In the Chiricahua Mnts there are two recorded species of manzanita: Arctostaphylos pringlei and A. pungens. It's likely the latter here, as the former has glandular hairs on the pedicels which I think would be apparent in the photo (cf. pg. 2 here).

The leaf also has a tiny "point" at the tip (a la "pungens"...though I think pringlei can have such too).

Looks like bumble and/or carpenter bees had already bitten holes and practiced "nectar thievery" on some of the flowers, as they so often do to manzanita flowers. The cerioidine was probably using such a pre-existing hole to also access nectar (at the interior base of the flower), after the nectaries had "recharged".

Postscript: Maybe it wasn't bumble or carpenter bees that initially bit the holes in the corollas...just found this paper from studies in the Santa Catalina Mnts and no mention is made of Bombus, Ceratina or Xylocopa nectar-robbing. The supplemental appendix (here) indicates B. melanopygus was observed as a legitimate pollinator on 14 visits, and that various halictids were the primary nectar robbers (i.e. the "hole biters")...while there were lots of hymenoptera, diptera, and lepidoptera recorded visiting as secondary robbers (i.e. visiting after the initial hole was bit open).

Moved from Flies.