Large, swift-flying dragonflies, usually marked with blue, green or yellow. Adults hunt tirelessly for insects over ponds, lakes and streams, and wander widely in search of prey. Most species rest in a vertical position, but a few sit flat on the ground. Females have a prominent ovipositor and lay eggs in water plants or floating wood above or below the water line. Larvae are slender and sleek, with flat labia lacking bristles; they are rapacious hunters among water plants. Recently, A. californica and A. multicolor have been transferred from Aeshna to Rhionaeschna.
An uncommon dragonfly of peatland pools and peat-margined lakes. Unlike most mosaic darners, females patrol like males and often lay eggs in vegetation above the waterline. Presumably, this behaviour reduces the amount of attention that males give them, allowing more time for uninterrupted egg-laying.