In the Harry potter series do you need a wand to apparate/ disaparate?

I was reading the Harry potter books and I've noticed bits like "Ron was now trying to apparate without a wand" and I was thinking if that is the case that must be why lily and James potter didnt aparate with Harry when voldemort was on his way but in the Harry potter and the deathly hallows part one film I noticed there was no wand in hermioneies hands when she apparated Ron harry and herself out of there, does anybody know?