As the Dot-Tailed Whiteface matures, all the yellow on its body disappears except for the spot nearest the tail. This single spot makes it easy to distinguish from other Minnesota dragonflies even at a distance. A juvenile female. Parasitic mites can be seen on her abdomen. 925x1200 Males and females have similar markings both as juveniles and adults.
Females have two terminal appendages, which are much shorter than the males'.
The shape of these appendages varies among species, but you can sex any dragonfly by the number of appendages if you can get a close enough look. Carver Park Reserve and Itasca State Park have large populations. I've also seen them at Elm Creek Park Reserve and near the boat dock at Lake Maria State Park.