Collecting Specimens

What to Sample

Dragonflies and damselflies spend most of their lives as larvae living under water in a variety of aquatic habitats. When ready to mature, they crawl out onto land and emerge from their larval skins (called exuviae) as young adults (called tenerals). This survey samples mature adults, larvae, and exuviae, all of which are at least potentially identifiable to species. Tenerals are soft-bodied, fly weakly, and do not develop full adult coloration until at least a few days after emergence. For this reason, and because they do not preserve well, collecting of tenerals should be minimized. However, the presence of tenerals is important to note because they indicate a breeding site, and their appearance marks the time of emergence of the species.

A rule of thumb is to sample whatever life stage is available, preferring mature adults (easiest to identify) and exuviae if they are present. In some circumstances we may ask you to focus on just one life stage. For example, some clubtails (Gomphidae) are infrequently seen as adults because they have short flight periods and spend much of their short adult life foraging high off the ground or perched in trees. Thus, these species are best sampled as larvae or exuviae. Exuviae have the advantage over adults of firmly indicating a breeding site; adults could have flown to a site from elsewhere. Identification of exuviae can be easier than for larvae because exuviae represent the final and most mature molt of the larval stage where the key larval characters needed for identification are fully developed. Larvae could be at any stage of development, and if only partly grown, may not show the key characters needed for their identification. However, larvae are still very useful and are available over a wider time frame than the other stages. Some people raise nymphs to adulthood for positive identification.

Males are often more conspicuous than females, and you are likely to encounter many more males than females. In some species, females are very reclusive and are rarely seen. Collecting mostly males is acceptable because they are usually, but certainly not always, easier to identify. Both genders are useful in collections. As you gain experience, we may ask you to focus on one gender or the other with different groups of Odonata. Back to the top

How Many to Sample

With mature adults of those species for which specimens are necessary, try to collect a few (two or three) specimens of each. Please note that within some genera, the species are closely related and look very similar. To further complicate the picture, males and females usually differ in appearance, as do tenerals and mature adults. When you learn to identify tenerals, note their occurrence but avoid collecting them unless you have a specific purpose for doing so. When collecting exuviae, an ideal method is to collect all of the exuviae along a measured distance of shoreline, looking from the water’s edge to several feet up the bank. Note that exuviae could be on the ground or attached to stems of vegetation from an inch or two to quite a few feet above the ground. Back to the top

When to Sample

June and July are "prime time" for Odonates, so your most intense efforts should be concentrated then. However, some species fly later in the summer and fall, often well into October. May is an important month as well, because some species, including some of our rarest ones, have short, early flight periods. A few migratory species arrive in Minnesota as early as mid-April. Regarding time of day, the greatest diversity can often be attained during sunny, warm afternoons. However, some species are most active at other times, so the best time to sample could depend on the species you are looking for. Avoid sampling during inclement weather, as most species perch in trees or other vegetation then and are difficult to find. When collecting exuviae, time your searches to the known emergence periods of the species of interest because exuviae persist only briefly (a week or two) before wind and high water levels displace them. Mid-May through early June is a crucial time frame for collecting clubtail exuviae along rivers and emerald exuviae in bogs. An excellent goal for cooperators is to thoroughly document the diversity of dragonflies and damselflies at one or a few sites near their home. To do so, visit the site at 10-day to two-week intervals during the entire flight period (late April through October). Back to the top

Where to Sample

Minnesota has the distinction of being one of the most unstudied states when it comes to Odonates. We have counties with few records of dragonflies or damselflies. Surely, more Odonates live in those counties, but no one has recorded any data from them. Since one of the missions of the MDS is to fill in the distributions of these insects, you are highly encouraged to spend some serious time and effort in those regions.

Other habitats of interest include spring seeps; ephemeral ponds (vernal pools); large rivers; small streams that run through bogs/fens; wooded swamps; acid bog ponds and wetlands with sphagnum mosses; and alkaline wetlands. These areas hold species we need to learn more about, and, due to the difficulty in entering some of these habitats, they have not been as well sampled as some other habitats. Feel free to contact us for help in finding promising areas to sample close to where you live. Presence of sphagnum mosses, in floating mats or with scattered, fishless pools in sedge meadows, are good indicators for a number of rare species of emeralds (Corduliidae). In lakes, diverse shoreline vegetation often provides habitat for many species of Odonata. Some species have very specific habitat requirements, whereas others can be found just about anywhere. Aquatic systems differ in a variety of ways including: waterbody size, water chemistry, presence or absence of sunfishes, and types of emergent and submergent vegetation. Moreover, at any aquatic site there will be a variety of smaller habitat areas that differ subtly from others in shading, shelter from wind, and types of vegetation. So, try to check all habitats present at any site you visit.

Always ask permission before collecting on private lands. Many public lands do not require a special permit, but please check before collecting on those lands. Scientific and Natural Areas (SNA), USFWS preserves, MN State Parks and some other publicly managed lands require a permit before collecting. ASK FIRST! Inour experience, the managers of these lands are usually very open to scientific work being conducted on their lands but permission must be obtained, first. Back to the top

How to Sample

As you gain experience you can record the presence of those species that you are sure you can identify in the field, and can begin to collect two or three specimens of those species that you can’t identify, especially those you think might be unusual. Feel free to send us specimens or post photos on our Facebook page to confirm your identifications. Look for subtle differences among species in sizes, shapes, colors, wing patterns, and habits, and visit all the different habitats at a site. Be aware also that species differ in their behaviors, and that these behaviors can vary with time of day and season. Many species fly boldly in plain view, but some are secretive and require patient observation to be located. Sometimes you may be looking for a certain species or group of species at specific sites that I or others have directed you to. Do not collect a species that you know is federally listed as threatened or endangered.

Net dragonflies in flight by swinging at them from behind. Many species will fly a predictable route, so you can watch a while to see the pattern and then set up an ambush at a convenient spot, perhaps where you are partially hidden by a tree or shrub. When perched, approach them with very slow movements. Once in the net, remove the specimen by hand (they don’t bite very hard). Place the dragonfly by itself, wings held back together, in a glassine or paper envelope along with a date and location label. Close the envelope with a paper clip. Put the envelope into a checkbook box or other similar container. Back to the top

About Labels

Every biology student is taught that the label is more important than the specimen. Believe it - a specimen with no label is basically worthless. There is nothing more frustrating than having a rare specimen and having no idea where it was collected. Information that must be included on the label is the date, the location, and your name. Locations should be as precise as possible and should include not just the name of the lake or stream, but the exact location on it. For example, if you collect a certain species only at a sphagnum-bordered cove at the southeast corner of a lake, then say so. If you visit a lake but stay within a few hundred feet of a public boat ramp, please say so. If you visit an unnamed wetland, pond or stream you should give a physical description (e.g. 200 meters NE of the intersection of Bellwood and After Hours roads). The bottom line is that if you find a rare species, you want someone else to be able to read your label and find the spot where you caught it. If you have a GPS unit, include the exact coordinates (latitude and longitude in decimal degrees and datum if known). Please use pencil because pencil marks don’t run when wet or when exposed to acetone. Write directly on the envelope or place a label inside the envelope or jar, not clipped or taped to the outside where they could fall off.

Click here to download a Specimen Label Template (21 KB pdf). Please print specimen labels from the template document on 65-pound acid-free card stock (like Wausau Bright White Premium Card Stock), available at office supply stores. Write your data on each label in pencil. Back to the top

Dragonfly 101 Dragonfly Biology Dragonfly Behavior Dragonfly Life Cycle Surveying Species of Interest Collecting Specimens Preserving Specimens

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