LEPIDOPTERA: HESPERIIDAE
Pyrgus ruralis lagunae Scott, 1981
Date of listing: January, 1997
Federal Status: Endangered
State Status: None
The Laguna Mountains skipper is a small (~3 cm wingspan) member of the skipper butterfly family, the Hesperiidae. The Laguna Mountains skipper is one of two subspecies of Pyrgus ruralis, and is only known from higher elevation areas of southern California. The other is much more widespread, occurring over much of the western U.S., and is generally darker in color.
The larvae of Laguna Mountains skippers feed solely on Horkelia clevelandii, a plant in the rose family. There appear to two flight seasons each year during which the adults mate, one in mid spring and a second in late summer. The adults also rely heavily on the larval host plant as a nectar source.
The Laguna Mountains skipper is known from two areas in San Diego County, Mt. Palomar, as well as the Laguna Mountains for which the butterfly is named. The Mt. Palomar populations appear to be stronger at present. No individuals were seen in the Lagunas in 1994 surveys, though in 1995 a few were observed. That population is currently estimated to contain fewer than 100 individuals. Mt. Palomar is thought to support 4 separate populations, the largest of which comprises approximately 250 individuals. The main factor bringing about the Laguna Mountains skipper’s decline may be the decreasing abundance of their host plant, Horkelia clevelandii. This plant is restricted to montane meadows, which have been degraded through development, grazing, and recreational activities and may itself be threatened. Most of the areas where the Laguna Mountains skipper persists are subject to some grazing. Horkelia clevelandii appears to be a treat for cattle and it is frequently stunted in grazed areas. None of the areas where this butterfly occurs are presently being managed for its survival. The sole remaining Laguna Mountains population occurs in a campground abutting a pasture. Its future is not bright unless it becomes a main focus of management strategies. It would be unfortunate, indeed, if the Laguna Mountains skipper were to disappear from the Laguna Mountains altogether.