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Journal of the Lepidopterists' Society 32(1), 1978, 61-62

ERYNNIS BRIZO LACUSTRA AND HESPERIA COLUMBIA IN THE SIERRA NEVADA

Burns (1964, U. C. Publ. Entomol. 37: 1-214) reports no records for Erynnis brizo lacustra Wright for the Sierra Nevada, and MacNeill (1964, U. C. Publ. Entomol. 35: 1-221) lists no records for Hesperia Columbia Scudder from there except one female in the AMNH from "Sier. Nev." Both are indicator species of the coast range serpentine belts north of San Francisco. Until recently, serpentine outcrops have been little collected in the western foothills of the Sierra Nevada of east-central California. Table 1 (next page) lists the new distribution records there.

Sometimes the adults may fly a few miles from their serpentine areas to hilltop: e.g., both hilltop on Rocky Ridge, 1700-1900', N. of Monticello Dam, Yolo Co., a non-serpentine area composed of Upper Cretaceous marine rocks of the Venado Formation. The nearest serpentine occurs in the extensive Mesozoic ultrabasic intrusive rocks and the Franciscan Formation some 6 miles to the west. Similarly, Footman Ridge, Mariposa Co., is Paleozoic marine (also the area to the N & E), and to the south is Mesozoic granitic rocks, with no serpentine nearby. The nearest serpentine is found 5 mi. W. as Jurassic-Triassic metavolcanic rocks and 8 mi. SW near Mariposa as Mesozoic ultrabasic intrusive rocks. In the meadows, forests, and canyon immediately adjacent to Footman Ridge on the W & N, neither species has ever been collected.

On 15 May 1970, E. slope Walker Ridge along Brim Grade, c. 1800', SW of Leesville, Colusa-Lake Co. line, I noticed a female lacustra ovipositing on the terminal growth of a Quercus durata Jepson bush growing on serpentine soil along a roadbank, at 1125. Burns (1964) says "the skipper invariably occurs in direct association with Q. durata, a serpentine obligate" (see Whittaker et al., 1954, Ecology 35: 258-288). However, in some areas, it may also use Quercus dumosa Nutt. which hybridizes with Q. durata and grows in strictly non-serpentine soils (see Forde & Faris, 1962, Evolution 16: 338-347).

Heretofore, these skippers were considered more coastal in their California distribution.

Oakley Shields, Department of Entomology, University of California, Davis, California 95616.

Table 1. Distribution Records of Erynnis brizo lacustra and Hesperia Columbia fr

b. lacustra Placer

summit of limestone outcrop above Murderer's Bar, V/z mi. E. of confluence of No. & Middle FK. American River, E. of Auburn

C.800' 19 March 1977