Dr. Samuel Ramsey showed this feeding on adults as well as on bee larvae in the capped stage and presented his research in the youtube presentation: Varroa feed on Fat Body - lecture at the INIB honey show 2019
This means that Varroa do not have a "phoretic stage" when they are attached to adult honey bees because a phoretic stage does not include feeding on the host used as transportation. Instead, Varroa's time spent on adult bees is properly called "dispersal phase or stage."