You can buy ultrasonic pest repellents for every pest you could think of. Mole repellents for gardens, rodent repellents for the loft and insect repellents for the kitchen.
You will find them in every garden centre and DIY store in the country, as well as all the major online market places. You may think that as they are available at such a large number of retailers that they must work....
No they don't.... "Well you would say that your a pest controller" your probably thinking. True but if they did I would save a fortune on pest control training, Insecticides, traps and rodenticides My job would be so simple I could simply arrive at my customers home plug in the ultrasonic device collect payment and on to my next job. I could even provide a rental service that would be a great business idea, probably a very short term one as trading standards would soon be on the case.
I see these devices every week in some cases the customer has learned the hard way that they don't work. Often spending more on the device than they then pay a professional to resolve the pest issue. I'm sure there must be some science behind these ultrasonic devices but I have not seen any evidence that they make a pests regardless of species vacate your home or garden.
Preventing pests getting established in the first place is always the best option. Denying them food and harbourage will keep the majority of pests away. If you do find that you have unwanted insect or rodent visitors the best option would be to employ a professional pest control company.