Abstract: The paper reports firstly that the predatory insect, the ground beetle C. virgulifer, fed on young farmland mouse indoors.The young mouse was hurt by one or two adults of the predator,and killed by three or moue of them.An average intake of per predator was 0.21g.The accumulative time from attacked to killed of the young mouse was taken two hours and thirty-eight minutes.Attacking behavior of the predator was several predators fed altermately the young mouse at one place and made it death by excessive lose of blood.