Ultrasonic gizmo's have been proven to do nothing..
Proven by whom?
Have you tried them, or is this something you read? My guess is, the latter.
I have consistently said I am not sure how well the lower powered ones in the US will work. But, I have personally tried them here, for some years now, and they do work.
I am not going to dig out the paperwork right now, to look up the manufacturer. They are built like a little speaker, 3 or 4 inches on a side, and the specs said they are 1.5 watts. If you hit the test button, it drops the frequency into the audible range, and it is loud, like a squeal.
One day several years ago, our builder was in the house doing something, and I was sitting by the door reading. A lizard went running across the floor very fast and a few feet in front of the ultrasonic, he froze. I said, "Hey, Virgilio, look at this."
He came over and said, "That is a poisonous one."
I walked over, took my shoe off, and converted him to room temperature. He never moved a muscle, which is very unlizard like.
Virgilio said, "One day when you were gone, I found a dead one in that same place."
Our scorpion count went from a couple a month to none for months at a time, but my wife finds them in the yard all the time. And, when we do find one, it is hidden near the old door under the boxes of storage my wife puts there. (A door hundreds of years old my wife salvaged from her ancient family home, and we had it built into the house. It has those big nail heads like you see on Mexican cathedrals, but is not in great shape, so anything can walk in under it.)
When we started living here, we had 'mouse tracks' all over the house, and they built a nest in my underwear drawer. Since we put in the ultrasonics, we have seen two mice in the last several years, and one of them was dead. It had apparently sought refuge under a block, because when I moved the block there it was.
Now that I think of it, in our trailer in McAllen, we had a lot of mice coming in. We put in the light ultrasonics from HD, and it seemed to help some, it's hard to be sure, because I also put hardware cloth around all the pipe entries. So, I can't be sure, but here in Mexico I am sure, and so would you be if you lived here.