dust bunny 
noun North American informal
A ball of dust and fluff.Everything in the Purdue laboratory, including the occasional dust bunny and 6000 individually wrapped half-pint glass milk bottles, had been carefully packed for the move to Washington University....
- My stupid brainless cat that doesn't know a mouse from a dust bunny.
- The concrete steps didn't look too bad when I started, but by the time I was done, my dustpan held a dust bunny that was truly frightening.