Colias harfordiSan Clemente, Orange County, CA. 6-9-13. © Robert Gorman
Similar Species: Very similar to the Alfalfa Caterpillar Butterfly, Colias eurytheme. Harford's Sulfur is distinguished from eurytheme by the lemon yellow background (no orange tint) on the dorsal wing.
Distribution: Colias harfordii has been found in Orange County only in the Santa Ana Mountains, It is infrequently captured, occuring primarily in the larger canyons .
Larval Foodplants: Emmel and Emmel (1973) list these as Astragalus douglasii and A. douglasii var. parishii (locoweeds). There is one record of oviposition on Lotus scoparius. A. douglasii is not known to occur in Orange County, although we do have other Astragalus species - A. brauntonii (locally frequent; old burns; mountains), A. didymocarpus (locally frequent; open places in chaparral) and A. leucopsis (locally frequent; chaparral, coastal plains - -see Boughey, 1968). Harford's Sulfur may utilize one or more of these species as larval foodplants in Orange County, but this needs to be confirmed through observation.
Other Remarks: Evidently Harford's Sulfur has never been a common butterfly in Orange County. None of the longtime Orange County collectors recall ever collecting it locally, although it was almost certainly always present in small numbers in the Santa Ana Mountains.
From Orsak, L. J. (1977). The Butterflies of Orange County, California. Center for Pathobiology Miscellaneous Publication #3. University of California Press, New York. 349pp.