were to that point:
Table 1 Precision Codes used by the Ohio Odonata Survey:
|For streams and rivers (linear)||For other situations (area)|
|L1 within ½ mile or less||S1 within 200 feet|
|L2 - within 1 mile or less||S2 within a ¼ mile circle|
|L3 - within 2 miles or less||S3 within a ½ mile circle|
|L4 - within 6 miles or less||S4 within a section|
|L5 - within 36 miles or less||S5 within a 2 mile circle|
|L6 - within ½ the distance of the state||S6 within a township (36 sq. miles)|
|L7 - within the state||S7 within a county|
|S8 within ½ of the state|
Obviously, the more specific one can be as to the location, the more valuable the data is.
Five basic pieces of field equipment are needed. A set of cards or paper slips on which to write temporary labels; a pencil or pen (with indelible ink!); envelopes or bags in which to place the specimens, and a sturdy container to keep the specimens from being crushed, and a collecting net.
A good insect net for Odonata will have a diameter of at least 18 inches, an open mesh net, and a handle at least 4 feet long. A bigger net is harder to fly around and requires a less accurate swing from the collector. Dragonflies are fairly large insects and an open mesh (1/4" or so) allows air to pass through the net more easily, resulting in an easier and faster swing. A finer mesh is needed for damselflies, however. Other desirable features of a net include a collapsible or sectional handle to facilitate travel; a lightweight handle made of aluminum (remember this however, when standing in a lake during a thunderstorm or when working near electrical cables!), and a thin but stiff rim for the net.
Experts are somewhat divided on the best way to effect the capture. Many experienced collectors swear by swinging the net so it comes up behind the dragonfly. The net, in this case, is coming up from behind the dragonfly, which is then less likely to see it. At the end of the swing, twist the net so that the rim blocks the opening to the bottom of the bag; keep twisting the net so that the bag is folded around the rim.
Place the net on the ground and locate the specimen in the net. Use one hand to hold the net around the specimen so that it is immobilized, and reach through the rim with the other hand to claim your prize. When your hand reaches the dragonfly, fold the wings over its back and hold the dragonfly by the wings at their base. In this position, the dragonfly cannot bite (on occasion, some of the larger specimens can give a painful bite). Now, withdraw your hand from the net and slide the specimen into the collecting envelope. With the specimen on its side in the envelope and its wings still folded over its back, use your free hand (that was holding the net) to hold the envelope taught around the specimen as you release the wings. Immediately fold the envelope closed.
In terms of envelopes, glassine envelopes, made of waxed paper, are the best for field use. These envelopes are cheap and reusable, and you can write directly on them if you have to. Many collectors, however, choose to write temporary labels on separate slips of paper; this allows the envelopes to be reused and prevents damaging the specimen while writing the label. All specimens should be labeled in the field, at the very least with a temporary label (7/23/98 - site A) that can later be expanded with data from a field notebook. Labels should be made with pencil or with an ink that resists both acetone and water. With the specimen labeled and sealed in its envelope, transfer the envelope to a box so that the specimen doesn't get crushed. Field boxes can be bandage containers, plastic sandwich boxes, small plastic tackle boxes, or virtually any container that will hold a specimen yet still slip into a large pocket or fanny pack.
Collect from a variety of habitats. Small streams will yield a different fauna than larger streams; bogs will be different then fens; lakes will differ from ponds. As you do your collecting, be sure that you have permission to collect on whatever land you are on. Get permission to enter private land, and remember that some public land such as State Parks and Nature Preserves will require a permit. Otherwise, no permit is required to catch non-endangered Odonata in Ohio.
One last note on collecting - when you collect is at least as important as where you collect. By studying the flightlines on the web pages you will have some idea of what time of the year to look for a given species. Still, these are only guidelines. Remember that much of the information on the time of year that the adults are flying was collected by academic biologists and seasonal naturalists; the flight periods for some species may be linked as much to the opening and closing of classes at colleges and universities as much as the biology of the species. Great contributions to our knowledge of the biology of Odonata in Ohio can be made by anyone with the time to collect outside the traditional summer season.
Beyond the season of collecting, the time of collecting during the day is critical. Generally, most species are most active at the warmest time of the day. Still, many interesting species have different habits, such as flying at dawn or dusk. Sometimes, a given species will congregate at the water body at a particular time of the day, and spend the rest of the time scattered over the landscape foraging for food.
Preservation and Storage
Immediately upon return from the field, specimens should be processed for long-term storage. The adults should be immersed in a 100% acetone solution. This is most conveniently done in a plastic container that can be sealed tightly; test the plastic beforehand to make sure the acetone doesnt "melt" the plastic. The acetone itself can be purchased at most hardware stores; this commercial grade is much less expensive than laboratory grade acetone.
In addition to its use as a paint thinner, acetone is sold commercially for use as fingernail polish remover. Despite this innocuous use, acetone can be dangerous. Like any organic solvent, acetone should be treated with respect, organic solvents in general are suspect as possible carcinogens and as agents for carrying toxins into the body across the skin. Use it only in a well-ventilated area, do not inhale the vapors, do not let the acetone come in contact with the skin, and be sure to keep it away from flames. Acetone is very flammable. It is probably not a good idea to carry much acetone with you in your car because of its flammability.
Place the specimens (still in their envelopes) in the plastic container. Make sure that the acetone fills each of the bags. The acetone will quickly kill any specimens that have remained alive until this point. At this point be sure the specimens are straight, with the wings held flat above the body, and all critical features in clear sight. Once you are certain that all of the envelopes contain acetone, seal the container and place it in a secure place. Large dragonflies should be left in the acetone 8-10 hours (overnight); smaller dragonflies and all damselflies only need 4 to 6 hours of acetone treatment.
While the acetone treatment is proceeding, prepare the permanent labels according to the directions given earlier. Be sure the paper used for the labels is of good quality. For adult specimensleft-hand corner, while identification information (including the name of the person , use a 3x5" unruled index card. The label information is placed in the upper doing the identification and the date the identification is madehand corner. It is not unusual to type out the collection data and later hand-write in the ) is placed in the upper right identification dataink or in #2 lead pencil. Lately, the proliferation of laserwriters has provided a . For both adults and larvae make sure the labels are written in indelible convenient way to create labelsstable even in alcohol. Laserwriters fuse a carbon toner onto the paper, and it seems to be
After the acetone treatment has been completed, pull the specimens out of the acetone and allow them to dry on a piece of paper towel. Place the index card with label information inside a permanent clear plastic Odonata envelope. The opening of the envelope should face to the right as you read the label information. Next, slide the insect into the envelope so that it is between the card and the front of the envelope; the insect should face to the left. If any body parts have broken off, be sure to get them in the envelope as well. The envelope is closed by rolling the flaps to the right of the envelope over the card; this pins the specimen in front of the card and the flaps are secured behind the card
For long-term storage the adults must be protected from extremes of humidity and from insects. Both goals can be accomplished by storing the insects in sealed plastic containers such as those used for storing food. A sealed container should eliminate the danger of damage to the specimens by dermestid beetle larvae, psocids and fungi, all serious pests of insect collections. To achieve this protection, however, the specimens must be sealed up as soon as they dry from the acetone treatment. If the container is not airtight, or if you are paranoid, additional protection against insect pests can be achieved by placing a small amount of insecticide in the container. No-pest strips or pet flea collars can be cut into small pieces for this purpose; biological supply houses also sell crystalline insecticides and containers for the same purpose. Periodic freezing at -20o C or colder is a non-toxic way to kill any insect pests in your collection. Likewise, adult specimens can be placed over a container of water and microwaved for 10 to 20 seconds.
Some prefer to use cardboard boxes to store large collections of specimens. This method works well if the boxes are then placed in a well-sealed container such as the cabinets used in museums. The Ohio Odonata Society has its own design which you can see here.
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