Ultrasound pest control devices
Do electric insect repellers example work?
For context, I live in a rented house that has several of these installed. My personal observation is that they do nothing to repel bugs, but actually are effective at killing the bugs that enter the home — it just might take a day or two for the bug to die first. However, my personal observation may not be a typical result, hence the question: do these devices work? If it's a case of, "Yes... but", what do you need to look for to get an effective system?