Apodemia dialeuca pratti is a spring-flying member of the Mormon Metalmark complex. Note the enlarged white markings. It was described by John and Tom Emmel in the 1998 Systematics book (page 795-6). The host is Eriogonum kennedyi, and these photographs were taken at the type locality, which is Holcomb Valley north of Big Bear Lake. May 23rd, 2009.
The males of Apodemia dialeuca pratti are a bit smaller than the females; this and the one below appeared to be males.
Pratt's Metalmark. The location, Holcolm Valley, is over 7000' in elevation and is an open, flat area surrounded by pine forest. The valley was very active during the California gold rush, and these butterflies were in an area that is one stop on a signed tour of the area's historical landmarks.
Pratt's Metalmark, the ventral side. "Pratt" is Gordon Pratt, a well-known lepidopterist who teaches at UC Riverside.
This female Apodemia dialeuca pratti was ovipositing in the buckwheat. The adults fly early May to mid-June, and the last larval instar overwinters.