Abstract: A method and a device for automatically detecting and signaling the presence of prey caught in a trap. The trap has inlet ports equipped with a one-way inlet mechanism such that once a rodent has passed a central point the rodent is contained within the trap. After the rodent has passed the central point, the trap is reset to the start position in order to attract additional prey. The trap is provided with a device for signaling the presence of vermin in the trap. The mechanism may be operable via a push button operated by movement of the vermin. Alternatively, means for detecting the rodent may include the use of vertical or horizontally elongated elements that are actuated by the movement of the vermin. A further embodiment includes a photocell, or a sensor, to indicate the presence of rodents. The mechanism for signaling may include lights or sound devices that can be secured to the trap or remotely activated via wired or wireless means.