Mosquito?
https://www.cbsnews.com/news/mosquito-repels-youths/
The latest generation is apparently tunable so you it may also be able to use it to disperse flocks of snowbirds. (Earplugs may be required...)
(But of course, by now the yoofs have subverted it and use it as an adult proof ringtone.)
The sound, Roth explains, is supposed to work as a repellant for a simple reason: Most people over 30 can't hear it, most people under 20 can, and hate it.
The latest generation is apparently tunable so you it may also be able to use it to disperse flocks of snowbirds. (Earplugs may be required...)
(But of course, by now the yoofs have subverted it and use it as an adult proof ringtone.)