California Tortoiseshell Butterfly
Reared from caterpillars collected on Ceanothus at Idyllwild, Riverside County, CA. 6/4/11. © Peter J. Bryant
Characteristics: Medium-sized butterfly, rusty orange on DW with dark borders and slightly scalloped wings. Forewing length: 24 - 28 mm.
Habitats, Behavior: California Tortoiseshell adults can be fast fliers and difficult to capture.
Distribution: Spotty records are from the foothills and mountains of Orange County.
Flight Period: Overwintering adults fly from April to June. The progeny from these adults fly from July to August (Emmel and Emmel, 1973). Our records no doubt represent overwintering adults.
Larval Foodplants: California lilac (Ceanothus spp. ). Several species are of common occurrence in the coastal foothills and Santa Ana Mountains of Orange County.
Other Remarks: Theodore Hower mentions that the California Tortoiseshell was exceptionally common throughout the county sometime in the early 1940's, perhaps in 1941, and in connection with a large migration of the Painted Lady (Cynthia cardui). This was also witnessed in March of 1973 during a huge Painted Lady flight through the Santa Ana Mountains. About one out of every 15 migrating butterflies captured turned out to be a California Tortoiseshell. Although californica may occasionally breed locally, the few records do not indicate it to be permanently established.
From Orsak, L. J. (1977). The Butterflies of Orange County, California. Center for Pathobiology Miscellaneous Publication #3. University of California Press, New York. 349pp.