The distribution of various groups and species of Odonata is highly variable. Some genera and species are widespread while others are highly local in their distribution. Some families are restricted to cool streams or rivers, others to ponds or still clear waters, and some to marshy places. The presence of dragonflies and damselflies may be taken as an indication of good ecosystem quality. The greatest numbers of species are found at sites that offer a wide variety of microhabitats, though dragonflies tend to be much more sensitive to pollution than are damselflies.
Many ecological factors affect the distribution of larvae.
The acidity of the water, the amount and type of aquatic vegetation, the temperature, and whether the water is stationary or flowing all affect the distribution of Odonata larvae. Some species can tolerate a broad range of conditions while others are very sensitive to their environment. For lots of information and links about Odonata, try the Oregon Dragonfly and Damselfly Survey , Blair Nikula's dragonfly and damselfly links , or the Odonatology homepage . Or you might prefer to view picture galleries at the more modest Dragonfly website or these Odonata Photograph Archive from the University of Michigan Museum of Zoology . For more on the systematics of dragonflies, damselflies, and their extinct relatives, visit the Tree of Life project at the University of Arizona.