His feuds with Madonna and Paris Hilton will have to wait ... 'cause DeadMau5 is waging a brand new war -- with the "dumbasses" who ransacked his mother's home. 

The DJ behind "Ghosts n' Stuff" and "Raise Your Weapon" went to Facebook last night and explained, "wow. a couple of dumbasses in Niagara Falls broke into my mothers house, ransacked it, slashed her paintings and stole a TV / sonos stuff... etc and basically trashed the house."

He continued, "man, you a**holes picked the wrong house ... mau5 is gunna find you."

Fortunately, the DJ says his mother is fine -- she wasn't at the house at the time of the burglary.