An intermittent insect trap, working time of which proceeds by alternating periods, and embodies two primary operations including actuation of ultrasonic waves to excite an attractant and form a mist and formation of a backpressure airflow, thereby ensuring that concentration of the mist is not disturbed and thus reduced by external forces during the course of vaporization, and thus preventing dilution of the attractant. Moreover, intermittent operation of a motor results in substantial savings in power. The insect trap primarily uses a mist excitation device to excite and disperse an insect attractant as attractant particles that suspend in the air and diffuse. After achieving a predetermined diffusion concentration, operation switches over to actuate a backpressure device, which pressures lured insects into a receiving chamber through a valve. The alternating working times and mechanical ensnaring of insects provide the insect trap with effective inducement and power saving features.