Gerridae

May to September

Korea, Japan, China, Taiwan and Russia

Males and females are around 9~10- and 11~12-millimeter-long respectively. They have brown body in a dark brown or black ground, and have dense silvery fine fur. Antennas are thin and very short. There exist both long- and short-wing types. When it comes to the long-wing type, the membrane reaches to the end of the abdomen. Femurs of the fore legs are straight and a little thick in the middle. Femurs of middle and hind legs are long and well-developed, which is similar in length to the body.

They inhabit in relatively still water such as the river or reservoir, and suck out body fluids from other insects.