Disclosed is an ultrasonic pest deterrent device adapted for use in greenhouses and gardens, comprising a printed circuit board, output signal transducer and a housing adapted to shroud the components of the assembly within its waterproof interior. The device comprises a ramp signal generator and voltage control oscillator adapted to sweep between a chosen set of switchable frequency pitch ranges and tones, a sweep stop for single tone testing, a confidence test button, a power switch and indicator light. The confident test button provides an audible tone within human hearing range to ensure the device is operational, while the power indicator light provides a visual means of verifying operation when the device is emitting signals in the ultrasonic range. A timing circuit disables or modulates the device from continuous operation, saving battery life and randomizing the output signal for increased pest annoyance and deterrence.