She is grasping something on a stamen. The long spines, actually seen better in another view from the same time, distinguish her from a Winter Ant (Prenolepis imparis). Jasper Ridge Biological Preserve, Trail 12 from Mapache Gate, not far from Trail 10, May 13, 2011, 9:36 am. This image is on the cover of my book "Jasper Ridge Ants" (February 2013).