Sometimes
In Canada there is no requirement to wear a parachute when doing aerobatics, passenger or not. However when I have a passenger we always wear them. Why? Because most of my aeros are solo, and the rear passenger changes the way the aircraft will potentially react to inputs, and could react in a way I am not familiar with. So far not a problem but.......
Also, I have this sense that with two aboard the stresses on the aircraft are greater, or at least different.
When solo I wear one when I am planning to do some maneuver(s) I am not totally familiar/comfortable with. Otherwise the chute stays home.
I just had my prop overhauled and will definitely wear a chute for the first flight after the overhaul.