Black-winged Damselfly

Close-up of head of black-winged damselfly photographed near Minnehaha Falls (several miles south of Augsburg College), on June 10, 2002

The jaws and large bulging eyes of damselflies such as the one shown above are some of the last things seen by many a small insect, since damselflies, like their cousins the dragonflies, are highly predaceous. Indeed, not only are the adults of damselflies and dragonflies predators, but so are the aquatic immature stages, which have impressive hinged “jaws” (this structure is actually called the labium) that reach out quickly to strike and capture small aquatic insects, crustaceans, fish, and other aquatic animals.

Dragonflies keep their wings spread all the time

Though they are both members of the insect order Odonata, damselflies differ from dragonflies in several respects. As adults, damselflies are generally smaller and more slender than most dragonflies, and while dragonflies hold their wings outstretched even at rest, damselflies fold them back while at rest. Dragonflies are also usually faster, more powerful, and more acrobatic fliers, and are expert at capturing flying insect from the air.

Damselflies fold their wings back when resting

Damselflies and dragonflies also differ as nymphs. While nymphs of both are aquatic predators, damselflies have three leaf-like appendages at the tips of their abdomens that function as gills, but dragonflies have internal gills and breathe by pumping water in and out of their abdomens via an opening at the end of the abdomen (for photos of each of these general nymph body types, see http://insects.ummz.lsa.umich.edu/michodo/test/Subordrs.htm ).

Nymphs of both generally spend most of their time sitting still or walking about (often seeking both prey and refuge on underwater vegetation), but both also have means of rapid escape when faced with danger. In the case of damselflies, the nymphs can swim by thrashing their bodies back and forth, using their gills to propel them similar to how fish use their tails. Dragonfly nymphs, on the other hand, are jet-propelled when faced with a dangerous situation. When they need to get away fast, they contract their abdomens rapidly, squirting water out of the opening at the end of the abdomen, which shoots them through the water.

Diagram of a damselfly nymph, showing the leaf-like gills.
Source of diagram: http://biodidac.bio.uottawa.ca/

The various damselfly and dragonfly families are quite diverse in habits and appearance. The black-winged damselflies shown here are members of the family Calopterygidae, a family that contains some particularly attractive species. Some members of this family have clear wings, which is typical of most damselflies, but as can be seen in these photos, some others have have wings that are quite striking in appearance. The black wings of the species shown here give these damselflies a very fluttery appearance when in flight.

For most insects, definitive identification to the species level requires expert knowledge of the group of insects in question, and I am no expert in damselfly identification. However, the damselflies pictured here are similar if not identical to what other on the web have called Calopteryx maculata, so this might well be the species in my photos.

Whereas some damselflies and dragonflies live near ponds or lakes (which are the bodies of water where the nymphs of those species live), the black-winged damselflies pictured here are usually found around streams since their nymphs are stream dwellers. On the day these photos were taken, these damselflies were quite conspicuous in the wooded area along Minnehaha Creek, between Minnehaha Falls and the Mississippi River. In some spots there were aggregations of 5 to 10 individuals resting in a single streamside bush or tree. Dragonflies and damselflies have very interesting mating behavior, and some show very strong territoriality.

Additional Links

Additional general information on the family Calopterygidae can be found at:

http://insects.ummz.lsa.umich.edu/michodo/test/Caloptx.htm

A terrific introduction to the dragonflies and damselflies can be found at

http://www.ucmp.berkeley.edu/arthropoda/uniramia/odonatoida.html