Ceanothus and California Tortoiseshell

The California Tortoiseshell lays its eggs on Ceanothus. But only special kinds of Ceanothus. It likes the varieties with large leaves, like the one pictured here. I guess the smaller leaves don't offer enough foliage to eat. 

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The California Tortoiseshell has an interesting migration pattern. It likes to lay eggs on blooming Ceanothus. So, I see the adults in Berkeley in about March. But by the time the next generation emerges as adults, the ceanothus in Berkeley is generally done blooming, so the butterflies migrate east or north, looking for fresh blooms. The generations continue to higher elevations and higher latitudes, but return to Berkeley for the Ceanothus that blooms in the subsequent March.

Ceanothus is also the host plant for the Ceanothus Silk Moth, a large and beautiful moth. Although it is called the Ceanothus Silk Moth, it lays its eggs on a wide range of plants, including willow, ribes, and manzanita. It is largely a west coast species, ranging from Baja Mexico to California, Oregon, Washington, and into Canada. The adults do not feeds. I guess they put all their energy into reproduction.