The Shadow Darner Dragonfly is a large dragonfly with a length of up to 8 cm. The base color is brownish-black. The top of the thorax is marked with two pairs of greenish crescent-shaped spots. Each side of the thorax is marked with two yellow to yellow-green diagonal stripes. The abdomen is marked with bluish-green spots. The male has paddle-shaped anal appendages. These are quite beautiful to observe in the wild, sounding almost like mini helicopters flying overhead.
This species is found from the Yukon Territories south to California and can be found in all of the Pacific Northwest. This dragonfly can be found near ditches, slow streams, and ponds. Males establish territories along the shores of slow streams, marshes, and ponds. After mating, the female flies off alone to lay their eggs on the leaves of aquatic plants.
The larvae are large, with a length up to 5 cm. It is long and slender, the typical shape of immature Darners. It is mottled green and brown. The larvae are active predators and are able to swim by squirting water out from the ends of their abdomens.
They generally take several years to mature before changing into a dragonfly, they do this at night. Adults generally fly from late April to November and do all of their hunting while on the wing. Adult shadow darners are able to regulate their body temperature which enables them to fly in temperatures too cold for most dragonflies.
This species can tolerate freezing temperatures. This is how it does so well living in the Yukon Territory, there can be summer frosts at any time. Not many others can do this.