Canada darner (Aeshna canadensis) is a large mosaic darner. It occurs across the northern United States and southern Canada. It is the most common blue darner in Minnesota, where it occurs throughout the state except for the western prairie counties. It is a late-season dragonfly, not appearing until late June and flying to the end of September.
Adults are about 2¾″ long. The body is dark brown with blue, green, or yellow markings that darken in cool temperatures. Males always have mostly blue markings. Females have three color forms; blue, green, and yellow. Most females are green form. Blue form females are rare.
There are at least ten blue darner dragonfly species found in Minnesota and they are difficult to tell apart. Canada darner is most easily distinguished by the lateral stripes on the thorax. The front stripe is deeply notched, is narrowed toward the top, and has a narrow rearward extension (flag) at the top. The rear lateral stripe is not notched. Like all mosaic dragonflies, there is a black T-shaped spot on the upper part of the face just below where the eyes meet. This is best seen when viewed from above. There is no bold black horizontal stripe across the middle of the face.