The damselfly Chalcolestes viridis, commonly named willow emerald damselfly or green emerald damselfly, has a metallic green body and large pale colored wing spots (pterostigma) with a visible black border. This species has a body length of 4 to 5 cm and a hindwing span of up to 5 cm. At rest, this damselfly holds its wings open at 45°, away from its body.
The willow emerald damselfly resides in areas of still water with overhanging trees. Females oviposit into twigs of willow or alder, overhanging water. Eggs then hatch the following spring, the larvae falling into the water below where they complete their development.