The Twelve Spotted Skimmer Dragonfly is a fairly large dragonfly with a length of up to 6 cm. Each wing is marked with three dark spots, one near the base where it attaches to the body, one in the center that nearly spans the width of the wing and one at the tip.
Females and immature males are brownish-black. The side of the thorax is marked with two diagonal yellow stripes, and each side of the abdomen is lined with yellow.
Mature males are brownish-black, faintly marked with yellow, and become blue on the top of the abdomen. They may also develop a whitish patch on each wing to the outside of the spot next to the body.
This species is found from British Columbia south to California and all the BC Coastal Regions. This dragonfly can be found around lakes, ponds, and marshes, particularly those with exposed shorelines.
Males establish and defend territories, and can be very aggressive towards members of their own species as well as other dragonflies. After mating, the female flies off alone, to lay her eggs.
The larvae are fairly large with a length of up to 3 cm. It is dark orange-brown in colour, and the abdomen is rounded. There is a small hook on the top of abdominal segments four through seven, and there is a thin, slightly curved, rear-facing spine on each side of abdominal segments eight and nine. Larvae live in the debris on the bottom of lakes, ponds, and marshes.
Adults generally fly from early June through August. They perch on rocks and branches to hunt. These are easy guys to photograph, they like to perch. They look quite similar to the Common Whitetail Dragonflies.