Nepidae

April to October

Korea, Japan, China and Taiwan

It is around 30~38mm-millimeter-long (except tracheal loop). It has yellowish brown, grayish brown or dark brown body. The entire body is flat and its head is quite small. The antennas are short and small, and hidden behind compound eyes, which are not seen from the back. Forelegs look like a sickle, which is useful for hunting for food. Middle and hind legs are used for swimming. There is a pair of breathing tubes at the end of abdomen, which is very long as much as the body length.

They inhabit in the still water such as stream or reservoir. When they need to breathe, they come to the surface and get their trachea out of the water. They live on secretion from small fish or tadpoles.