Damselflies and Dragonflies are both members of the order Odonata, with 407 species in North America. Both are often brightly-colored with large heads, compound eyes, two pairs of translucent wings with many veins, and long abdomens. To tell a dragonfly from a damselfly, look at the way they hold their wings: When resting, a damselfly holds its wings together, close to its body or slightly above its body (an I-shaped silhouette). A dragonfly holds its wings outstretched, away from its body (a T-shaped silhouette).
Dragonflies go through three life phases — egg, larvae and adult. Adult dragonflies are sometimes called “mosquito hawks”, because they feed on mosquitoes. They also feed on large horseflies and other insects. To reproduce, adults mate and lay their eggs directly into the water. The eggs hatch into larvae, which are aquatic and use gills to filter oxygen from the water. As they grow, most dragonfly larvae shed their skin 11-12 times, feeding on other underwater invertebrates and even small fish. To molt to their adult form, mature larvae climb out of the water onto rocks or tree roots, shedding their skin one final time. Adult dragonflies live for about a month, on average, however every species is different. Some species take 2 years or more to complete a life cycle.
Kondratieff, Boris C. (coordinator). 2000. Dragonflies and Damselflies (Odonata) of the United States. Jamestown, ND: Northern Prairie Wildlife Research Center Online. Version 12DEC2003.
Voshell, J.R. 2002. A Guide to Common Freshwater Invertebrates of North America. Blacksburg, VA: McDonald & Woodward Publishing Company.