ODONATA COLLECTING INSTRUCTIONS
Exuviae are the cast larval skins of the penultimate instar
of Odonata. They provide important information about where species
live and where they emerge. Since the larval characters are quite
evident, most exuviae are identifiable to species level. Since
exuviae are not living, participants not wanting to collect and
kill living odonates can make a great contribution just by conducting
surveys for exuviae along rivers, streams, and ponds. Exuviae
indicate the presence of larval populations and past breeding
populations at a particular locale, and therefore, they are valuable
records for the survey. MOS participants are encouraged to collect
exuviae and note the location and conditions where they are found.
The UMMZ has an outstanding collection of Odonata exuviae, and
many are catalogued in a database. Exuviae should be documented
with as much care as adults and larvae.
Figure. 1. Macromia illinoiensis exuviae
Figure 2. Anax longipes exuviae on cattail
Odonata larvae represent a different challenge for collectors. You must remember that most of the time they are unseen residents of aquatic systems. You will for the most part only catch them when sampling the streams, ponds, seeps, and lake bottoms. Try to minimize disruption to the site where you are collecting. Unless you want to get wet, chest waders or hip boots are a good idea. Some aquatic situations are potentially dangerous to a lone collector, so it is advisable to collect with a companion. Bogs and fens and deep-muck-bottomed lakes can be places where a person collecting alone might get stuck for hours. Streams and rivers have their own potential dangers. If you can avoid collecting alone, please do so. Additionally, in or near metropolitan or mining areas, you might come into contact with polluted waters that are potentially hazardous. Waters might be polluted with organic matter or heavy metals or be very acidic. It is always wise to inquire with local health officials to see if any such warnings exist for streams, lakes, etc. that you may be working in. Again, a good set of chest waders provide a measure of safety.
For aquatic collecting, you will need a net designed for aquatic sampling, such as a D-net or similarly strengthened net with a long handle and strong nylon mesh (500-250µm mesh is best). You can also use standard kick-seines in riffle areas. Standard insect nets are not good for this purpose. (See the appendix for suppliers.) You can use a small dip net for pools and vegetated areas to catch species that are on the aquatic vegetation or near the surface. Seeps and very small streams are easily disturbed, so use as much care as possible when collecting in such habitats.
Samples can be dumped into a shallow pan (preferably a white enamel or plastic tray) to easily search for odonate larvae. Specimens to be preserved may be dropped into 70% ethanol or isopropanol. Specimens to be kept alive should be separated by size to avoid cannibalism and predation.
Make sure that data accompanies preserved specimens - use either pencil or India ink on rag paper (available from the MOS) to prevent fading or leaching of ink.
Collecting adult Odonata, especially the Anisoptera, can be quite challenging, and often, a lot of fun; it's a lot like fishing. Several hours spent on or in the water with only a few "keepers" to show for all the effort! Depending on where and what you collect, the techniques will differ. The most effective technique is to wait until the adult dragonfly is almost past you, and then swing the net from behind. A frontal assault nearly always end in favor of the dragonfly. Swinging the net at an oncoming dargonfly might also result in a headless or tailess specimen. The combined speeds are just too much for the exoskeleton if the specimen hits the ring of the net. Some species are more easily captured when they alight on a perch -- such as many Libelluidae. Others might be caught while they are basking on logs -- such as some gomphids and aeshnids. Corduliids are more easily captured early in the mornings or later in the afternoons to early evening. Again, a sweep from behind where the males are patrolling or female oviposition areas are more likely to succeed. Keep in mind that any observations you make on oviposition, mating, or predatory behavior are valuable, especially for some of the lesser-known species. Watching the habits of the species you see before you try to catch them will also yield greater success as well as useful behavioral information.
Several items are necessary for successfully collecting and preserving Odonata.
First, the major piece of equipment you'll need is an insect net with at least a 15" diameter hoop. Some collectors have been known to use a 36" diam. hoop with a 5 ft. handle! Most however, do fine with the standard 3 to 4 ft. handle. There is a debate on which color netting is best, - green, black, or white. This seems to be a matter of personal belief as to which is best.
Second, you'll need a supply of "paper triangles" (Fig. 3) to hold the captured adults. Place a single specimen per triangle, and record your field note number on the flap of the triangle (in pencil). Williamson (1916) recommended the use of newsprint to make the triangles.
Figure 3. Template for making paper triangles (from Williamson 1916).
A porous paper is definitely recommended. You could also use the small kraft envelopes known as coin envelopes to store most specimens. If a collector just places the specimens in a killing jar, their wings may set in an unusual position after they die. Glassine envelopes such as those used by stamp collectors may also be used for field storage. The MOS will provide its particpants will a supply of glassine envelopes. (See Appendix 2 for more on this topic).
After the specimens have been placed in envelopes you'll need to kill and preserve them. The currently favored method is to place the entire paper triangle or envelope into a container of acetone. After 24 hr., remove the specimens and allow them to air-dry for several days. This method generally seems to remove all of the fats from the specimens and preserves many of the brilliant colors, especially blue coloration (except for the eyes). For very hairy specimens, such as some Corduliidae, this method may mat the hairs. Freezing specimens may also work, providing that they are air-dried afterwards as quickly and thoroughly as possible. However, specimens killed in this manner are more likely to mold. Another common method of dispatching specimens is to place them in a killing jar, either charged with cyanide (the old-fashioned way), ethyl acetate, or acetone. Ethyl acetate is safer to use and easier to purchase, and is recommended for those not wanting to use the acetone method. There are some other more elaborate methods for killing and fixing specimens, and you can find out more on this topic via the Internet on the IORI web page. The most important aspect is to thoroughly dry your specimens as quickly as possible, without subjecting them to undue heat. Be sure to prevent the formation of mold on the specimens, as it will render them nearly useless. Perhaps even silica gel drying agents would be useful for this purpose. This is still a fertile field for experimentation on the best methods of color preservation.
In a nutshell, all you need to collect adult Odonata is a standard aerial insect net, a large peanut butter jar with an inch of plaster in the bottom soaked with ethyl acetate or acetone, a pencil, a field notebook, and many small paper triangles. The total cost for equipment should be less than $20.00. The other thing you'll need is patience! That's priceless.
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Figure 4. 3 x 5 card and envelope storage system.
Most large collections of Odonata are stored in a simple system using cellophane or plastic envelopes slightly larger than a 3 x 5 inch index card (Fig. 4). The card contains all of the data for the specimen arranged as illustrated. The specimen is placed in the envelope (well-dried, of course) and the flap is folded over on the right side. Specimens are stored either vertically on edge, or flat. There are tray systems in use that provide neat and organized methods of storage. For temporary use, plastic shoeboxes provide an easy and inexpensive storage system for the card and envelope method. Because they are not pest-proof, they are not a good idea for permanent storage. The plastic envelopes are very inexpensive and are available from the IORI in any quantity, and the MOS can make some available in small quantities to its participants. The MOS does not recommend pinning and spreading Odonata like butterflies. This method takes up too much space, makes the specimens harder to handle, and if any parts come off the specimen, they are easily lost. In fact, the 3x5 envelopes are cheaper than insect pins! If you are collecting for the MOS, it is acceptable to keep the specimens in paper triangles or envelopes and let the UMMZ take care of the transfer to the 3x5 system.
Storage of larvae and exuviae. At the UMMZ larvae are stored in glass screw-top vials and jars containing 70% ethanol (Fig. 5). However, if you cannot obtain ethyl alcohol, isopropyl may be used instead. Never use methyl spirits (wood alcohol). Rubber-stoppered vials may also be used. For the best protection of specimens, the use of Polyseal(R) caps are recommended on screw-top vials. Larger 2 and 8 oz. jars use polyethylene liners in the caps. These are available from a variety of sources. Labels are either handwritten in India-ink or printed with a multi-strike ribbon on a dot matrix or letter-quality printer. It is not advisable to use laser-printed labels because they are unreliable for long-term storage.
Figure 5. Larvae in stoppered vial and 2 oz. jar.
Exuviae may be stored in a number of ways - inside vials, 3x5 envelopes, or pinned. Many collections store their exuviae in alcohol, or dry, in vials. The UMMZ has all three methods in use, depending upon the original condition and storage method of the exuviae. One practice is to place the exuviae into clear 3x5 envelopes with the data on the card. That way, all is visible, and if parts come loose, they stay inside the envelope. However, you have to be careful to avoid crushing the specimen. For this reason, storage in alcohol is a better method, especially if you want to manipulate the exuviae for measuring, etc.
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Of course, a specimen without data is practically worthless. At minimum, you should record the following for MOS purposes:
1. STATE and COUNTY
2. LOCALITY: nearest town, rd. miles from major intersection, State or National Forest, name of lake, etc.
3. TOWNSHIP, RANGE, & SECTION: If you have the MUCC map, this will be easy. You may also use geographic coordinates - latitude and longitude.
4. FEATURE: stream, bog, fen, river margin, etc.
DATE: Spell out or in this format: MONTH/DAY/YEAR - Spelling out or
abbreviating the month is preferred. Roman numerals are also used for the month. Using a numeric for the month may confuse someone if the don't know that the US system is MM/DD/YYYY rather than the european preference of DD/MM/YY.
5. COLLECTOR: Your name or whoever collected the specimens.
6. COLLECTION NUMBER: It is a good idea to use a numbering system so that you can use a number in your field notebook that cooresponds to a specimen or lot of specimens from a single collecting event. My preferred system is simple: Your initials followed by the date in descending order and then a number or letter for the collecting event. Numbers are better for events if you anticipate more than 26 events in a day. Example: I have a specimen with the number MFO960702-1. This tells me that I collected it on July 2, 1996 and it was the first site I collected at that day. I may have collected 20 specimens representing 9 species from that collection. This way, all the specimens are correlated with that collection event. You may have another system, but I think the above is the most flexible and informative, if you apply it consistently.
7. NOTES: Provide any additional biological or ecological information here. Water temperature, stream or lake habitat type (riffle, undercut bank, pool, debris dam, etc.), substarte conditions (sand, muck, gravel, peat, boulder, woody debris, etc.), pH, turbidity, dominant vegetation, air temperature, cloud cover, wind, mating or oviposition behavior, etc.
This is basically all you need to provide for a rather complete set of data for a collection. Minimally, the basic locality and date information is quite acceptable.
The above information should be kept in a field notebook. I like to use cloth-bound 5" x 8" notebooks with lined pages. "Blank books" are now often available from book outlets for less than $4 each, and they have enough pages for a season's worth of collecting. Spiral-bound notepads don't hold up as well, but are acceptable. There are also waterproof field notebooks in a variety of styles (Rite in the Rain) available from some vendors. Again, the Collection Number system described above works well, and is easy to use in your field notes. The above data should be kept in the journal, alsong with any other field notes that you think are worth recording.
Unfortunately, there are no Peterson-style field guides for Odonata. For many of the common species, this would probably work, but many Odonata require examination under magnification to determine the identity. In the past several years, there have been "local" field guides with excellent illustrations and photographs of living specimens. If you are just starting out, try to learn the identity of the common species first, then perhaps the species in a small area. As you work your way through the levels of identification, you'll gain more confidence in your ability to identify species on a larger scale. You do not necessarily even have to learn to identify specimens to the species level for the MOS, family and genus may be all that is needed so long as someone else does the determination of the species later on.
Larval Identification - The MOS will soon have a species-level guide for identification of larval Odonata found in Michigan. It is available on the MOS WWW site. However, a printed guide will eventually also be available. For generic-level references, the following publications will be of use:
Hilsenhoff, W. 1995. Aquatic Insects of Wisconsin: keys to Wisconsin genera and notes on biology, habitat, distribution and species. Natural History Museums Council, Univ. of Wisconsin-Madison, No. 3.
Needham, J. G. amd P.R. Needham. 1962. A guide to the study of freshwater biology. Holden-Day, San Francisco. 108 pp.
Pennak, R.W. 1953. Freshwater invertebrates of the United States. Odonata, pp. 522-540. Ronald Press, NY. 769 pp.
Westfall, M. J. and K. J. Tennessen. 1996. Odonata, pp. 164-211, in: Merrit, R. and Cummins. An Introduction to the Aquatic Insects of North America., 3rd. ed.. Kendall-Hunt Publishing Co., Dubuque, IA.
Adult Identification - The classic works on the Odonata of North America by Needham and Westfall (1955) and Walker (1953&endash;1966) are hard to find, except in libraries. They rarely turn up in used book sellers. Unfortunately, this situation has made it difficult for amateurs to get authoritative works for identification of odonates. Recent efforts by various people have improved the situation, especially the Westfall and May (1996) book on damselflies of North America. Guides to local faunas are also appearing and are aimed at the less-technically experienced audience.
The following recent (and in print) publications will be useful for identification of some of the adult Odonata that you'll encounter:
Carpenter, V. 1991. Dragonflies and Damselflies of Cape Cod. Cape Cod Mus. Nat. Hist. Series No. 4. 80 pp. Brewster, MA.
Dunkle, S. W. 1989. Dragonflies of the Florida Peninsula, Bermuda and the Bahamas. Scientific Publishers, Gainesville. 155 pp.
Dunkle, S.W. 1990. Damselflies of Florida, Bermuda, and the Bahamas. Scientific Publishers, Gainesville. 150 pp.
Holder, M. 1996. The dragonflies and damselflies of Algonquin Provincial Park. Algonquin Park Tech. Bull. No. 11. 40 pp.
Westfall, M. J. and M. L. May. 1996. Damselflies of North America.
Scientific Publishers, Gainesville. 650 pp.
Garman, P. 1927. The Odonata or Dragonflies of Connecticut. Guide to the Insects of Connecticut, Part V. Hartford. 331pp.
Morgan, Ann Haven. 1930. Field Book of Ponds and Streams. Putnam's and Sons, New York. 448 pp.
Needham, J. G. and M. J. Westfall, Jr. 1955. A Manual of the Dragonflies of North America (Anisoptera). University of California Press: Berkeley, California. 615 pp.
Walker, E. M. 1953. The Odonata of Canada and Alaska, Vol. 1. University of Toronto Press: Toronto, Ontario. 292 pp.
__________. 1958. The Odonata of Canada and Alaska, Vol. 2. University of Toronto Press: Toronto.
Walker, E. M. and J. S. Corbet. 1975. The Odonata of Canada and Alaska, Vol. 3. University of Toronto Press: Toronto.
Williamson, E.B. 1916. Directions for collecting and preserving specimens of dragonflies for museum purposes. Museum of Zoology, Univ. of Mich. Misc. Publ. No. 1, 16 pp.
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