If this is a recurring problem it's time to think about the acoustics of your space. Persistent infestations of musicians are often traceable too much (or too little!) reverb. Large open spaces attract the bands, insulated surfaces attract indie rock groups, often looking to found their first album. Kill one member and they will be replaced, and commemorative albums will be released. If you see completion albums? Just give up.
@futurebird @JuliusGoat You could also consider the economics of the area. While there are musicians who are immune, driving up property values can help deter the band from fully forming.
If nothing else works, consider a major construction project. They hate the noise. You will, too, but it might be preferable to a marching band.
And remember, we're rooting for you. We're all in this together.