Donacia

Donacia is a large genus of aquatic leaf beetles in the subfamily Donaciinae. Like other members of that subfamily, the beetles have densely pubescent undersides and long antennae. The genus is recognized by the truncate elytral apex and pubescent area above the procoxa. Adults are active and readily take flight. Adults feed on the upper epidermis of host plants; some may be pollen feeders. Larvae feed on the sap of submerged portions of aquatic plants, such as water lilies, sedges (Cyperaceae), Sagittaria (Alismataceae), Sparganium (Typhaceae), pond weed (Potamogeton). They are believed to breathe oxygen from plant vessels as well as cutaneously. Adults live on surface parts of the same plants but can go under water for extended periods because of their plastron.

There are 15 proposed subgenera. The three largest subgenera are: Donacia (Donacia) s. str., with 10 Nearctic and 5 Palaearctic species; Donacia (Cyphogaster) with about 6 Australasian species; and Donacia (Donacocia) containing about 21 Nearctic species and about 75 Palaearctic species.