California Sagebrush Gall Midge (Rhopalomyia floccosa) on California Sagebrush (Artemesia californica)
Bill Korbholz writes: "I asked Kathryn Strachota, my go-to source for info about galls, about that fuzzy white gall that we saw on the sagebrush. She id'd it as California sagebrush gall midge, Rhopalomyia floccosa (the specific epithet meaning woolly or flocked, like a Christmas tree). It's very common, especially so this year." Trail 8, 10:20 am.