Hosmer Lake is getting warm in the lower lake and channel so use your thermometer and do not fish in water temps that will be lethal for catch and release. The Upper channel and upper lake are good with cold spring waters protecting the fish. 
Callibaetis hatches have been good, and there are a lot of damsels so you want nymphs and dries for all of these important hatches. Leeches, Chironomids, small Scuds, Black Caddis, Goddard Caddis, Chubby (makes a fantastic indicator), Ants and Beetles and if you are on the water very early or very late a tiny white mayfly called a Caenis.