The following is a basic preservation procedure for adult odonates: After collecting an odonate in the field,
place it into a glassine envelope, close the envelope with a paper clip and attach a date/location label.
To place it in the envelope, fold the dragonfly’s wings together over the back and slip it on its side into
the envelope. Put the envelope into a sandwich-type plastic container (or checkbook box) for the duration of
the field outing along with any other specimens collected that day. Unless it is very hot, they will stay alive
for hours (even days) and will pass through all the food waste from their gut, which allows them to preserve
When back from the field, clip the tips of the corners off the envelopes with scissors to allow
the preservative in quickly. Submerge the dragonflies in a container of acetone while still in the envelopes.
Use an easy to seal, wide-mouth Tupperware or Rubbermaid-type container that is just big enough to hold the
sizes of envelopes being used. Acetone is preferred because it does a fairly good job of preserving colors,
which can be important in identification. Soak the specimens for at least 8 hours (overnight is fine). When
it is time to dry them, working in a well-ventilated area, remove all the envelopes from the acetone jar using
long forceps to limit skin contact. Allow them to drip-dry for 30 to 60 minutes. Small racks can be made or
purchased for this purpose (like small dish drying racks). Then carefully remove the specimens from the envelopes
with soft forceps and lay them on cardboard for a few hours to thoroughly air-dry. Dermestid beetle pests can
get to and destroy recently acetoned dragonflies, so be careful not to leave specimens out in the open to dry
for more than a few hours.
The last step is to put the dry specimens into a polyethylene baggie. Then slide that and a 3"x5" card on
which the date/location information is written into a permanent, clear, polypropylene envelopes. This double-
bagging technique helps insure the specimen will not be damaged during subsequent removal. Fold over the end of
the clear envelope and seal with a paper clip. Finish by putting all of your specimens into a shoe box or similar
container with a few moth balls.
In a pinch you can also temporarily freeze specimens, for example to accumulate a larger amount
of specimens over time and then go through the acetone routine less frequently. However, freezing is less
desirable because when thawed out, the specimens will decompose rapidly and colors are invariably lost.
Acetone removes the lipids from the specimens and turns yellow after considerable use. You
can discard old, yellowed acetone by throwing it on an asphalt surface on a hot day and it will vaporize
almost immediately. The envelopes with the clipped corners may be reused.
Nymphs and exuviae are best preserved in 70-80% ethanol and placed in vials or small jars, with date/location
labels inside the jars. Isopropyl alcohol (rubbing alcohol) is easily purchased at any drug store and can be
substituted for ethanol. Exuviae do not absolutely need to be placed in a liquid preservative and can be stored
dry. However, they are more vulnerable to breakage when dry and are much more difficult to examine under a
Labels are a crucial part of a collection. A specimen with no label is basically worthless. If you find a rare
species, you want someone else to be able to read your label and find the spot where you caught or observed it.
To that end, information that must be on the label includes the date, the location, and your name.
It is always best to include the exact coordinates (latitude and longitude) as well as a narrative
description for locations. Latitude and longitude can be marked in the field if you have a GPS unit or mapping app
on your phone, or obtained afterwards with a website like Google Maps. Location descriptions 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,
"a sphagnum-bordered cove at the southeast corner of Clear Lake", or "a few hundred feet west of the public boat
ramp on Mud Lake". Be especially descriptive if you visit an unnamed wetland, pond or stream. Use pencil because
ink can smear when wet. Place labels inside the envelope or jar of collected specimens, not clipped or taped
to the outside where they could fall off.