19 March 2012

Wanted: Early adult Common Green Darners

We have received our first report of Common Green Darner (Anax junius) for the state: 18 March near Pointe  Mouille in southern Wayne County. While nearly every dragonfly enthusiast eagerly awaits the start of the field season, not too many of us are ready with a net to snag the first green darners of the season (which in any event are not too easy to catch). Thus, the earliest adult voucher we have is in mid-April.

With the incredibly early spring this year, just about anyone has the opportunity to provide a new early voucher date for Common Green Darner. We invite you to get out your nets and snag one anywhere in the state. Let us know in the comments if you get one! Don't forget, you can see this page on how to collect, prepare, and submit vouchers. The voucher template is now available on the downloads page. If you need glassine envelopes, contact Mark O'Brien (mfobrien AT gmail DOT com) and he can send you a bunch.

Establishing flight seasons for each species is just another valuable piece of data that can be obtained from collecting vouchers. Another potential use for sampling early-arriving odonates is future molecular sampling to determine source populations. Therefore, we'd prefer a voucher. However, Common Green Darner is among the species in which a photograph is acceptable. Please note it needs to be a mature male, or female or immature male (the latter unlikely this time of year) if "bullseye" on forehead is clearly visible in photo. See the post on photos regarding instructions on submitting the photo to Odonata Central, and then indicating it on your voucher template.

Good luck!

08 March 2012

Voucher specimens required

For Odonata records to be considered valid and used in the Atlas, a voucher specimen must be deposited in the UMMZ insect collection (or at another institution). There are a few exceptions of easily identified common species for which photographic records will be considered. See this post for details.

There are many reasons for this requirement. Many odonates are not reliably identified through photographs. Without a specimen, there is no material available for taking measurements (which may vary by location), or for molecular and/or genetic analysis (a number of species that are new to an area or even new to science have been "found" in museum collections after such testing). In the future, specimens may be used in ways we cannot imagine today. I'm sure the early collectors of some of the odonates in the UMMZ collection, which are over 100 years old, never imagined projects like the International Barcode of Life!

We are aware some people may not want to bother with collecting. You can contribute by letting us, or another collector, aware of potential new records so that a proper voucher can be obtained, if necessary.

Some people may not even want to that because they have an ethical objection to killing insects. We can only say that adult dragonflies are typically very short-lived  insects with very high reproductive rates.  The adults you see are a small proportion of the local population, most of which are underwater, living as nymphs. Your very judicious collection of a representative voucher will have no impact on the population as a whole. In addition, if you are observant, you may see the nymphal exuviae of recently emerged adults. Collecting those exuviae are actually quite reliable ways to determine the identity, and of course, approximates an actual emergence date for the adult. Since the collection of exuviae does not impact the life of the adult specimen, exuviae are accepatble means of vouchering threatened /endangered species. For information on collecting exuviae, look here.

There is great scientific value in having a specimen beyond just a data point representing the distribution of the species.Voucher specimens are permanent, tangible, and verifiable. For an excellent overview of the role of voucher specimens, see this Biological Survey of Canada article.

We have put together a page on how to prepare and submit voucher specimens to the MOS.

07 March 2012

Permissible photographic records

The MOS will accept photographic documentation for county records to be included in the Atlas of the following species ONLY. Further, in order to be considered for acceptance, these photographs will need to be submitted to Odonata Central.

You'll need to register for a free account there, and upload your photos. These records must contain the date of collection, and the specific location including geocoordinates. Once you have submitted each record, it will appear as "pending" in the Decision field. After the record has been vetted, the Decision will appear as "Confirmed." At that point, you can fill out the MOS data entry template (available on the download page) with all needed data; use the OC number as your "Fld No". You can email the spreadsheet with one or many photographic records at any time to Mark O'Brien (mfobrien AT gmail DOT com). Please keep physical vouchers and photographic records on separate spreadsheets, and indicate that your submission is for photos.

Acceptable species for photographic records:

Ebony Jewelwing (Calopteryx maculata) -- mature male only
Violet Dancer (Argia fumipennis violacea) -- mature male only
Aurora Damsel (Chromagrion conditum) -- mature male only
Orange Bluet (Enallagma signatum) -- mature male only
Fragile Forktail (Ischnura posita) -- mature male only
Common Green Darner (Anax junius) -- mature male; female or immature male only if "bullseye" on forehead is clearly visible in photo.
Prince Baskettail (Epitheca princeps)
Calico Pennant (Celithemis elisa)
Halloween Pennant (C. eponina)
Eastern Pondhawk (Erythemis simplicicollis)
Spangled Skimmer (Libellula cyanea) -- stigma must be visible.
Widow Skimmer (Libellula luctuosa)
Twelve-Spotted Skimmer (Libellula pulchella)
Four-spotted Skimmer (Libellula quadrimaculata)
Blue Dasher (Pachydiplax longipennis)
Eastern Amberwing (Perithemis tenera)
Common Whitetail (Plathemis lydia)
Band-winged Meadowhawk (Sympetrum semicinctum)
Black Saddlebags (Tramea lacerata)  

If you have high quality photographs of other potential county records, please let us know. We can include them as "hypothetical" species, and/or attempt to obtain a voucher. If your photograph is of an actual voucher specimen that will not be deposited in the MOS collection, we can certainly use it as a valid record depending on the circumstances (ability to verify the identification, etc.).

Collecting Odonata Nymphs

Collecting and Preserving Vouchers of Odonata Nymphs

It's easy to see why adult Odonata are so popular, but it’s important to remember that the aerial adult stage is just a small fraction of the life cycle of an ode. Since the nymphs (or larvae, depending on which term you prefer) are found in water, they are less obvious, nor are they as easily identified as the adult stage. However, collecting nymphs is a good way to record what's living in the aquatic habitats.

Ethan Bright and Joel Wiechsel in a stream in Livingston Co., 1998.

The techniques used for sampling nymphs differ, depending on whether you are collecting in moving water (lotic), such as a streams and rivers, or still waters (lentic), such as lakes and ponds. Lotic habitats may range from tiny creeks to large rivers. You will for the most part only catch nymphs when sampling the streams, ponds, seeps, and lake bottoms. Try to minimize disruption to the site where you are collecting. It’s standard to stand upstream from your kick-seine or D-ring net and dislodge the substrate so that the insects float into the device you are using. With sampling along the edge of banks and ponds, it’s typical to swish the net about in short strokes and then examine the contents.

Unless you want to get wet, chest waders or hip boots are a good idea. One can get by with wearing an old pair of sneakers, but spending a couple of hours in water can get old. With waders you avoid leeches, stay comfortably dry, and at the end of the day, your feet will feel so much better. 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. Floating bog-mats can be dangerous, too. Streams and rivers have their own potential dangers. If you can avoid collecting alone, please do so. Additionally, in or near metropolitan areas, you might come into contact with polluted waters that are potentially hazardous. Waters might be polluted with organic matter or with sharp debris. A good set of chest or hip waders provide a measure of safety. I do not advocate wearing sandals or going barefoot when doing aquatic sampling, as there are too many ways to acquire an injury from glass, metal, or sharp rocks. In addition, algae-covered rocks can be slippery. Avoid wading where you cannot see the bottom!

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 (500-250┬Ám mesh is best). You can also use standard kick-seines in riffle areas. Standard round insect nets are not good for this purpose. Small aquatic dip nets may be improvised from aquarium nets, strainers, etc. Larger D-ring nets can be purchased from vendors such as BioQuip. A white plastic or enamel pan is essential for examining your scoops of debris and muck in the field, and for separating out the nymphs. Much of the technique is pretty standard benthic invertebrate sampling, which can be found in many reference sources, such as this pdf.

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. Your samples can be stored in plastic vials, screw-top glass jars, or polyethylene "whirl-pack" bags. Some researchers keep their nymphs in water, and then preserve them at the end of the day by first dropping them into boiling water (which kills them instantly), and then placing them into ethanol.

Make sure that data accompanies preserved specimens - use either pencil or "pigma pens"on rag paper or card stock to prevent fading or leaching of ink.
Of course, in addition to Odonata nymphs, you will find a lot of other macroinvertebrates in your nets. If there are watershed surveys in your area, you may want to check with those groups to see if they might be interested in the other insects that you find. Caddisflies (Trichoptera), Mayflies (Ephemeroptera), and Stoneflies (Plecoptera) are commonly found while sampling.

Things to note during stream surveys:
•Type of habitat - riffles, cobbles, woody debris, sloughs, vegetated substrates
•Approximate width and depth of stream where sampled. Size and depth of lake, if a lentic habitat.
•Type of substrate - sandy, rocky, mucky, etc.
•Temperature, if possible
•Color of water - clear, tea-stained, turbulent, etc.
•Type of shoreline - high banks, rocky, etc.


So long as they are inside rigid containers, you can send exuviae in the dry state.

However, for specimens in alcohol, there are certain regulations for shipping that must be followed. It may be easiest to hand carry the specimens and pass them along to the MOS in person. If you wish to mail specimens to the UMMZ, please go to the following website for information on mailing wet specimens.

I'll admit that sampling for nymphs isn't nearly as exciting as trying to net a flying adult, but in terms of real science, there is a lot that we don't know about the immature stages of many odes. You may find that catching nymphs and trying to rear them to adults is a fun and rewarding experience. With today's plethora of digital recording devices, you can make movies of nymphs feeding, record a time-lapse movie of emerging adults, and whatever other behaviors that interest you.

In terms of trying to identify them, the place to start is here. Although the Michigan Odonata Larvae pages haven't been updated in a few years, it's the best thing out there so far.

05 March 2012

Collecting dragonfly exuviae

Exuviae are the cast nymphal (or larval, depending on which term you are most familiar with) 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. Exuviae are not living, so participants not wanting to collect and kill living odonates can make a contribution just by conducting surveys for exuviae along rivers, streams, and lakes. In addition, it has been recognized by the U.S. Fish and Wildlife Service that exuviae collections are acceptable means of documenting the presence of threatened/endangered species of Odonata. Exuviae indicate the presence of larval populations and past breeding populations at a particular locale, and therefore, they are valuable records for the Atlas. 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 most are catalogued in a database. Exuviae should be documented with as much care as adults.

To collect an exuvia, carefully remove it from the substrate that is resting on. You may wish to photograph it in situ before removing it. Note the type of substrate that is is resting on, and the height/distance from water. Place the exuvia in a rigid container (when 35mm film was so commonly used, the plastic film cans were excellent collecting containers), such as a plastic pill vial, film can, mints tin, etc. Label it with your field number (see the page on submitting vouchers -- the documentation and submission procedure is the same). When we receive the collected exuviae, they are immersed in ethanol and placed into glass vials, labeled, and identified. All that information is recorded into our database. Variation in emergence sites says something about the behavior of the adults and when they emerge, and recording this information is very useful.

Odonata exuviae are identified the same way as preserved nymphs. We keep the exuviae in ethanol so as to keep the exoskeleton flexible and so the bits don't break off, which they would if dry. There is no all-around published guide to immature Odonata, and the best resource thus far is the still-incomplete Michigan key by Ethan Bright. It is a few years out-of-date on the distribution maps, and species found in the state, but it it still the best resource available, and is very useful.

You will usually find clubtail exuviae very close to the water's edge, often on rocks, bridge abutments, or debris. Basket-tails (Epitheca spp.) and many skimmers usually emerge in vegetation near the edge of water, often on shrubs or emergent reeds. Darners often emerge on cattails and similar plants a few inches above the water. However, you may find river cruisers and stream cruisers have emerged many yards from the water, up on the side of a structure or tree trunk. Damselfly exuviae can also be identified, but are not as robust as dragonfly exuviae, and are often missing the caudal lamellae, which are important for identification. If you are a keen observer, you can record the number of exuviae along a stretch of river or stream, which will often be useful in estimating the size of the emergence of a particular species. Exuviae surveys are often done in other states, and are used as a monitoring tool.

It is not uncommon to see adults emerging from the nympal stage. It's an amazing process that often takes just a few minutes. Of course, the adults are easier to identify than the nymphs, but photographing the adults and keeping the exuviae for vouchers is an acceptable compromise. In general, it's not recommended to collect adults immediately after they have emerged, as their bodies are too soft and lack the coloration necessary for identification. They will shrivel up to thin ghosts of themelsves. If you wish to collect them, please place the living specimen into a container large enough and rigid enough to allow them to complete their transformation into a more mature specimen. This usually requires about 4 to 8 hours for them to fully harden and not be what are called "tenerals." Then, photograph them if you wish, prepare them as specimens, or release them.