Do sub panels need to have a bonding strape?

it depends on the Sub-panel. If the panel had two ground/neutral bars connected together (because it came as a main panel) and then the bars are seperated to allow the grounds to go to one bar and the neutrals to go to the other then the ground bar would need to be bonded to the box—usually by strap or screw.

I agree with Charles and:
Its a good idea to always indicate what the bonding issue or question is.
Bonding is just the proper way to join two metal parts. It depends on the specifics. There are small straps for bonding panels and there are long straps to bond the neutral bus to the ground bus in service equipment.

Lots of old messages/threads that went on forever just because of terminology mixups on the old board.