What to Survey
The goal of surveying should be to gain as complete a picture as possible of the species that
occur at a site. Depending on season, one or more life stages may be present (nymphs, exuviae, or adults).
A rule of thumb is to sample whatever life stage is available, preferring mature adults, if they are
present, because they are the easiest to identify. However, some species are infrequently seen as
adults and are best sampled as nymphs or exuviae.
Dragonflies and damselflies spend most of their lives as nymphs living under water in a variety of
aquatic habitats. Nymphs could be at any stage of development, and if only partly grown, may not show
the key characteristics needed for their identification. However, nymphs are extremely useful,
especially when mature, and are available over a wider time frame than the other stages.
When nymphs are ready to mature, they crawl out onto land and emerge from their nymphal
skins, or exuviae. Exuviae have the advantage over adults of firmly indicating a breeding site; adults
could have flown to a site from a considerable distance. Identification of exuviae can be easier than for
nymphs because exuviae represent the final and most mature molt of the nymph stage where the key
characteristics needed for identification are fully developed.
After nymphs emerge as young adults they are called tenerals. Tenerals are soft-bodied, fly weakly, and do
not develop full adult coloration until at least a few hours or 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 their presence indicates a nearby breeding site, and their
appearance marks the time of emergence of the species.
Mature adults are the easiest to identify, making them the most common life stage surveyed. Of these, males are
often more conspicuous than females and usually, but certainly not always, easier to identify. You are likely to
encounter many more males than females. In some species, females are very reclusive and are rarely seen. However,
the ability to identify both genders is useful.