These tiny Efferia (I presume) were hanging out in a sandy area on a trail. Size estimated--somewhere around 11-15 mm, I would say. They were much smaller than species familiar to me, such as Triorla interrupta. Here one can see the following mark for Efferia apicalis (see guide page):
-mystax (mustache) with black bristles above and pale yellow hairs below

In close proximity to this female--presumably the same species: