The nymphs are sprawling forms with bodies, legs and head that are strongly flattened. The head is large in relation to the body. Eyes are also large and are located on the dorsal surface of the head. Gills are present on abdominal segments 1 to 7. Adults have two tails and five freely moveable joints in the hind tarsus. Two pairs of cubital intercalary veins are present in the fore wings, while both fore and hind wings display heavy veination. The males have large spherical eyes that are normally light in coloration during the day and black at night.
The nymphs of this genus are the only ones in the family that possess enlarged gill plates, which extend under the body to form a suctionlike device. Adults tend to be dark brown or reddish-brown in color and have cross-veins in the stigmatic area of the wing that are interjoined into a network.