How long does it take for an ultrasonic insect repellent to work?

It takes about 4 weeks for an ultrasonic repeller to successfully repel pests.
In the first to two weeks, users may find that the pests are more active than not using the devices. This is because the ultrasonic and electromagnetic waves emitted by the devices begin to attack pests’ auditory system, sensory nerves, central nervous system, and reproductive system, making them very uncomfortable , loss of appetite, irritability, they become more active.

In the third week, the pests become listless, their reproductive ability decrease, and they do not want to move, so they are not so active.
In the fourth week, the pests could not tolerate the ultrasonic waves, thus escaping from the range of the devices, and the users find that the number of pests decrease significantly.
In order to achieve the effect of long-term insect repellent, it is recommended that users insist on using ultrasonic insect repellent equipment.
In addition, if the fixed-frequency ultrasonic insect repeller has been used for a long time, the insects will adapt to this frequency, and the equipment will no longer have an effect on them. Therefore, the frequency conversion is more effective. By changing the frequency continuously and irregularly, the insects are continuously attacked, so as to achieve the effect of long-term insect repellent.