Euphilotes enoptes tildeni

Tilden's Dotted Blue

The Euphilotes blues are a difficult group. My (simplified) understanding of Euphilotes enoptes tildeni is that this is a mid-summer blue using Eriogonum nudum from roughly the San Gabriels to the Tehachapis and the Mt. Piños/Frazier Park area. It is also found north from San Luis Obispo Co. to parts of San Benito, Monterey, and Stanislaus Counties (with Del Puerto Canyon in the latter county the type locality). It was described by Robert Langston in 1963 as Philotes enoptes tildeni, discussed by the Emmels in Butterflies of Southern California in 1973, and then treated as a Euphilotes blue in the major revision by Gordon Pratt and John Emmel in the 1998 Systematics of Western North American Butterflies book. (Pratt had studied Euphilotes blues for his Ph.D. thesis in the 1980s.) An American Butterflies article from 2008 (vol. 16, no. 3), also by Pratt and Emmel, is worth reading; they list five species of buckwheats used by this butterfly throughout its range. But in our area, this blue seems to be well adapted to the timing of its main host, E. nudum, which results in a July-August flight.